analysis of alternatives non-confidential version
TRANSCRIPT
ANALYSIS OF ALTERNATIVES
NON-CONFIDENTIAL VERSION
Legal name of applicant(s): H&R Ölwerke Schindler GmbH
H&R Chemisch Pharmazeutische Spezialitäten GmbH
(co-applicant)
Submitted by: H&R Ölwerke Schindler GmbH
Substance: Sodium dichromate
CAS No. 10588-01-9 (anhydrous)
CAS No. 7789-12-0 (dihydrate)
EC No. 234-190-3
Use title: Use of sodium dichromate as corrosion inhibitor in
ammonia absorption deep cooling systems, applied for
the dewaxing and deoiling process steps of petroleum
raffinate.
Use number: 1
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
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CONTENTS
LIST OF TABLES ........................................................................................................................................................ 4
LIST OF FIGURES ...................................................................................................................................................... 4
LIST OF ABBREVIATIONS ....................................................................................................................................... 5
GLOSSARY ................................................................................................................................................................. 6
DECLARATION .......................................................................................................................................................... 7
IMPORTANT POINTS ON THE IDENTITIES OF KEY STAKEHOLDERS ........................................................... 8
1. SUMMARY ............................................................................................................................................................ 9
2. INTRODUCTION .................................................................................................................................................. 13
2.1 Substance ........................................................................................................................................................ 13 2.1.1 Chemical and physicochemical properties .......................................................................................... 13 2.1.2 Toxicological characteristics ............................................................................................................... 14
2.2 Purpose and benefits of sodium dichromate as corrosion inhibitor ................................................................ 15
3. ANALYSIS OF SUBSTANCE FUNCTION.......................................................................................................... 16
3.1 The role of the AADC systems in the production of base oil and waxes........................................................ 16 3.1.1 Overview of the process ...................................................................................................................... 16 3.1.2 Dewaxing and deoiling ........................................................................................................................ 18
3.2 Industrial AADC systems ............................................................................................................................... 19 3.2.1 Properties and general parameters ....................................................................................................... 19 3.2.2 H&R’s AADC systems in Hamburg and Salzbergen (Germany) ........................................................ 21
3.3 Corrosion and corrosion inhibition in AADC systems ................................................................................... 24 3.3.1 General remarks on corrosion ............................................................................................................. 24 3.3.2 Consequences of the absence of corrosion inhibitors .......................................................................... 25 3.3.3 Corrosion inhibition with sodium dichromate ..................................................................................... 25
4. ANNUAL TONNAGE............................................................................................................................................ 29
5. IDENTIFICATION AND IMPLEMENTATION OF POSSIBLE ALTERNATIVES .......................................... 30
5.1 Description of efforts made to identify possible alternatives .......................................................................... 30 5.1.1 Research and development activities ................................................................................................... 30 5.1.2 Consultations and directed communications ....................................................................................... 30
5.2 Overview on the process of alternative development and industrial implementation..................................... 32
5.3 List of possible alternatives ............................................................................................................................ 35
6. SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR THE AADC SYSTEMS OF
H&R ............................................................................................................................................................................. 36
6.1 Alternative 1: Replacement (change) of the cooling system .......................................................................... 36
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
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6.1.1 Properties/Description ......................................................................................................................... 36 6.1.2 Technical feasibility ............................................................................................................................ 36 6.1.3 Economic feasibility ............................................................................................................................ 37 6.1.4 Reduction of overall risk due to transition to the alternative ............................................................... 38 6.1.5 Availability .......................................................................................................................................... 39 6.1.6 Conclusion on suitability and availability ........................................................................................... 39
6.2 Alternative 2: Replacement of corrosion prone parts ..................................................................................... 39 6.2.1 Properties/Description ......................................................................................................................... 39 6.2.2 Technical feasibility ............................................................................................................................ 39 6.2.3 Economic feasibility ............................................................................................................................ 40 6.2.4 Reduction of overall risk ..................................................................................................................... 42 6.2.5 Availability .......................................................................................................................................... 42 6.2.6 Conclusion ........................................................................................................................................... 42
6.3 Alternative 3: Substitution of sodium dichromate as corrosion inhibitor ....................................................... 42 6.3.1 Technical requirements for corrosion inhibitors at the applicants sites ............................................... 43 6.3.2 Assessment of alternative corrosion protective substances: Category 1 .............................................. 44 6.3.2.1 Molybdate compounds ........................................................................................................................ 44 6.3.2.2 Sodium nitrite ...................................................................................................................................... 46 6.3.2.3 Silicates/water glass ............................................................................................................................ 49 6.3.2.4 Zinc containing corrosion inhibitors.................................................................................................... 51 6.3.2.5 Strong alkaline solutions ..................................................................................................................... 54 6.3.2.6 Phosphates and phosphonate compounds ............................................................................................ 56 6.3.2.7 Rare Earth Metal Salts ......................................................................................................................... 59
7. OVERALL CONCLUSION ON SUITABILITY AND AVAILABILITY OF CORROSION INHIBITOR
ALTERNATIVES ........................................................................................................................................................ 61
8. REFERENCES........................................................................................................................................................ 63
APPENDICES .............................................................................................................................................................. 67
Appendix 1 - Category 2 alternatives ...................................................................................................................... 67
Appendix 2 – Information on chemical substances assessed in Section 6.3 ........................................................... 74
ANALYSIS OF ALTERNATIVES
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LIST OF TABLES
Table 1: Summary of alternative evaluation. Red area: the parameters/assessment criteria do not fulfil the requirements
Yellow area: the parameters/assessment criteria fulfilment is not yet clear Green area: the parameters/assessment
criteria do fulfil the requirements White area: no data available .................................................................................. 11 Table 2: Substance subject to this AoA. ...................................................................................................................... 13 Table 3: Physical and chemical characteristics of sodium dichromate ........................................................................ 14 Table 4: Harmonized classification of sodium dichromate .......................................................................................... 14 Table 5: Example products made from base oil, slack wax, foots oil and paraffin ...................................................... 16 Table 6: Important parameters and functionalities of sodium dichromate as corrosion inhibitor ................................ 26 Table 7: Categorized list of alternative corrosion inhibitors ........................................................................................ 35 Table 8: Advantages of the two cooling technologies ................................................................................................. 37 Table 9: Net Economic Impacts – replacement (change) of the cooling system ......................................................... 38 Table 10: Net Economic Impacts – replacement of corrosion prone parts .................................................................. 41
LIST OF FIGURES
Figure 1: Expected timeframe of sodium dichromate substitution in the AADC systems in Hamburg and Salzbergen
(Germany) ..................................................................................................................................................................... 12 Figure 2: Broad overview of operations of the applicants: Base oil and wax production. ATM = Atmospheric Residue,
VGO = Vacuum Gas Oil, DAO= De-Asphalted Oil ..................................................................................................... 17 Figure 3: Generic overview of operations in Salzbergen (above) and Hamburg (below). While the operations in
Salzbergen comprise de-waxing with integrated deoiling, the operations in Hamburg comprise dewaxing only. ....... 17 Figure 4: Photographs of feedstock and products: Dewaxing: feedstock (raffinate, left), base oil product (middle), and
slack wax (right) ........................................................................................................................................................... 18 Figure 5: Photographs of feedstock and products: Combined Dewaxing and Deoiling: feedstock (raffinate, far left),
base oil product (second left), hard paraffin wax (second right), foots oil (far right) ................................................... 19 Figure 6: Simplified functional scheme of an AADC system ..................................................................................... 20 Figure 7: H&R’s AADC system in Salzbergen (Germany). ........................................................................................ 23 Figure 8: Expected timeframe of sodium dichromate substitution in the AADC systems in Hamburg and Salzbergen
(Germany) ..................................................................................................................................................................... 34
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
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LIST OF ABBREVIATIONS
AADC Ammonia Absorption Deep Cooling
AfA Application for Authorisation
AoA Analysis of Alternatives
AC Alternating Current
bar(a) Unit for absolute pressure
Cr(VI) Hexavalent Chromium
CSR Chemical Safety Report
DMEA N,N′-Dimethylethanolamine
EC European Commission
ECHA European Chemicals Agency
EPO European Patent Office
EU European Union
H2 Hydrogen
HPA Hydroxy Phosphonic Acid
IE (Corrosion) Inhibition Efficiency
MSG Mono Sodium Glutamate
MTI Materials Technology Institute
MW Megawatt
N2 Nitrogen
Na2Cr2O7 Sodium dichromate
NPV Net Present Value
NUS Non Use Scenario
O2 Oxygen
R&D Research and Development
RAC Committee of Risk Assessment
REACH Registration, Evaluation, Authorisation and Restriction of Chemicals
SEA Socio-Economic Analysis
SVHC Substance of Very High Concern
TSP Trisodium Phosphate
US United States
VCC Vapour Compression Cooling
W Watt
ANALYSIS OF ALTERNATIVES
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GLOSSARY
Term Definition
Category 1 alternative
Initial R&D efforts on ammonia water based absorption systems
can be found. Although partly tested on test vessels or
commercially available small scale units, they are far away from
being applied on the industrial scale. Respective R&D is mostly
of basic nature than ongoing.
Category 2 alternative
Only indications for the use as corrosion inhibitor for carbon
steel was found in the course of the literature review. Results are
restricted to the laboratory scale and no indication for the use in
ammonia water based absorption systems is present. In addition,
Category 2 alternatives exhibit technical limitations leading to
dismissal.
Corrosion protection Means applied to the metal surface to prevent or interrupt
oxidation of the metal part leading to loss of material.
Industrial scale Large cooling systems with capacities of >2 MW for industrial
applications such as chemical synthesis, refineries etc.
Risk reduction
Classification and labelling information of substances and
products reported during the consultation being used for
alternatives / alternative processes are compared to the hazard
profile of the used sodium dichromate
Rich solution Aqueous ammonia solution with high ammonia content (approx.
26 %).
Small scale
Commercially available ammonia water (cooling) systems for
household applications such as refrigerator, medical boxes, air
conditioning etc. with capacities of several hundred Watts.
Test vessel
Test system typically made of carbon steel that can be brought to
similar temperature and pressure as at the critical points of an
absorption cycle.
Most of the effectiveness tests on alternative corrosion inhibitors
are performed in vessels measuring the amount of corrosion
gases and finally analyses the sample surface. Simulation vessels
are used for cost reasons, so that an entire machine incorporating
an absorption cycle does not have to be used, often for thousands
of hours, at each test on a new corrosion inhibitor.
Poor solution Aqueous ammonia solution with low ammonia content (approx.
11-12 %)
ANALYSIS OF ALTERNATIVES
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IMPORTANT POINTS ON THE IDENTITIES OF KEY STAKEHOLDERS
H&R GmbH & Co. KGaA: H&R GmbH & Co. KGaA (H&R KGaA) is a holding company
which owns (partially or wholly) several subsidiaries based around the globe which would be
affected by a refused authorisation. Among those, those more important to this analysis are the
two companies who own the two refineries that use sodium dichromate (see below).
The two refineries: At the core of H&R KGaA are two refineries, both located in Germany, one
in Hamburg and another one in Salzbergen. The Hamburg refinery is owned and operated by
H&R Ölwerke Schindler GmbH (H&R OWS), while the Salzbergen refinery is owned and
operated by H&R Chemisch Pharmazeutische Spezialitäten GmbH (H&R CPS). These two
companies are the applicants for this joint Application for Authorisation and are collectively
referred to as such throughout this document.
Hansen & Rosenthal Group: The Hansen & Rosenthal Group owns xxx of H&R KGaA and
acts as selling partner directly linked to the two refineries. Four such companies are offering
marketing and sales services, all based in Germany:
Hansen & Rosenthal KG
Klaus Dahleke KG
Tudapetrol Nils Hansen Mineralölerzeugnisse KG
H&R Wax & Specialties GmbH
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
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1. SUMMARY
Use of sodium dichromate by the applicants:
This Analysis of Alternatives (AoA) forms part of the Application for Authorisation (AfA) to
continue the use sodium dichromate as corrosion inhibitor in Ammonia Absorption Deep Cooling
(AADC) systems operated by the applicants H&R Ölwerke Schindler GmbH in their refinery in
Hamburg and H&R Chemisch Pharmazeutische Spezialitäten GmbH in their refinery in Salzbergen
(Germany). Both legal entities are part of H&R GmbH Co. KGaA and act as joint applicants.
The applicants use the AADC systems to generate cold, which is required for the process steps of
dewaxing and deoiling of raffinates to obtain base oil and waxes. Base oil and waxes serve as raw
materials for the production of various products such as lubricants, motor oil, candles, inks, electrical
insulation or composite wood panels. Sodium dichromate is used in the working fluid (ammonia water
mixture) of the AADC systems as an additive to inhibit corrosion of the carbon steel which the
systems are made of.
The annual tonnage is xxxxxxx (≤ 0.01 tonnes) sodium dichromate [xxxxx as Cr(VI)].
Important substance properties:
The following key functionalities are considered essential for the use of sodium dichromate as
corrosion inhibitor in AADC systems:
Corrosion protection for carbon steel in ammonia/water based systems by formation of a
passivation layer in the absence of oxygen;
Prevention of formation of non-condensable (inert) gases;
Active corrosion inhibition when a coating is damaged;
Inhibitor does not negatively influence the ammonia absorption refrigeration process;
Non-volatile corrosion inhibitor with proven long-term stability.
The AADC systems, which are designed as closed systems, operate at a broad temperature range (35
- 165 °C), different pressures, alkaline pH (9 - 12), high fluid velocities and under very low oxygen
levels. As of today, Cr(VI) based substances are the only proven corrosion inhibitors suitable for the
use under such conditions.
Alternative assessment:
Three different alternative options are discussed in this AoA:
Replacement (change) of the cooling system with a system making use of a different cooling
technology, e.g. Vapour Compression Cooling (VCC) (Section 6.1)
Replacement of corrosion prone parts with parts made of more resistant materials, e.g.
stainless steel (Section 6.2)
Substitution of sodium dichromate as corrosion inhibitor in existing AADC systems
(Section 6.3)
ANALYSIS OF ALTERNATIVES
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As a first option, the exchange of the existing AADC systems to an alternative cooling technology,
namely VCC, is described in Section 6.1. VCC systems are described to be operated without corrosion
inhibitor due to the absence of water and oxygen in completely closed systems. Even though
technically feasible, a switch to VCC would in H&R’s case amount to net economic impacts of
EUR 40 million (considering investment in a new cooling system, value added forgone due to
downtime and additional operational costs), which is why replacing the AADC systems with VCC
systems is not considered feasible from an economic standpoint.
As described in Section 6.2, the replacement of corrosion prone parts, mainly carbon steel parts by
more resistant parts, e.g. stainless steel or permanently coated metal parts, was also assessed for
suitability as alternative. As of today, no standard or best-practice solution is applicable for AADC
systems. It was highlighted that stainless steel systems of this size are currently not operated and no
reliable conclusion about the presence or absence of corrosion inhibitors in such systems can be
drawn. It was also clearly outlined that stainless steel is subject to corrosion in ammonia/water
systems, especially at higher temperatures. At present, no information exists on corrosion inhibition
for systems made of stainless steel. It is still questionable whether AADC systems in such dimensions
could be safely operated over the timeframe of decades without any corrosion inhibitor, despite the
use of stainless steel parts. It was also recommended by specialists that in this case only sodium
dichromate is proven for use as a long-term corrosion inhibitor. Therefore, from a technical
perspective, the exchange of corrosion prone parts cannot be considered as a suitable alternative.
In Section 6.3 the substitution of sodium dichromate by another corrosion inhibitor is described in
detail. Extensive efforts were made during the last years to identify possible alternatives for corrosion
inhibitors in AADC systems. In course of these efforts, scientific literature was screened and
evaluated comprehensively. Experts from other companies dealing with similar cooling systems were
approached. Moreover, several other international research institutes were contacted to discuss and
evaluate the state of the art for corrosion inhibition in these types of cooling systems. In summary,
this analysis revealed that there is limited experience available on replacement substances for large
scale industrial AADC systems. Despite all efforts, the current state of knowledge shows that a
technically feasible drop-in alternative to sodium dichromate for the use as corrosion inhibitor is not
available, neither for large scale industrial AADC systems nor for small scale applications. An
overview on the performance of the alternatives can be found in Table 1.
ANALYSIS OF ALTERNATIVES
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Table 1: Summary of alternative evaluation.
Red area: the parameters/assessment criteria do not fulfil the requirements.
Yellow area: the parameters/assessment criteria fulfilment is not yet clear.
Green area: the parameters/assessment criteria fulfil the requirements.
White area: no data available.
Expected time-scale of sodium dichromate substitution:
AADC systems made of carbon steel constitute a safe and reliable cooling technology. Using sodium
dichromate as corrosion inhibitor ensures a long-lasting life time of the cooling plants: up to 50 years.
Most alternatives discussed in scientific and technical literature were not tested under realistic
conditions in large-scaled systems for a realistic time span. For the development and industrial
upscaling of a possible alternative for sodium dichromate as a corrosion inhibitor for AADC systems
made of carbon steel, several phases are necessary. The integrity and reliability of the system must
be ensured over the expected lifetime of the facility. Unexpected corrosion would lead to system
downtime associated by immense costs and reduced environmental and occupational safety. In this
context, it would be unjustifiable to simply start a substitution in form of a field trial without having
enough scientific and empirical data about the safe use of such alternatives.
In Section 5.2 the expected timeline of a possible sodium chromate substitution process is described.
The substitution process can be divided into three phases: Research and Development (R&D), up-
scaling and implementation. The development process must start with a search for alternatives, which
has already been initiated with the development of this AfA. A literature-based analysis of possible
corrosion inhibitors and communications with experts was performed for the purpose of the AfA by
Arlanxeo Netherlands B.V., for which the applicants hold a letter of access.
The challenging issue in this context is evident in the fact that H&R is the operator but not the
manufacturer of the AADC systems, and the downstream user of sodium dichromate as a corrosion
inhibitor. H&R is aware of their responsibility as operator of AADC systems to contribute to the
investigation of all potential alternatives.
Alternative
Experience
at industrial
scale
Experience
at small
scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
35-165 °C
Effective at
alkaline pH
(9-12)
Effective in
absence of
oxygen
Molybdate
Sodium
nitrite
Silica/ water
glass
Silicates/
water glass
only
Silicates/
water glass
only
Silicates/
water glass
only
Zinc
compounds
Strong
alkaline
solutions
Phosphates
Rare earth
metal salts
ANALYSIS OF ALTERNATIVES
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Continuous monitoring of the robustness and reliability of the alternative is important to avoid any
failure of the replacement potentially causing severe consequences. In this context it is also of the
utmost importance to have the possibility to keep the system running in case the (technical or
chemical) alternative fails. For this purpose, the option to switch back to the use of sodium
dichromate must be available until a reliable solution is found.
As clearly outlined, passing Phase I and II will take up to 15 years. Assuming that initiatives will start
in 2017, it is anticipated that the process can easily take until 2032. The next maintenance window
for the connected production plant, which is accompanied by a temporary production stop, will also
take place in 2032 (five-year rhythm with the latest window in 2017). At least another five years are
required for performance monitoring, adding up the overall required time of 20 years. Besides this, it
must be considered that the remaining life time of the AADC systems operated by H&R is at least 35
years (Hamburg) and at least 20 years (Salzbergen). Therefore, these AADC systems are estimated
to be in use until 2037 and 2052 respectively (see Figure 1).
Figure 1: Expected timeframe of sodium dichromate substitution in the AADC systems in Hamburg and
Salzbergen (Germany)
All in all, passing the complete development and implementation process plus the required
monitoring will easily take 20 years. Taking into account the limited worker exposure to sodium
dichromate in combination with extremely high occupational safety measures (see CSR), the resulting
considerable low health impacts (under existing conditions there is no concern and negligible risk for
workers and the environment) and the comparably high economic impacts (see SEA), the most
reasonable option is to run the AADC systems operated by H&R until the end of their expected
lifetime (20 to 35 years from now). Therefore, H&R applies for a review period of 20 years for the
use of sodium dichromate.
ANALYSIS OF ALTERNATIVES
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2. INTRODUCTION
The present document constitutes the Analysis of Alternatives (AoA) as part of the Application for
Authorisation (AfA) to continue the use of sodium dichromate as corrosion inhibitor in Ammonia
Absorption Deep Cooling (AADC) systems operated by H&R Ölwerke Schindler GmbH in their
refinery in Hamburg and H&R Chemisch Pharmazeutische Spezialitäten GmbH in their refinery in
Salzbergen (Germany). In both cases the AADC system is critical for the dewaxing and deoiling of
raffinate to obtain base oil and waxes. Both legal entities are part of H&R GmbH Co. KGaA and act
as joint applicants. H&R Ölwerke Schindler GmbH and H&R Chemisch Pharmazeutische
Spezialitäten GmbH will be referred to in short as “H&R”.
The following Section 2.1 gives an overview of sodium dichromate and respective chemical and
physicochemical properties as well as toxicological characteristics. The purpose and benefits of using
sodium dichromate as corrosion inhibitor are introduced in Section 2.2.
H&R holds a Letter of Access (LoA) for the AfA Arlanxeo Netherlands B.V. filed in 2015 for the
use of sodium dichromate as corrosion inhibitor in ammonia absorption deep cooling systems. The
AfA was originally filed by Lanxess Elastomers B.V. before a legal entity change. It will be referred
to in short as “the Arlanxeo AfA”. Therefore the present AoA includes both, information from the
Arlanxeo AoA and information from H&R.
2.1 Substance
The following substance, as described in Table 2 is subject to this AoA.
Table 2: Substance subject to this AoA.
Substance Latest application date1 Sunset date2
Sodium dichromate (Na2Cr2O7)
CAS No. 10588-01-9 (anhydrous)
CAS No. 7789-12-0 (dihydrate)
EC No. 234-190-3
21 March 2016 21 September 2017
1 Date referred to in Article 58(1)(c)(ii) of Regulation (EC) No. 1907/2006 2 Date referred to in Article 58(1)(c)(i) of Regulation (EC) No. 1907/2006
Sodium dichromate is an inorganic hexavalent chromium [Cr(VI)] salt, which has been identified as
Substance of Very High Concern (SVHC) and which has been included into Annex XIV to Regulation
(EC) No 1907/2006 ('REACH') due to its intrinsic properties as being carcinogenic (Carc. 1B),
mutagenic (Muta. 1B) and toxic to reproduction (Repr. 1B).
2.1.1 Chemical and physicochemical properties
Sodium dichromate is an odourless essentially non-volatile solid and appears as bright red-orange
crystal needles. Sodium dichromate is hygroscopic and very soluble in water and often found as
dihydrate. The aqueous solution of sodium dichromate is acidic and a strong oxidising agent. Physical
and chemical characteristics of sodium dichromate are summarized in Table 3.
ANALYSIS OF ALTERNATIVES
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Table 3: Physical and chemical characteristics of sodium dichromate
Parameter Value
CAS No. 10588-01-9 (anhydrous)
7789-12-0 (dihydrate)
EC No. 234-190-3
Chemical formula Na2Cr2O7
Molecular weight 261.97 g/mol
Water solubility at 20°C ca. 2.355 g/L
Specific gravity 2.52 g/cm³
pH value at 25 °C and for a solution of
100 g/L 3.5
Melting point 356.7 °C
Boiling point (decomposition) > 400 °C
Physical state Odourless orange to red crystals or granules
Stability Stable under ordinary conditions
2.1.2 Toxicological characteristics
Cr(VI) compounds like sodium dichromate are known to induce multiple acute and chronic health
effects. Sodium dichromate is harmonized classified under Annex VI to Regulation (EC) No
1272/2008 (CLP Regulation), which is summarized in Table 4.
Table 4: Harmonized classification of sodium dichromate
Hazard Class and Category
Code(s)
Hazard Statement
Code(s) Pictograms
Ox. Sol. 2 H272
Acute Tox. 3 H301
Acute Tox. 4 H312
Skin Corr. 1B H314
Skin Sens. 1 H317
Acute Tox. 2 H330
Resp. Sens. 1 H334
Muta. 1B H340
Carc. 1B H350
Repr. 1B H360FD
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Hazard Class and Category
Code(s)
Hazard Statement
Code(s) Pictograms
STOT RE 1 H372
Aquatic Acute 1 H400
Aquatic Chronic 1 H410
2.2 Purpose and benefits of sodium dichromate as corrosion inhibitor
Cr(VI) substances offer a broad range of functions which have been widely utilized for over 50 years
in the industry for various applications. The multi-functionality of Cr(VI) compounds provides major
properties within the respective processes. The following key functionalities are essential for the use
of sodium dichromate as corrosion inhibitor in AADC systems as they are subject of this AoA:
- Excellent corrosion protection and prevention for nearly all metals in a wide range of
environments;
- Proven technology for AADC systems – for application at high temperature in the desorber,
very low oxygen content, water rich material, high velocity;
- Effective at prevalent conditions; i.e. alkaline pH > 9, temperatures between 35–165 °C and
high liquid velocity;
- Prevention of formation of non-condensable (inert) gases;
- Formation of passivation layer in the absence of oxygen;
- Active corrosion inhibition when a coating is damaged, e.g. by a scratch exposing the base
material to the environment, the solubility properties of sodium dichromate enable them to
diffuse to the exposed area and inhibit corrosion;
- Inhibitor does not influence adsorption / desorption process;
- Product stability under the applied process conditions;
- Long-term stability of the corrosion inhibitor;
- No fouling/loose sedimentation products;
- Non-volatile; and
- Inhibits the growth of microorganisms in the cooling system
A detailed description of function of sodium dichromate is given in Chapter 3, including further
elaboration on key functionalities touched upon above in Section 3.3.
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3. ANALYSIS OF SUBSTANCE FUNCTION
In order to be able to assess possible alternatives to sodium dichromate as corrosion inhibitor in
AADC systems, the following section provides background information on the industrial application
sodium dichromate is used in and properties, parameters as well as mechanisms which provide the
desired functioning.
Therefore, in Section 3.1 a general overview of the production process of base oil and waxes and the
special process step that involves the AADC systems is provided.
In Section 3.2 industrial uses of AADC systems, their properties and general parameters (3.2.1), as
well as the specific application at the H&R production sites in Hamburg and Salzbergen (Germany).
(3.2.2) are described.
Corrosion and its inhibition in AADC systems is further elaborated in Section 3.3, including a general
introduction to the issue of corrosion (3.3.1), resulting consequences (3.3.2) as well as the functioning
of sodium dichromate as corrosion inhibitor in AADC systems (3.3.3).
3.1 The role of the AADC systems in the production of base oil and waxes
3.1.1 Overview of the process
H&R produces base oil and waxes (slack wax, foots oil and paraffin) at the refineries in Hamburg
and Salzbergen (Germany). Both refineries process similar raw material (Vacuum Gas Oil,
Atmospheric Residue) with very similar main production steps (distillation, extraction,
dewaxing/deoiling and hydrofinishing). The AADC system is necessary to provide the required low
process temperature in the dewaxing/deoiling process step, from which base oil and waxes are
separated. From these raw materials more than 800 different specialty products are produced (see
Table 5 for examples). An effective dewaxing/deoiling step is essential for achieving product
specifications.
Table 5: Example products made from base oil, slack wax, foots oil and paraffin
Base oil lubricating greases, motor oil, metal processing fluids
Slack wax candles, polishes, matches, inks, carbon paper, canvass coatings, and composite
wood panels
Foots oil petroleum jelly, further refinement with e.g. hydro treatment
Hard paraffin
wax
lubrication, electrical insulation, candles, crayons
The purpose of dewaxing is to separate waxy components from oil products out of the extraction
plants to obtain a base oil with a low pour point. As a “side product” waxes are won, which also serve
as raw material for various applications (see Figure 2).
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Figure 2: Broad overview of operations of the applicants: Base oil and wax production. ATM = Atmospheric
Residue, VGO = Vacuum Gas Oil, DAO= De-Asphalted Oil
The applicants have two dewaxing/deoiling units, which are supplied with cold by AADC systems.
One of these units is located in Salzbergen and is called “EP”. The unit is a 2-filtration-stage process
with a dewaxing stage and integrated deoiling stage (see Figure 3).
The other unit, called “EP2” is located in Hamburg and is used for a 1-filtration-stage process for
dewaxing only (see Figure 3).
The Hamburg and Salzbergen sites have similar processes, technical equipment and risk management
measures for dewaxing and deoiling activities. Therefore, all technical descriptions below are
common for the Hamburg and Salzbergen sites.
The units run continuously, except for scheduled stops as required by legislation, and as described in
the CSR to this application.
Figure 3: Generic overview of operations in Salzbergen (above) and Hamburg (below). While the operations
in Salzbergen comprise de-waxing with integrated deoiling, the operations in Hamburg comprise dewaxing only.
The cooling step is specifically essential for the dewaxing and deoiling process in order to achieve
the separation of the oil fraction from the wax fraction. This process step is discussed in detail in the
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following section. For further information on products, markets, uses and the production process
please refer to the SEA document.
3.1.2 Dewaxing and deoiling
In the dewaxing step, the wax is separated from the base oil. Therefore, the raffinate (the feed) has to
be diluted with a selective solvent and chilled to a low temperature (-20 °C). By lowering the
temperature the waxy components begin to crystallise. The solid waxy crystals can then be removed
by filtration. The product emerging from this process is a base oil. It is ready for sale or further
processing (e.g. hydro-finishing). The other, waxy fraction that is won in the process is called slack
wax. It still contains some oil (typically 3 to 16 %).
In EP (Salzbergen) a second filtration step, the deoiling, is applied to further purify the waxy fraction
and win foots oil (a soft wax) and hard wax (paraffin). In the process step the temperature is increased
to melt the lower wax fractions, which are then separated from the higher wax fraction again by
filtration. However, the deoiling also takes place at low temperatures of 0 to +5 °C. Therefore cooling
is nevertheless important in order to keep the feed wax in a solid state and prevent higher temperatures
in the deoiling step itself.
The basic products of the above processes are shown in Figure 4 and Figure 5.
Figure 4: Photographs of feedstock and products: Dewaxing: feedstock (raffinate, left), base oil product
(middle), and slack wax (right)
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Figure 5: Photographs of feedstock and products: Combined Dewaxing and Deoiling: feedstock
(raffinate, far left), base oil product (second left), hard paraffin wax (second right), foots oil (far right)
3.2 Industrial AADC systems
3.2.1 Properties and general parameters
Cooling systems cooling air, liquids and solids, are widespread for private and industrial applications.
Industrial cooling systems are essential to many types of manufacturing processes. This can include
the removal of excess heat from a process or, as in this specific case, the separation fractions with
different melting/freezing points from one another.
Ammonia absorption refrigeration is widely used in industrial sectors where the total demand of
cooling can be extraordinarily high. Ammonia is an excellent refrigerant for cooling systems which
are either driven by steam, pressurized hot water or directly with the exhaust gases. Main aspects of
AADC systems are:
- Able to reach very low temperatures
- Driven by heat, which results in very low operational costs if the heat is residual heat
- Well partial load performance, whereas efficiency increases at partial load
- High durability of the system due to very few moving components
- Specific safety measures required due to ammonia as refrigerant (depending on the application
area)
- Relatively high investment costs
- Relatively low maintenance costs
AADC systems are able to produce cold down to -60 °C using (excess) heat as the main energy source.
The liquid ammonia evaporates at low (sub-atmospheric) pressure while cooling down the reactor
feed (monomers) in the evaporator. The ammonia absorption refrigeration process/cycle can be
subdivided into the following four basic steps, as to see in Figure 6.
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Figure 6: Simplified functional scheme of an AADC system
Step 1:
In the evaporator (I) liquid ammonia is evaporated at low (subatmospheric) pressure by taking the
required energy ('heat of evaporation') from surrounding area. Upon which the product (in H&R’s
case raffinate), which is pumped through the evaporator in a separate circuit, is cooled down ('chilled
medium').
Step 2:
The ammonia vapour generated in Step 1 is transferred to the absorber (II), where it is taken up
(absorbed) by an aqueous ammonia solution with a low ammonia content ('poor solution') leading to
an ammonia enriched solution ('rich solution'), which is fed to a rectification column that is
connected to the desorber (III).
Step 3:
By heating up in the desorber (III) the 'rich solution' generated in Step 2 is separated into 'poor
solution', consisting mainly of water and 'vapour', consisting mainly of ammonia.
The 'poor solution' is sent back to the absorber to again absorbing ("used") ammonia vapour and
producing a 'rich solution'. Whereas the 'vapour' is purified in the rectification column to result in
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nearly pure ammonia vapour. The vapour stream leaving the rectification column consists of nearly
pure ammonia and is subsequently liquefied in the condenser.
Step 4:
The ammonia vapour generated in Step 3 is liquefied in the condenser (IV) and again fed into the
evaporator.
3.2.2 H&R’s AADC systems in Hamburg and Salzbergen (Germany)
H&R operates two AADC systems. One in the refinery in Hamburg and one in Salzbergen. The
AADC systems produce the cold required for the dewaxing and deoiling process in the production of
base oil and waxes. The feed raffinate has to be cooled down to about -20 °C. For this purpose, the
ammonia needs to be cooled down to about -30 °C.
The cooling capacity is xxxx (-32 °C) for the AADC in Hamburg and xxxxxxxx (-30 °C) for the
AADC in Salzbergen. Both systems are driven with steam of about 11 bar(a), which is generated on-
site with heat from the waste incineration. The content of 'cooling medium' within the system is
approx. xxx for the AADC in Hamburg and approx. xxxx for the AADC in Salzbergen. The two
AADC systems operated by H&R have an expected remaining life time of at least 20 additional years
(Hamburg approx. 35 years, Salzbergen approx. 20 years) assuming current operating conditions and
normal maintenance.
The process parameters for the two AADC systems partly differ from each other. The subsequent
description focuses on the system in Hamburg. In addition the parameters of the system in Salzbergen
are provided in brackets next to the Hamburg values.
Desorber and rectification:
In the desorber, which is supplied with overheated steam of up to 230 °C (Salzbergen 340 °C), boils
a fluid mixture of about 12 % ammonia and 88 % water. Inside the desorber there is a temperature of
165 °C and a pressure of 15 bar(a). The emerging steam phase contains a high content of ammonia
and forms a thermodynamic equilibrium with the liquid phase. The steam is purified of residual water
in the rectification column. The head product of the rectification column finally is almost water-free
high-pressure ammonia steam with a temperature of 50 °C. Parts of the condensate are led back to
the column, for the purpose of better clearing of the ammonia containing steam from the residual
water.
Condensation process:
The ammonia steam is condensed in a water-cooled condenser and collected in a collector.
Afterwards, the condensate is cooled down to 0 °C (Salzbergen +5 °C) in a cold exchanger in order
to improve the cooling capacity in the following expansion.
Evaporation process
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In the expansion valve the subcooled condensate is expanded to evaporating pressure of about 1 bar(a)
and as a fluid-steam-mixture with a temperature of -32 °C (Salzbergen -30 °C) proceeds further to
the evaporator. From the evaporator the liquid ammonia is transported to the different consumers,
where a part of the ammonia is evaporated and thus the required cold is generated. The evaporated
ammonia as well as the residual fluid are pumped back to the evaporator. The steam is led to the cold
exchanger and the liquid ammonia is pumped back to the consumers.
Superheating of the steam
The saturated ammonia steam which is led to the cold exchanger is superheated by the bypassing
condensate to a temperature of up to +25 °C (Salzbergen +30 °C) and lead to subcooling of the
condensate.
Bleed
The condensate that flows to the evaporator contains residual water. This water cannot evaporate in
the evaporator. To prevent accumulation of water in the evaporator, the water (the so called “bleed”)
needs to be removed from the ammonia evaporation cycle to maintain the right ammonia
concentration.
Subcooling of the poor solution
From the desorber the poor solution (11-12 % ammonia, approx. 164 °C (Salzbergen 165 °C)) is led
to a solution-heat exchanger. Where it is subcooled to about 40 °C. In the expansion valve the poor
solution is relaxed to evaporation-pressure (approx. 1 bar(a)) and then led to the absorber.
Absorption process
The NH3-steam generated in the evaporator and the cold exchanger are, just as the poor solution, led
to the absorber. The two currents mix and form the rich solution (approx. 26 % ammonia). The heat
of solution generated in this process is transferred to the cooling water. The rich solution, which has
now a temperature of about 35 °C (Salzbergen 34 °C) is collected.
Heating of the rich solution
The rich solution is transferred to the solution heat exchanger and heated to about 135 °C. It is then
used as feed for the rectification column. A part of the cold poor solution is also led to the rectification
column to improve the heat ratio of the plant.
Finally, the cycle is complete. The process is very complex and highly demanding to the hardware
components due to the extreme temperatures, pressure levels and ammonia concentrations. The
constructions, piping and equipment are made of (cold resistant) carbon steel, which known as a
material that can be used under these conditions. Exemplarily, Figure 7 shows the AADC system in
Salzbergen (see also CSR).
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Figure 7: H&R’s AADC system in Salzbergen (Germany).
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3.3 Corrosion and corrosion inhibition in AADC systems
3.3.1 General remarks on corrosion
Corrosion is the gradual destruction of materials by an electrochemical reaction. The most important
form of corrosion occurs when steel is exposed to an aqueous environment causing the metal to rust.
For the construction of absorption cooling systems using ammonia water mixture as working fluid
('cooling medium') most often carbon steel is used due to its availability, economic advantages and
the easy handling, including forming or welding. The corrosion of carbon steel is an electrochemical
process involving a chemical change of iron to iron oxide and an electrical process involving electron
current flow. In an anaerobic system under the given parameters of an AADC system it is considered
that the following reactions are most common:
(1) Fe + H2O FeO + H2
(2) 2 FeO + H2O Fe2O3 + H2
(3) 3 FeO + H2O Fe3O4 + H2
These processes cause a decomposition of the material. The decomposition of the material influences
the integrity of the whole cooling plant. Additionally, the formation of gaseous hydrogen occurs,
which is a key problem for ammonia based cooling systems. The non-condensable hydrogen
accumulates in the system, primarily in the condenser and absorber units. As a consequence, hydrogen
absorbed in those units drastically hampers the condensation and absorption process of ammonia
refrigerant.
In recirculating water systems, such as cooling or heating systems, the main factors influencing the
corrosion rate are temperature, oxygen concentration, dissolved salts, pH and solution velocity (flow
rate). When the water temperature is increased, the corrosion rate increases. Dissolved oxygen
entering the system in the water may cause severe corrosion. H&R’s Ammonia absorption cooling
systems are operated at temperatures between 35 °C and to 165 °C. Each AADC system is designed
as a closed system. Generally, compared to an open system the potential for oxygen corrosion issues
is reduced, as the recirculating solution is usually not in contact with air (oxygen).
The flow rate is another crucial factor when evaluating the corrosion rate of recirculating water
systems. It has a direct influence on the erosion-corrosion, also known as Flow Accelerated Corrosion
(FAC). This effect can be defined as the acceleration in the rate of corrosion attack on metal,
proportional to the relative motion of a fluid at a metal surface. It typically occurs in structures where
flow direction or velocity is altered (e.g. pipe bends (elbows) or tube constrictions). It is mostly
prevalent in systems using aluminium or copper alloys, as well as carbon steel. Erosion-corrosion can
be characterized as a mechanical removal of the protective oxide layer from a metal surface by a
continuous flow of fluid. Once the metal surface is exposed, increased corrosion rates can be
observed. If the protective metal oxide layer cannot be formed/regenerated quickly enough,
significant damage to the system may occur. Again, it is important to consider the temperature and
pH of the circulating solution. Higher temperatures and, lower local flow rates minimize the risk for
erosion-corrosion.
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A major problem of corrosion phenomena in AADC systems is that usually there are many variables
like ammonia concentration, temperature level, existing impurities, possible pre-treatment of the
surface, etc. which can greatly influence the corrosion rate. This is important because even low
corrosion rates have to be avoided because of the accompanied formation of non-condensable gases,
which influence the thermodynamic cooling process negatively. Possible gas forming reactions are:
(4) Fe + 2 H2O Fe(OH)2 + H2
(5) 3 Fe(OH)2 Fe3O4 + 2 H2O + H2 ('Schikorr reaction')
(6) 2 NH3 N2 + 3 H2
3.3.2 Consequences of the absence of corrosion inhibitors
AADC systems operated without corrosion inhibitors or with incorrectly adjusted corrosion inhibitor
systems can show serious corrosion induced damage from oxygen pitting, galvanic action, and crevice
attack. The absence of a suitable corrosion inhibitor or the use of an unsuitable corrosion inhibitor for
the respective AADC system could lead to equipment failure within a few months. Consequently, the
plant would have to be shut down for repairs for a time of at least several weeks. The H&R base oil
and wax production is intended to operate 24 h/day at 7 days/week without interruption (despite of
regular maintenance periods as described in the CSR).
A discontinuation of the use of sodium dichromate will lead to unsafe operating conditions because
heavy pitting will occur. Consequently, the cooling system is not functional and can no longer be
operated. Both refineries are joint productions, where the production processes are interdependent in
order to make use of all side products (just as the waxes and base oil) and energy streams (excess
heat/cold, waste water) that are generated. In fact, the process step of de-waxing/de-oiling is a key
process in the refineries and essential for most products generated there and therefore unavailability
of the required cooling capacity will lead to a complete standstill of the refineries because the key
products cannot be generated without cold.
A longer production stop would entail high losses in capacity with immense economic impacts, as
described in the next chapters and in the SEA. These problems are accompanied severe occupational
threats as a result of leaking tubes and pipes which are operating under immense pressure and high
temperature. Although replacement costs for material and labour are one important cost factor, the
reduced plant efficiency would create costs as a result of a lowered output and a reduced product
quality.
3.3.3 Corrosion inhibition with sodium dichromate
Corrosion resistance in the context of this application refers to the ability of carbon steel incorporated
in the AADC system to withstand gradual destruction by electrochemical reaction with its
environment. For the given application, inhibiting electrochemical destruction is the crucial for
assuring the longest possible life cycle of the AADC system and all its implicit parts. Corrosion
inhibitors can be categorized according to basic quality criteria which are inhibitive efficiency,
versatility, and toxicity. Furthermore, chemical and thermal product stability as well as quality of the
corrosion inhibitor have to be guaranteed. The use of sodium dichromate has proven to be essential
in the AADC system due to its excellent corrosion resistance and in situ repair properties regarding
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the conditions (e.g. basic medium, temperature, and flow rates) under which the system is operated.
Strong oxidizing corrosion inhibitors such as sodium dichromate form a protective layer on the metal
surface containing mainly trivalent chromium, oxidized iron and oxygen, as described by the
following equations:
(7) Na2Cr2O7 + 2 NaOH 2 Na2CrO4 + H2O
(8) 9 Fe + 8 Na2CrO4 + 8 H2O 3 Fe3O4 + 4 Cr2O3 + 16 NaOH
Under the given conditions predominating in the AADC units, the use of sodium dichromate is critical
for the formation of a stable and dense protective layer. Only at temperatures > 230 °C, the formed
protective magnetite film is strong enough ('Schikorr reaction') to prevent corrosion without addition
of a corrosion inhibitor as then the erosion-corrosion rate is low enough.
In summary, the main characteristics of sodium dichromate as corrosion inhibitor in the given cooling
unit are to build up a dense protective layer at temperatures between 35-165 °C. The protective layer
needs to be formed in the absence or at minimal concentration of oxygen, as non-condensable gases
in the working fluid ('cooling medium') reduce the cooling capacity drastically. The (erosion)
corrosion rate is dependent on (local) liquid velocities; i.e. the higher the velocity, the higher the
corrosion rate. Furthermore, the facility has at the 'poor solution' (11-12 % ammonia) a pH of 9.0 -
10.0 which cannot be changed. For the 'rich solution' (about 26 % ammonia) pH is around 12. An
overview of the most important process parameters and the requirements a corrosion inhibitor in
AADC systems has to fulfil is given in Table 6.
Table 6: Important parameters and functionalities of sodium dichromate as corrosion inhibitor
Criteria Definition / Justification Functionality
Verification
method /
minimum
requirement
(Active)
Corrosion
resistance
Corrosion resistance
describes the ability of the
steel parts used in the
AADC system to withstand
gradual destruction by
electrochemical reaction
with its environment.
The main functionality of
sodium dichromate within
the system. A passivating
magnetite layer is formed
which acts as a barrier and
prevents corrosive
processes.
Corrosion
resistance has to
be ensured over
the whole
lifetime of the
AADC systems.
Non-
condensable
gases formation
The formation of non-
condensable gases has to be
avoided by the corrosion
inhibitor.
Gases would negatively.
impact the cooling
efficiency
Sodium dichromate reduces
the formation of gases like
hydrogen (H2) which are
generated during the
electrochemical corrosion
reaction of iron. (see
reactions (1) – (6))
Cooling capacity
stable over long
term.
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Criteria Definition / Justification Functionality
Verification
method /
minimum
requirement
Temperature
The temperature in the
AADC systems ranges from
35 °C to 165 °C.
Only above 230 °C the
protective magnetite film is
formed strong enough for
corrosion prevention
without addition of
corrosion inhibitors like
sodium dichromate as the
erosion-corrosion rate is low
enough; below 180 °C the
use of a corrosion inhibitor
is critical for the formation
of a stable, dense protective
layer.
Sodium dichromate retains
its functionality within the
given temperature range.
Functional at
35 °C to 165 °C
pH
The actual pH of the 'poor
solution' (11-12 %-wt
ammonia) is 9 - 10. For the
'rich solution' (about 26 %-
wt ammonia) the pH is
around 12.
Sodium dichromate retains
its functionality within the
given broad alkaline pH
range.
Functional at
alkaline pH
Liquid velocity
The (erosion) corrosion rate
is dependent on (local)
liquid velocities. The
velocity varies within the
cooling system.
Sodium dichromate is able
to form the protective layer
at high local liquid
velocities.
Functional at
broad range of
liquid velocity
Oxygen content
An AADC system is
designed as a closed system.
Therefore, the oxygen
content of the working fluid
('cooling medium') is
considered to be very low.
Oxygen in the AADC
system would have a
negative impact the cooling
efficiency. Sodium
dichromate is able to form
the protective layer in the
absence of oxygen.
Functional in the
absence of
oxygen
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Criteria Definition / Justification Functionality
Verification
method /
minimum
requirement
Fouling
Fouling within the AADC
system has to be minimized.
Fouling reduces the cooling
efficacy and causes other
problems such as
contamination and cleaning
procedures.
If the corrosion inhibitor
also inhibits fouling
processes no additional
inhibitor has to be added.
Sodium dichromate shows
effects against
microorganisms and has the
potential to reduce fouling.
Not quantified
Long-term
stability of the
corrosion
inhibitor
The corrosion inhibitor must
be stable and active over a
long time as it is present
within the AADC system
for decades.
Should not interfere with the
water and the ammonia in
the AADC system or the
AADC system at all,
besides forming the
passivation layer. No
undesired long-term effects
on the AADC system should
occur.
Sodium dichromate has a
proven track record of many
decades to be an effective
and safe corrosion inhibitor.
Use in AADC
H&R’s systems
for a time period
of at least 20
additional years
Adsorption/
desorption
process
Influencing the
absorption/desorption
process would influence the
efficiency of the cooling
process.
Sodium dichromate does not
affect the absorption
desorption process in an
inadequate manner.
Performance
tests; long-term
experience
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Criteria Definition / Justification Functionality
Verification
method /
minimum
requirement
Proven
technology – for
application at
high
temperature in
desorber, very
low oxygen
content, water
rich material,
high velocity
The corrosion inhibitor must
show demonstrable
suitability for AADC
systems. Otherwise severe
security risks could occur.
This includes the leakage of
ammonia, which is not
acceptable in terms of
occupational and
environmental protection.
Furthermore, plant
shutdowns would have
severe economic impacts
(see SEA).
To date, sodium dichromate
has been used for decades in
the plant – no corrosion
issues have been observed.
Redox potential
half-cell
Information on the annual tonnage of sodium dichromate used as corrosion inhibitor in AADC
systems operated by H&R in Hamburg and Salzbergen (Germany) is provided in Chapter 4. Chapter 5
gives an overview of efforts in R&D concerning the identification and implementation of possible
alternatives to sodium dichromate as well as related approval processes. Section 5.3 provides a list of
identified possible alternatives.
4. ANNUAL TONNAGE
Sodium dichromate is used in both AADC systems operated by H&R in Hamburg and Salzbergen
(Germany). The annual tonnage is xxxx (≤ 0.01 tonnes) sodium dichromate [xxxxxxx as Cr(VI)].
During the past 17 years (2000–2017), xxx tonnes sodium dichromate, which is equivalent to xxxx
tonnes hexavalent chromium [Cr(VI)], were purchased by H&R and consumed in the specific use
applied for. The whole amount mentioned above was purchased at one occasion in 2017 and used to
refill the AADC system in Salzbergen. In the former years (2000 -2016) no concentration adjustments
took place. For more details please refer to the CSR.
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5. IDENTIFICATION AND IMPLEMENTATION OF POSSIBLE ALTERNATIVES
5.1 Description of efforts made to identify possible alternatives
Several efforts were made during the last years to identify possible alternative corrosion inhibitors
for AADC systems. In course of these efforts, scientific literature was evaluated extensively and
experts from other companies dealing with similar cooling systems were approached. Moreover,
several other international research institutes were contacted for the Arlanxeo AfA to discuss and
evaluate the state of the art for corrosion inhibition in this type of cooling systems. Besides that, H&R
had consultations with the manufacturer of the AADC systems.
This AoA includes expert opinions from downstream users, manufactures, academic and scientific
institutions and societies to set up a comprehensive documentation on corrosion inhibition in AADC
systems and associated cooling systems.
5.1.1 Research and development activities
The field of corrosion and corrosion inhibition was extensively investigated during the last decades
by industry and scientific institutions and is due to its economic impact still of particular interest.
Corrosion inhibition techniques were investigated for the purpose of this AoA based on extensive
investigation in course of the Arlanxeo AfA, for which the applicants hold a Letter of Access (LoA).
In this context, relevant literature and databases were screened, and experts, the AADC system
manufacturer and other industrial users, were contacted. Furthermore, a third-party consultancy and
a national research institute were consulted.
For the present document this information was combined with the insights H&R gained through their
own activities. The alternatives assessed for the Arlanxeo AoA were evaluated for H&R’s specific
case, as the key functionalities differ slightly in the quantitative dimension. Both, the Arlanxeo and
the H&R AADC systems are from the same manufacturer and, besides deviations in design, function
in the same way, which is why the insights from the Arlanxeo AoA can be regarded as adequate base
for H&R. And of course, the purpose of sodium dichromate is exactly the same.
The information on alternatives form the Arlanxeo AoA was assessed on being up-to-date in a
literature desktop study conducted by H&R. Several databases were searched for new publications.
The search revealed that between 2015 and today ground-breaking achievements were not made in
context with corrosion protection in AADC systems. The alternative assessment below therefore still
represents the latest stage of knowledge and development.
Other highly relevant sources of information are the publicly available AfAs of companies which
have applied for the use of sodium dichromate in AADC systems earlier, such as the AfAs submitted
by Jacobs Douwe Egberts DE GmbH (2016), TOTAL Raffinerie Mitteldeutschland GmbH (2016),
Dometic GmbH (2015) and Borealis Plastomers B.V. (2016).
5.1.2 Consultations and directed communications
H&R consulted the manufacturer of the AADC systems in Hamburg and Salzbergen to find out
whether an alternative to sodium dichromate was available. The manufacturer has the required
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competence to provide reliable information regarding this question. While H&R operates the AADC
systems, it is the manufacturer that conceptualises them and also provides the operating instructions,
including how to maintain the system to achieve a maximum lifetime of the system under safe
operation conditions. Part of this is also the use of sodium dichromate as corrosion inhibitor. The
technical and economic feasibility of alternatives that were initially discussed in context with the
Arlanxeo AfA, were discussed with the manufacturer of H&R’s systems. The knowledge gained in
this consultation are included in the alternative assessment in Chapter 6 below.
Furthermore, information on the status of alternatives was collected in consultations earlier by
Arlanxeo in course of their AfA, to which H&R holds a LoA. The extensive information derived in
this context must not be disregarded in order to assess alternatives for H&R in a comprehensive way.
Therefore these consultations and directed communications are recapitulated in the following:
In 2003 consultation of various chemical companies, water technology companies and the Materials
Technology Institute (MTI) for information of potential alternatives to sodium dichromate in AADC
systems were conducted. Furthermore a company was identified that had used molybdate as an
alternative but had switched back to sodium dichromate due to massive corrosion problems. In 2009
the above mentioned survey was repeated by Arlanxeo’s corrosion specialists and additionally two
suppliers of ammonia vapour absorption installations were contacted. In 2015 a water
technology/treatment company was invited to assess alternatives. Also specialized research institutes
for cooling engineering were approached. An extensive literature study had already been conducted
in 1999. This literature was assessed for this AoA and taken into consideration, where applicable. In
another third-party study, conducted in 2015, the report from 1999 was reassessed and complemented
based on updated scientific information, information requests in an international scientific forum and
most importantly discussion with downstream users and manufactures.
Finally, the company Dometic Holding AB (Dometic), a manufacturer of small scale cooling systems,
which has also filed an AfA for sodium dichromate as a corrosion inhibitor for AADC systems, was
contacted. The company has a promising proprietary alternative corrosion inhibitor for the small scale
absorption cooling units (e.g. for minibars, recreational vehicle refrigerators and medical cold
equipment) they produce under development. Long-term performance tests are being conducted by
Dometic and will, according to the AfA, continue for several years. The consultation revealed that so
far it is not known how this alternative would perform in AADC systems on much larger industrial
scale. No tests have been conducted because the substance is not available to the public. The long-
term performance of the proprietary system is apparently still under review. (Dometic GmbH, 2015).
All in all, none of the consultations led to the identification of a feasible alternative for sodium
dichromate for Arlanxeo’s AADC systems (further details are provided in the Arlanxeo AfA
(Arlanxeo Netherlands B.V., 2015)).
Against the background of these R&D efforts, no alternative corrosion inhibitor has proven technical
or economic suitability in ammonia water based cooling systems by today. To provide a substantiated
argumentation, a detailed discussion of several possible alternatives that were also included in the
Arlanxeo AfA is described in Section 6.3 specifically in relation to H&R’s AADC systems. Most
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important, only very limited experience exists with regard to the real-life use of alternative corrosion
inhibiting substances in AADC systems.
5.2 Overview on the process of alternative development and industrial implementation
For many decades, AADC systems made of carbon steel have constituted a safe and reliable cooling
technology for miscellaneous industry sectors. Safety and reliability was ensured by using sodium
dichromate as corrosion inhibitor enabling high performance under specific process conditions.
Indeed, scientific and technical research was performed over the last years suggesting a variety of
replacement corrosion inhibitors in literature. Different patents are available, describing corrosion
inhibitor alternatives for AADC systems.
Nevertheless, most alternatives discussed in scientific and technical literature have in common that
they were not tested under realistic conditions in large-scaled systems and for a realistic time span.
Scientific results on corrosion inhibition are often gained from tests with metal stripes, exposed to
chemicals in autoclaves for a short time or in lab-scale cooling devices. Such results are not
necessarily comparable to cooling units with several thousand kW cooling power. This is also stated
by a company in this sector which gained extensive experience during years of testing on test vessels
and on actual machines incorporating an absorption refrigeration cycle. It was concluded that there is
no simple relationship between tests carried out in simulation vessels and those under real machine
conditions. Generally, good behaviour of a corrosion inhibitor in simulation vessels does not imply
that it will automatically operate well on a real machine. Tests on simulation vessels can therefore
only be used as preliminaries to select families of products to be tested (Guerra 2003).
For the development and industrial upscaling of a possible alternative for sodium dichromate as
corrosion inhibitor for ammonia absorption systems made of carbon steel, several phases bringing an
alternative step by step to final application would be necessary to ensure a safe use over of the
expected life time of the cooling plant (up to 50 years).
Phase I: Identification of alternatives and implementation on a laboratory-scale
As a first step, alternatives to dichromate-based systems have to be identified and evaluated. Detailed
description of possible alternative substances is provided in Section 6.3 of this AoA. The efforts show
that the information available is of heterogeneous quality. This initial development phase is dedicated
to screen those alternatives potentially applicable within the pool of available substances and
techniques. Sources for such a screening are: literature studies, patent examinations, the evaluation
of existing solutions in other areas, competitor analysis, and of course the information gathered in
course of the preparation of this AoA must also be taken into account.
As a second step of phase I, potential alternatives have to be tested extensively at the laboratory level.
It has to be assured whether the different components of the alternative corrosion inhibitor system
work together properly or not. Throughput time for producing and testing a sample is in the order of
weeks; there is no specific overall throughput time for the screening phase as it varies largely with
the number of alternatives tested. Multiple iterations are often needed before a promising set of
alternatives is defined after having passed the test requirements at this stage. For initial laboratory
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testing, simple test vessels can be used in this phase. This allows no detailed but a rough comparison
of the tested alternative systems. The testing of samples is done according to several standardized
methods. First, the quantity of the active corrosion inhibitor has to be measured, then performance
needs to be checked by some relevant analytical methods. The current corrosion inhibitor (sodium
dichromate) should be incorporated in the testing as a reference in order to compare samples that are
produced in different laboratories or at different times.
Phase I may require iterative processes to refine identified alternatives and time needed heavily
depends on testing capabilities. The process is completed with the setup of a pilot system to be further
evaluated in the up-scaling phase. According to an expert opinion from a research institute for cooling
engineering, many potential alternatives are described in literature, but there is still no satisfying drop-
in alternative available for industrial use in ammonia based cooling systems. It is highly
recommended to start a project on European Union (EU) level with experts from industry, academics
and associations to investigate the implementation of alternative corrosion inhibitors in different types
of cooling systems. For setting up such a project, a lead time of one year is necessary to define scope,
members and milestones and to draft the project structure. The according identification and validation
step of potential alternatives takes at least 3 - 6 years and entails costs between EUR 300 000 to EUR
500 000.
Phase II: Up-scaling and test in relevant environments
After identifying and testing potential alternatives on the laboratory scale, reproducibility of those
corrosion inhibitor systems has to be proven on the application level of the specific use. Therefore,
the pilot system has to be up-scaled and validated in the relevant environment (e.g. varying cooling
temperatures or performance). Monitoring of robustness and stability of the process using the
alternate corrosion inhibitor must be carried out closely. As an example, this step had been performed
for more than 8 years by Dometic for their, compared to H&R’s systems, small scale applications
(Dometic GmbH, 2015).
Furthermore, the validation of the up-scaled pilot systems includes checks for approvals by authorities
concerning plant and process safety. Phase two will take additional 7 years if no major drawbacks
occur and will generate costs in the same range as Phase I between EUR 300 000 to EUR 500 000.
The challenge in this step is, that unintentional, uncontrolled release of ammonia needs to be avoided
by all means, which is why close long-time monitoring is essential, at least for 1 to 5 years for small
scale applications (Dometic GmbH, 2015). Altogether, 7 years the minimum time needed for the
completion of Phase II.
Phase III: Implementation on existing facility
In the last phase, the outcome of Phase I and II has to be implemented or adapted into the existing
AADC systems operated by H&R. Systems may have to be partly reconstructed and modified to
facilitate drop-in alternatives. In H&Rs case, the timeframe for such modifications with the lowest
impact on production, is the time of the regular maintenance window of the AADC system, which is
conducted every five years.
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After the implementation, monitoring of robustness and stability of the process by using the alternate
corrosion inhibitor under the industrial circumstances is considered necessary, as long time
experience must be gained with any alternative to ensure a safe and reliable operation and functioning
of the system and the absence of corrosion and pitting. The monitoring needs to be conducted over a
long time period, ideally at least until the next maintenance of the subsequent production line takes
place after 5 years.
In this context it is of utmost importance to have the possibility to keep the system running in case
the (technical or chemical) alternative fails. For this purpose, the sodium dichromate must be
available as corrosion inhibitor until the reliability of an alternative has been proven.
An illustration of the development process including the above described phases I-III can be found in
Figure 8.
Figure 8: Expected timeframe of sodium dichromate substitution in the AADC systems in Hamburg and Salzbergen (Germany)
As clearly outlined, passing Phase I and II will take up to 15 years. Assuming that initiatives will start
in 2017, it is anticipated that the process can easily take until 2032. The next maintenance window
for the connected production plant, which is accompanied by a temporary production stop, will also
take place in 2032 (five year rhythm with the latest window in 2017). At least another five years are
required for performance monitoring, adding up the overall required time to 20 years. Besides this, it
has to be taken into account that the remaining life time of the AADC systems operated by H&R is
at least 35 years (Hamburg) and at least 20 years (Salzbergen)1. Therefore, end of operation of these
AADC systems is estimated for the years 2037 to 2052 respectively.
The challenging issue in this context is evident in the fact that H&R is the operator but not the
manufacturer of the AADC systems, and downstream user of sodium dichromate as corrosion
1 The AADC systems were installed at different times. The system in Salzbergen was installed in 2000 while the one in
Hamburg was installed in 2012. AADC systems can have an overall lifetime of more than 50 years.
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inhibitor. While H&R indeed operates the existing systems safely, their core business is not the
conception and design of AADC systems. This competence lies at manufacturers of such systems,
which H&R relies on in this context. The ability to research and develop an alternative corrosion
inhibitor “from scratch” in the necessary dimension is on the other hand more a topic for scientific
research. Nevertheless, it is clear that a solution needs to be found. H&R is aware of their
responsibility as operator of AADC systems to contribute to the quest with all the possibilities they
can offer. This includes the willingness to become involved in research wherever their competences
and facilities can be of help, continuation of desktop research to stay on track with developments and
close follow-up on activities of other operators and suppliers of AADC systems as well as ongoing
research. In any case it is in the interest of H&R to contribute to increase the knowledge about the
reliability of promising alternatives in the long term use. Especially after the assessment of promising
alternatives on small scale in Phase II, H&R could contribute in the testing in large scale facilities
under realistic conditions and in Phase III, when it comes to the actual implementation of an
alternative into real-life systems and the required monitoring throughout the following years.
5.3 List of possible alternatives
As a result of the efforts described in Chapter 5, the most promising alternative corrosion inhibitors
are discussed in the following chapter. Beside the one-to-one replacement of the corrosion inhibitor,
the impacts of a complete technology change, such as the implementation of a Vapour Compression
Cooling (VCC) system will be elucidated in the following Section 6.1. Additionally, it will be
discussed if a replacement of specific corrosion prone parts of an AADC systems is suitable to
ensure a safe and reliable performance of the system (see Section 6.2). The evaluation of alternative
corrosion inhibitors is described in Section 6.3.
The potential alternative substances are classified according to their relevance as Category 1 or
Category 2 alternative. An overview is provided in Table 7. In case of Category 1 alternatives, initial
R&D efforts on ammonia/water based systems can be found. Although partly tested on test vessels
or commercially available small scale units, they are far away from being applied on the industrial
scale. Respective R&D is mostly of basic nature than ongoing. Category 1 alternatives are discussed
in detail in the following Section 6.3.2.
As for Category 2 alternatives, only indications for the use as corrosion inhibitor for carbon steel was
found in the course of the literature review. Results are restricted to the laboratory scale and no
indication for the use in AADC systems is present. In addition, Category 2 alternatives exhibit
technical limitations leading to dismissal. Category 2 alternatives are therefore only tabulated in
Appendix 1.
Table 7: Categorized list of alternative corrosion inhibitors
Chapter Cr(VI) free corrosion inhibitors
Category 1
6.3.2.1 Molybdate
6.3.2.2 Sodium nitrite
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Chapter Cr(VI) free corrosion inhibitors
6.3.2.3 Silicates and water glass
6.3.2.4 Zinc containing corrosion inhibitors
6.3.2.5 Strong alkaline solutions
6.3.2.6 Phosphates and phosphonate compounds
6.3.2.7 Rare Earth Metal Salts (REMSs)
Category 2
Appendix 1
Tartrate compounds
Benzoate
Glutamate
Succinic acid
Organic inhibitors
Azole and azolines
6. SUITABILITY AND AVAILABILITY OF POSSIBLE ALTERNATIVES FOR THE
AADC SYSTEMS OF H&R
As mentioned above, H&R operates two AADC systems applying sodium dichromate as corrosion
inhibitor in their refineries in Hamburg and Salzbergen (Germany).
For the three AACD systems, 3 different alternatives are discussed:
- Section 6.1: Replacement (change) of the cooling system
- Section 6.2: Replacement of corrosion prone parts
- Section 6.3: Substitution of sodium dichromate as corrosion inhibitor
6.1 Alternative 1: Replacement (change) of the cooling system
6.1.1 Properties/Description
VCC, a technique where the refrigerant undergoes phase changes, is widely used for cooling and air
conditioning, e.g. in automobiles, buildings, refrigerators, oil refineries and chemical processing
plants. Generally, in such a cooling system the enthalpy of vaporization occurring at the liquid
gaseous transition is used for cooling effects. In most cases, VCC units do not depend on the use of
a corrosion inhibitor system.
6.1.2 Technical feasibility
VCC systems have cooling capacities of a few Watts (W) to several MW. Accordingly, a VCC
system is potentially able to provide enough cooling load for H&R’s plants in Hamburg and
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Salzbergen (Germany) which require xxxxxxxx. Temperatures down to about -30 °C are required.
VCC systems can provide the required cold and reach temperatures down to -40°C.
Differences between the two technologies, AADC and VCC systems, are listed in Table 8.
Table 8: Advantages of the two cooling technologies
VCC systems AADC systems
Better dynamics
Low heat release / heat dissipation
Heat as energy source is available at the
applicants’ sites from other processes
Extraordinary good partial load behaviour
Low consumption of electrical energy
Robust, reliable and long-lasting technique
Low maintenance effort required
When the old compression systems were to be replaced, cost-efficiency, which is in this aspect closely
connected to resource efficiency, was a main argument to implement AADC systems in 2000
(Salzbergen) and 2012 (Hamburg).
Furthermore, to switch to a VCC system the whole cooling system with all its components, vessels,
pipelines, control units must be exchanged. The AADC systems run by H&R are of enormous size
and complexity. Also the complexity of a VCC system is high, posing serious challenges for the de-
construction of the old and building of the new system.
On the other hand, H&R has experience with VCC systems, since they are used for other purposes
on the sites in Hamburg and Salzbergen, and before the AADC systems were implemented, VCC
systems were used in the production of base oil and waxes. So, all in all VCC systems are considered
to be technically feasible.
6.1.3 Economic feasibility
The economic impacts of a transition from AADC towards VCC are discussed as non-use scenario
(NUS) 1 in the SEA. The findings from the SEA are summarised here. For more detail please refer
to the SEA.
For the installations at H&R’s sites, the use of a VCC installation instead of an AADC installation
would mean a complete replacement of the existing technology. The site development does not allow
to build a new cooling plant additionally to the existing one, due to space limitations. The existing
cooling plant would have to be destructed first before a new one can be constructed. Due to the fact
the site is located in the vicinity to a residential area, costs for housing and a building for noise
protection must also be included.
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H&R expects that the current cooling systems (using ammonia absorption technology), could last for
at least 20 years more with very few routine maintenance efforts. For this reason, the purchase of a
new cooling system would bring forward an investment that otherwise would only happen in 20 years.
The new cooling system is expected to last for 20 years after and therefore, the calculation of the
annual cost of this investment was done considering this period as the total lifetime, 20 years of earlier
investment and xxxxxxxxxxxxx as the total amount required to purchase the new equipment. Since
the lifetime of the new equipment is assumed to be exactly the same as the remaining life of the old
equipment, the net present value (NPV) was calculated considering 20 annual payments, therefore
resulting in an NPV that amounts exactly to the total amount of the investment: xxxxxxxxxxxxxxx.
Another factor that adds to the economic impacts in case of non-authorisation is the production
downtime caused by the implementation of the new cooling system. H&R expects that the
implementation process of the new technology would take approximately 2 years. Meanwhile the
new cooling system is implemented, production lines will have to be shut down resulting in
opportunity cost for the company. The total duration while the production would have to be stopped
is estimated to take xx days. The plants are running at full capacity and continuously (24 hours/day,
7 days/week), not being able to replace the cooling system without a production stop. The calculation
of the opportunity cost during this period was done using the added value foregone. The calculations
in the SEA reveal that a total of xxxxxxxxxxxx in value added foregone need to be added to the
economic impacts in H&R’s case.
Additionally, H&R has analysed its future cooling costs in the case the new cooling system would be
installed. Considering the whole period of assessment (20 years), the NPV of the additional annual
costs for this period is an indicator of the economic benefit of switching to the alternative. The NPV
of these yearly additional costs over a period of 20 years sums up to xxxxxxxxx.
Summing up all economic impacts that would arise from the switch to VCC (new investment, loss of
capacity, downtime) and deducting the amount that would be saved due to reduction in the production
costs, the net economic impacts of the NUS can be summarised as follows in Table 9.
Table 9: Net Economic Impacts – replacement (change) of the cooling system
Type of impact [EUR]
Investment in a new cooling system xxxxxxxxx
Value added foregone due to downtime xxxxxxxxx
Additional operational costs with VCC xxxxxxxxx
Net economic impacts 40 400 313
6.1.4 Reduction of overall risk due to transition to the alternative
The overall risk associated with a complete replacement of the cooling technology depends on the
particular technology used. Since, to the current state of knowledge, the information collected by
H&R on this topic and not at least due to practical experience at H&R with big VCC systems in their
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refineries, no corrosion inhibitor, and thus no sodium dichromate, is required for VCC systems.
Therefore the use of a VCC system would eliminate the risk from the use of sodium dichromate.
6.1.5 Availability
The general availability of VCC systems is not regarded as critical, because different companies do
offer the manufacturing of such systems. However, regardless of the fact that an exchange in the next
years is not advisable from an economic point of view, the practical installation of VCC systems
poses serious challenges. The whole cooling system with all its components like vessels, pipelines,
control units etc. would need to be exchanged completely. The AADC systems of H&R are highly
complex and of enormous size. The installation of equally large and complex VCC systems poses
serious challenges, because of the restricted availability of free space on the refineries’ sites, which
is why the old system would have to be deconstructed before the new system could be built (see also
section economic feasibility).
6.1.6 Conclusion on suitability and availability
Even though technically feasible, the installation of a VCC system would be accompanied with
considerable economic impacts such as investment costs, downtime of production, decreased
production capacity. On the other hand, operational costs could be reduced with the new system.
From a technical perspective, for the current AADC systems fewer maintenance efforts are needed
and these cooling systems generally possess a longer overall lifetime (10–20 years vs. up to 50 years).
Overall, to date change to a VCC system is not considered to be an applicable alternative for H&R
for economic reasons.
6.2 Alternative 2: Replacement of corrosion prone parts
6.2.1 Properties/Description
The replacement of corrosion prone parts of the existing AADC systems with components that are
more corrosion resistant, e.g. stainless steel could be another possibility to prevent material
degradation. Here only parts of the existing cooling units in Hamburg and Salzbergen would have to
be replaced.
6.2.2 Technical feasibility
Literature research showed that stainless steel is often discussed as being corrosion resistant to
ammonia water based systems. Whether the replacement of parts made of carbon steel by stainless
steel allows operating the AADC system reliably without sodium dichromate was investigated for
this AfA.
A replacement would be needed at least for the most corrosion prone parts, which are in contact with
cooling medium at high temperature. It was discussed whether these parts should be made of stainless
steel to reduce corrosion. The remaining parts that are in contact with concentrated ammonia could
remain constructed in carbon steel. Parts that would be needed to be replaced H&R’s AADC systems
are, at least, the desorber, the solution heat exchanger and corresponding piping till as well as the
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absorber condensers, all constructed in carbon steel and to be replaced by new equipment/piping in
stainless steel. Beyond this it has to be investigated if absorbers itself maybe do not need to be
replaced, due to lower temperature and overall milder corrosion conditions. Since the applicant’s
AADC systems are large and complex, the practical work to exchange of the parts poses a serious
challenge.
Beside stainless steel also carbon steel equipment which is permanently coated by a passivating layer
was discussed as an option. Such techniques are commercially available, but this would as well
implicate the replacement of large parts of the AADC system.
To discuss the feasibility of this approach, the manufacturer of H&R’s systems was contacted by
H&R to gain insight on the latest state of knowledge in this context. The statement received (see
confidential Appendix 3) on this issue says that:
1. Materials with better, maybe even sufficient, corrosion resistance are not widely spread within
large AADC systems.
2. However, the idea is promising from a technical standpoint, but no long term experience is
available.
This is supported by the investigations conducted by Arlanxeo for their AfA, where a German
research institute was also contacted for this purpose. The research institute concluded that stainless
steel systems of a size similar to the Arlanxeo AADC, which is of a comparable dimension to H&R’s
systems, are currently not operated and, even more important, no reliable conclusion about the
presence or absence of corrosion inhibitors in such systems can be drawn.
As already mentioned in Section 3.3, the use of carbon steel in AADC systems is preferred due to
economic advantages and better machinability. Further literature research substantiated the
statements above, revealing that results on corrosion resistance of stainless steel in ammonia water
based systems are not consistent. Several authors described corrosion problems on stainless steel and
chrome plated steel when tested in ammonia water based systems (Mansfeld and Sun, 2003; Griess
et al, 1985). These results were also heavily influenced by the process temperature. With higher
temperatures, corrosion rates increased significantly (Behrens 1998, Kreysa and Schütze 2007).
Recently, Moser et al. (2011) investigated the hydrogen production rate in two test facilities (stainless
steel and carbon steel) for ammonia water based absorption heat pumps at different temperatures as
a marker for corrosion performance. It was shown that mild carbon steel (ST37) induced lower
hydrogen production than stainless steel.
Generally, it can be concluded, that also stainless steel is subject to corrosion in ammonia water based
systems, especially at higher temperatures. As mentioned above, at present, no information exists on
corrosion inhibition for systems made of stainless steel.
6.2.3 Economic feasibility
The economic impacts of a transition from AADC towards VCC are discussed as NUS 2 in the SEA.
The findings from the SEA are summarised here. For more detail please refer to the SEA.
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The investment costs for stainless steel parts would be xxxxxxxxxxxxxxxxxxxx for one cooling
system (equipment costs only). This does not include labour costs for deconstruction and construction
of the new system. An engineering factor of 3 needs to be added to the cost estimate for a replacement
of the entire cooling system. This engineering factor is needs to be applied to arrive at a realistic
estimate of the total cost to replace the corrosion prone parts of the system.
H&R expects that the current cooling system (using ammonia absorption), could last for 20 years
more with very few routine maintenance efforts. For this reason, the purchase of new equipment
would bring forward an investment that otherwise would only happen in 20 years. Since there is
absolutely no experience available with stainless steel parts in AADC systems in the industrial scale,
the lifetime of this equipment cannot be estimated, but is expected to be considerably shorter than the
current one. However, to keep the worst-case approach, 20 years of functional lifetime of the
stainless-steel parts are taken as input for the following calculations. In addition, it is expected that
due to the lack of experience, the costs for routine checks and maintenance will be considerably higher
than with the current system, but also these costs were not factored in here.
The new equipment is expected to last for 20 years. Therefore, the calculation of the NPV of this
investment was done considering 20 years of total lifetime, 20 years of earlier investment and xxxx
xxxxxxxxxxxxxxxx as the total amount required to purchase the new equipment, dismantle the
existing one and install the new equipment.
Since the lifetime of the new equipment is exactly the same as the remaining life of the old equipment
(conservative assumption), the NPV was calculated considering all the 20 annual payments, therefore
resulting in an NPV that amounts exactly to the total amount of the investment, xxxxxxxxxxxxx
xxxxxxxxx.
Similar to NUS 1 – change to another cooling system – the expected minimum downtime for the
replacement of parts by stainless steel parts is xx days. Therefore, the economic impact resulting from
the downtime in the NUS – replacement of parts – is the same as in the abovementioned scenario 1.
The monetised impact in this case is xxxxxxxxxxxxxxxxx.
In sum the net economic impacts for the replacement of corrosion prone parts can be summarised as
follows in Table 10.
Table 10: Net Economic Impacts – replacement of corrosion prone parts
Type of impact [EUR]
Investment in a new cooling system xxxxxxxxxxxxxxxxxxxx
Value added foregone due to downtime xxxxxxxxxxxxxxxxxxxx
Net economic impacts 16 301 935 – 22 301 935
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6.2.4 Reduction of overall risk
For the assessment of environmental and human health related risks associated with a replacement of
corrosion prone carbon steel parts with stainless steel parts an external technical expert review was
carried out in course of the Arlanxeo AfA. Based on these information, it was stated that such a
replacement had never been performed for large ammonia water based cooling systems in the past.
As evaluated in the section on technical feasibility (6.2.2), it is not known whether a modified AADC
system, with replaced metal parts, could run in a safe and reliable manner without additional corrosion
inhibitors. Moreover, no experiences exist which parts have to be replaced. There is a substantial risk
remaining that not all necessary parts are replaced. For risk mitigation in terms of safety, the use of a
corrosion inhibitor in a modified AADC system seems essential.
In summary, no reliable experience exists on the safe long-term operation of an AADC system made
of stainless steel of the size operated by H&R in Hamburg and Salzbergen (Germany). It is not known,
whether a corrosion inhibitor has to be used within these systems. If the risks are not properly
controlled, this could lead to accidents and the uncontrolled release of up to 100 % ammonia into the
environment with severe impacts on environment and human health.
6.2.5 Availability
All necessary parts of the AADC system could be built with stainless steel, which is substantiated by
the information provided by a manufacturer of cooling units. Availability is therefore not considered
as critical.
6.2.6 Conclusion
From the current state of knowledge, the replacement of critical parts cannot be regarded as
technically feasible for H&R’s AADC systems in Hamburg and Salzbergen. There is no long-term
experience whether an ammonia water based cooling system made of stainless steel can be operated
in a safe and reliable manner with or without adding a corrosion inhibitor. It is likely that a partial
replacement of corrosion prone parts would still make the presence of a corrosion inhibitor
mandatory. Furthermore, this alternative would be an extremely expensive solution, due to the costs
of the replacement (material and labour) and the expected downtime of the system. And finally it is
not sure whether the overall risk would be reduced through this measure because it cannot be
guaranteed that all necessary parts are replaced and hence the risk associated with corrosion could
not be eliminated completely.
Overall, the replacement of specific corrosion prone parts is not considered as an alternative.
6.3 Alternative 3: Substitution of sodium dichromate as corrosion inhibitor
Especially for the alternatives substances discussed in the following, the Arlanxeo AfA provides
extensive information, which due to the similarity of the AADC systems run by H&R and the more
general nature of the information available to date, can be considered valid for the present case as
well. According to the literature search conducted by H&R on the corrosion inhibitors, the alternative
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assessment from Arlanxeo therefore still represents the latest stage of knowledge and development
(see Section 5.1.1).
The substitution of sodium dichromate by another corrosion inhibitor would be the most reasonable
alternative to the use of sodium dichromate. It is mandatory that the alternative corrosion inhibitor
entails similar inhibition functions as already discussed in Section 3.3. The main parameters, assessed
for corrosion inhibitor alternatives are corrosion resistance (effectiveness of the corrosion inhibitor)
at carbon steel, prevention of gas formation, and effectiveness at temperature ranges of 35–165 °C,
effectiveness at alkaline pH of approx. 9–12 and effectiveness in the absence of oxygen.
The suitability of the candidates for replacing sodium dichromate as corrosion inhibitor in AADC
systems identified in Chapter 5 are discussed in the following section based on specific criteria.
Generally, most of the effectiveness tests on alternative corrosion inhibitors are performed in vessels
in which a sample of the metal to be tested, typically carbon steel, is brought to a similar temperature
and pressure to those at the critical points of the absorption cycle, it is then left under these conditions,
measuring the corrosion gases which develop, and finally the sample surface is also analysed.
Simulation vessels are used for cost reasons, so that an entire machine incorporating an absorption
cycle does not have to be used, often for thousands of hours, at each test on a new corrosion inhibitor.
During years of testing new corrosion inhibitors, experience from companies from the refrigeration
sector that conducted numerous experiments both on test vessels and on actual machines
incorporating an absorption cycle clearly demonstrated that there is no simple relationship between
tests carried out in simulation vessels and those under real machine conditions. Generally, good
performance of a corrosion inhibitor in simulation vessels does not imply that it will operate well on
a real machine. Tests on simulation vessels can therefore be only used as preliminaries to select
families of corrosion inhibitors to be tested. Consequently, this analysis will focus on alternative
corrosion inhibitors that are tested on machines incorporating an ammonia water based absorption
cycles and not on simulation vessels.
6.3.1 Technical requirements for corrosion inhibitors at the applicants’ sites
A range of different parameters have to be regarded to ensure the efficiency and security of the AADC
systems operated by H&R in Hamburg and Salzbergen (Germany). This includes the following:
General process-related requirements
In AADC systems corrosion inhibitors are used to prevent corrosion induced metal loss that could
lead to critical system failures in cooling equipment like heat exchangers or recirculating water
piping. The loss of structural integrity, is of high concern, particularly for the high pressure
components of the system, such as the desorber and condenser. Furthermore, corrosion reduces
cooling efficiency due to gas formation and corrosion products may precipitate on critical heat
transfer devices and thereby insulate the metals.
The corrosion inhibitor must entail long-term activity and reliability of corrosion inhibition for carbon
steel over the whole life-time of the cooling unit which is for several decades.
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
44
Information requirements for a corrosion inhibitor change
Before an alternative corrosion inhibitor can be considered as alternative, different substance
information has to be available. This includes e.g. vapour pressure, solubility in ammonia water
mixtures, rectification, volatility, absorption, toughness, heat transfer, flow properties, etc.
Additionally, the stabilization of these parameters within the system ammonia/water over a long time
period has to be ensured. Corrosion test are often performed in a few days within autoclaves to
simulate AADC systems. These results are often not directly transferable to large-sized industrial
facilities with several MW cooling power. As mentioned in Section 5.2, a comprehensive
development has to be carried out before an alternative substance can be considered as safe and
reliable for the use as corrosion inhibitor in an AADC systems.
6.3.2 Assessment of alternative corrosion protective substances: Category 1
Corrosion inhibitor alternatives described within this AoA are divided into two groups: Category 1
and Category 2 alternatives. Category 1 comprises alternatives where initial R&D efforts ammonia
water based systems can be found. Although partly tested on test vessels or commercially available
small scale units, they are far away from being applied on the industrial scale. Respective R&D is
mostly of basic nature and ongoing.
Furthermore, the following assessment of the feasibility of the presented alternatives contains
summarizing tables with a colour code. The colours are as follows:
General information on the alternative substances assessed in Category 1 (e.g. physico-chemical
properties) and the respective categorisation regarding risk to human health and the environment is
provided in Appendix 2.
6.3.2.1 Molybdate compounds
6.3.2.1.1 Substance ID and properties
Molybdate is an anodic corrosion inhibitor that has been used for many years as corrosion inhibitor
for carbon steel. By precipitating an inert barrier layer (ferric molybdate) on the metal surface,
molybdate is able to suppress the anodic action. The protective layers, which are not chemically
bonded to the surface, can be resistant to flow velocity and turbulence. If used together with a nitrite
the anti-corrosive performance can be enhanced.
Colour Explanation
Not sufficient – the parameters/assessment criteria do not fulfil the requirements
The parameters/assessment criteria fulfilment not yet clear
Sufficient – the parameters/assessment criteria do fulfil the requirements
No data available
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
45
Molybdate also helps to retard pit growth due to the release of absorbed molybdate which
concentrates inside the pit precipitating as condensed molybdate species (GE Power & Water, Rey
and Thompson, 2013). Molybdates have not been used as extensively because they are weaker
oxidizing agents than chromates. In general, higher concentrations of molybdate are required to
achieve the comparable results (Patent, 1999).
Downey (1995) describes in a United States (US) patent the use of a complex mixture as working
fluid in absorption cooling systems. The working fluid consists of halogen or ammonium salts of
molybdenum, boron and, in a preferred embodiment, silicon added to the aqueous solution. A
hydroxide of sodium, lithium, potassium or ammonium is also added to attain the desired alkalinity.
The author claims that this mixture is an appropriate corrosion inhibitor for working fluids containing
aqueous solution of at least one compound selected from the group consisting of lithium bromide,
lithium chloride and lithium iodide. No further details are presented, especially no information about
the used system, test duration or any other information about corrosion inhibitor efficiency.
Phillips et al. (1996) describe in a US Patent corrosion inhibition of alkaline bases at 25 °C and
concentrations of 0.015 N and 0.2 N, as discussed in Section 6.3.2.5. The patent specification
discusses borates, molybdates and acetates as combination partners to strong alkaline bases.
6.3.2.1.2 Technical feasibility
Corrosion resistance: Beside the test results from the laboratory scale, as described in the several
patents, real-life experience exists for the use of molybdates in an ammonia/water based cooling
system. The experiences clearly demonstrate (as explained in Section 5.1.2) that the use of molybdate
as corrosion inhibitor caused severe corrosion in the cooling system.
Effective at alkaline pH: Molybdate inhibits steel corrosion in near neutral pH and alkaline media
(pH 6 and above). The pH range is described to be ideal in between 6–10.
Effective in absence of oxygen: Molybdate is not an effective corrosion inhibitor in the absence of
oxygen. The anti-corrosion performance on ferrous metals is based on the formation of a protective
oxide layer. It was stated that generally, for a good corrosion inhibition with molybdate an oxygen
concentration of at least 1 ppm is required. Molybdate ions react with the ferrous ions at the anodic
site to form a non-protective ferrous molybdate complex (Raheem 2011).
6.3.2.1.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economically feasible. But it has to be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35-165 °C
Effective at
alkaline pH
(9-12)
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
46
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
6.3.2.1.4 Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Based on the available information on the substances used within this alternative (see Appendix 2)
Ammonium molybdate constitutes the worst case with a classification as Acute Tox. 4, Skin Irrit. 2,
Eye Irrit. 2, STOT SE 3, Aquatic Chronic 3, Skin Sens. 1 and Resp. Sens. 1. As such, transition from
sodium dichromate – which is a non-threshold carcinogen – to one of these substances would
constitute a shift to less hazardous substances.
However, if molybdate compounds would be used as corrosion inhibitor in H&R’s AADC systems
there would be an increased risk of uncontrolled release of ammonia into the environment.
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, the substance failed to prove suitable
performance for the safe and long-term use in AADC systems. Therefore, it is questionable if this
substance will be subject to further R&D. Generally, an extensive development process as described
in Section 5.2 would have to be passed successfully, before the substance could be reconsidered as
potential alternative.
6.3.2.1.5 Conclusion
In summary, molybdate compounds showed severe technical limitations in terms of corrosion
protection in AADC systems and effectiveness in the absence of oxygen. They cannot be considered
as an alternative corrosion inhibitor in AADC systems.
6.3.2.2 Sodium nitrite
6.3.2.2.1 Substance ID and properties
Sodium nitrite (NaNO2) is one of the most commonly used anodic corrosion inhibitor shifting the
corrosion potential to more noble values and reducing corrosion current and can be seen as ‘true’
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
47
passivating agent, because it encourages formation of a passive layer on steel without itself being
involved in the film. Sodium nitrite requires a critical concentration for the protection of carbon steel.
Sodium nitrite is used as corrosion inhibitor in coolants consisting of utility water in cooling towers
in the presence of chlorine. Sodium nitrite requires nitrite levels that are at least equal to that of a
possible chloride concentration and should exceed potentially present sulphate levels. Such towers
often contain carbon steel pipes which have to be protected against corrosion. First studies indicate
that sodium nitrite could be a suitable corrosion inhibitor in ammonia water based cooling systems
(Hayyan et. al. 2012).
Nevertheless, sodium nitrite is no possible alternative for the use in AADC systems due to its
chemical reaction with ammonia as reducing agent.
6.3.2.2.2 Technical feasibility
The protecting film is formed through the adsorption of the nitride ions followed by an oxidation step
resulting in a very thin film of typically 2E-03 µm.
Corrosion resistance: Potentiostatic experiments could show that the corrosion potential values are
in general nobler than those obtained under identical conditions in uninhibited solutions. Sodium
nitrite is described as good anodic corrosion inhibitor (Hayyan et al, 2012). Nitrite was also tested in
commercially available small scale ammonia/water refrigeration systems, but turned out to be inferior
compared to chromates. Nitrites are rapidly consumed at higher temperatures and their protective
layer is far less efficient.
Prevention of gas formation: During the corrosion inhibition process with sodium nitrite, no gas
formation is associated according to Karim et al. (2010).
Effective at alkaline pH: Nitrites perform best corrosion inhibition in a pH range of 8-10 and should
not be used at pH below 7, which does not fit to the given pH-range in the AADC system of 9-12.
Often borate buffers are used in nitrite formulations to maintain a safe pH. Due to ammonia as cooling
agent there is an ammonium buffer system established in the cooling system, which might not be
compatible with a borate buffer system.
Effective in the absence of oxygen: Sodium nitrite acts as anodic corrosion inhibitor which attacks
directly corroding steel without requiring dissolved oxygen to form a protective oxide film, usually
magnetite (Fe2O4). In this respect sodium nitrite can be used as a corrosion inhibitor in closed systems
as described above.
Experience at
industrial
scale
Experience at
small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35–165°C
Effective at
alkaline pH
(9-12)
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
48
6.3.2.2.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economically feasible. But it has to be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Based on the available information on the substances used within this alternative (see Appendix 2)
sodium nitrite represents the worst case with a harmonized classification as Ox. Sol. 3, Acute Tox. 3
and Aquatic Acute 1. As such, transition from sodium dichromate – which is a non-threshold
carcinogen – to one of these substances would constitute a shift to less hazardous substances.
However, if sodium nitrite would be used as corrosion inhibitor in H&R’s AADC systems there
would be an increased risk of uncontrolled release of ammonia into the environment.
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, the substance failed to prove
sufficient performance already at small scale. Indeed, its capability for the safe and long-term use in
AADC systems is not proven. Therefore, it is questionable if this substance will be subject to further
R&D.
6.3.2.2.4 Conclusion
Sodium nitrite cannot be considered as suitable alternatives as it showed clear technical limitations
already in small scale applications. In summary, the substance cannot be considered suitable for the
given purpose.
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
49
6.3.2.3 Silicates/water glass
6.3.2.3.1 Substance ID and properties
For many years, silicates have been used to inhibit aqueous corrosion, particularly in potable water
systems. Probably due to the complexity of silicate chemistry, their mechanism of inhibition has not
yet been firmly established. They appear to inhibit by an adsorption mechanism. It is thought that
silicates and iron corrosion products interact. However, recent work indicates that this interaction
may not be necessary.
Agrawal and Hindin described in 1993 experiments with several silicate compounds on test vessels
and on commercially available small scale refrigeration systems. Recently, Keller, J. (2014) describes
in the US patent US 2014/0091261A1 the use of water glass in ammonia absorption cooling systems.
The used sodium water glass consists of sodium oxide [Na2O, 6–8% weight by weight (w/w)], silicon
dioxide (SiO2, 25–30% w/w) and water (H2O, 62–69% w/w) (adjusted to 100%). Potassium water
glass was described with a comparable composition. Temperatures from 20–59 °C were tested with
1.5 to 4.5 mass-% of water glass added to the working fluid ('cooling medium'). The result indicates
that the mixture reduces corrosion in AADC systems and are hence described as chromate
substitutions.
Technical feasibility
Corrosion resistance/ Prevention of gas formation: Silicates are considered slow-acting corrosion
inhibitors; in some cases, 2 or 3 weeks may be required to fully establish protection. The protective
layer degrades over time and therefore a constant supply of silicate is said to be necessary (Asrar,
Malik and Ahmed, 1998).
Test in small scale refrigeration systems revealed that sodium silicate generated the same amount of
hydrogen as sodium chromate based systems. Tests were performed for 50 days within a temperature
range of up to 260°C. However, no further information is available if these systems perform in a safe
and reliable manner over long term in an industrial cooling plant.
The patent from Keller (2014) described the use of water glass in ammonia absorption cooling
systems. The used sodium water glass consists of sodium oxide (Na2O, 6–8% w/w), silicon dioxide
(SiO2, 25–30% w/w) and water (H2O, 62–69% w/w) (adjusted to 100%). Potassium water glass was
described with a comparable composition.
In several laboratory tests performed between 1999 and 2010 on six ammonia water based test
machines of the Platen-Munters type with a maximum power of 125 W, it was found that added basic
water glass acts as a corrosion inhibitor. When several test units were opened after far more than 10
years of continuous operation under full load, no traces of corrosion at all were found in the units.
The water glass added acts as a chemical buffer and ensures that the pH of the solvent remains high,
i.e., pH>11, even after many years of operation. Chemical analyses have also revealed that basic
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
50
water glass is not consumed over a period of time in contrast to the traditional Cr(VI) salts in the
solvent but instead is preserved. Water glass also seems to promote the formation of a thin inertizing
protective layer consisting essentially of magnetite crystals (Fe3O4), but also silicon in the interior of
the absorption equipment (Keller, 2014).
Operation in the temperature range of -35° C to 200° C was reported.
Effective in absence of oxygen: As mentioned above oxygen is essential for silicates to properly
function as corrosion inhibitors. As the AADC systems operated by H&R in Hamburg und Salzbergen
are designed as closed systems concentrations of dissolved oxygen are marginal. Oxygen levels of
5.5 ppm, as present in the above mentioned experimental setting of Asrar et al. (1998), do not occur.
Since oxygen – inter alia – is said to be a major factor regarding the corrosion inhibition properties
of sodium silicate for carbon steel the given inhibition efficiency can be expected to further drop
below 62 %.
However, the transformation of silicon into a metal silicate or silicon oxide depends on whether the
surrounding medium is aerated or not (Chen, J-R. et al., 1991).
6.3.2.3.2 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economically feasible. But it has to be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention of
gas
formation
Effective at
Temperature
s 35–165 °C
Effective at
alkaline pH
(9-12)
Effective in
the absence
of oxygen
Silicates/
waterglass
only
Silicates/
waterglass
only
Silicates/
waterglass
only
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
51
Based on the available information on the substances used within this alternative (see Appendix 2)
calcium metasilicate presents the worst case with a classification as Eye Irrit. 2, STOT SE3 and STOT
RE2. As such, transition from sodium dichromate – which is a non-threshold carcinogen – to one of
these substances would constitute a shift to less hazardous substances.
However, if silicates/water glass would be used as corrosion inhibitor in H&R’s AADC systems there
would be an increased risk of uncontrolled release of ammonia into the environment.
6.3.2.3.3 Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. R&D seems to be more advanced than for other
substances, first long-term testing results in ammonia/water based systems were performed. However,
as cooling capacity of industrial cooling plants like the AADC systems operated by H&R in Hamburg
and Salzbergen (Germany) is much higher than the here tested systems (xxxxxxxxxxxxxxxxxxxx),
these promising results cannot easily be adapted to large scale systems. Its capability for the safe and
long-term use in AADC systems has to be proven. Therefore, an extensive development process as
described in Section 5.2 has to be carried out, before the substance could be considered as potential
alternative.
6.3.2.3.4 Conclusion
As of today, the tested corrosion inhibitor systems cannot be considered as suitable alternatives as
there long-term performance in industrial scale has not been proven yet. Further R&D is necessary to
deeper evaluate whether a silicates/water glass based corrosion inhibitor system can be considered as
replacement corrosion inhibitor. To pass a whole development cycle, at least 9-15 years are necessary
if no major drawbacks occur.
6.3.2.4 Zinc containing corrosion inhibitors
6.3.2.4.1 Substance ID and properties
Zinc is used as corrosion inhibitor in various technological fields, including cooling systems. Zinc is
relatively insoluble due to the precipitation of zinc hydroxide whose solubility product (Ksp) is 1.2E-
17. Aqueous solutions with pH > 7.8 contain remarkable concentrations of hydroxide ions which
rapidly increase as the pH rises. Hence, the zinc solubility decreases drastically with increasing pH.
At the cathodic side oxygen is reduced and hydroxide ions are formed. This locally high hydroxide
concentrations cause zinc to precipitate at the cathodic side passivating it with a zinc hydroxide
inhibition film interrupting the redox reaction effectively while minimizing the reaction at the anode
where the metal loss occurs. Therefore, zinc itself belongs to the group of precipitating cathodic
corrosion inhibitors. Mostly common used are zinc sulphate or chloride (Young, T. 1991). Zinc
phosphate is even less soluble [Solubility product (Ksp) = 9.1E-33) than zinc hydroxide. The main
limitation of zinc based corrosion inhibitors are seen in the fact that only local precipitation of zinc
hydroxide at the metal surface to protect is desired, whereas an uncontrolled precipitation would cause
severe problems within the AADC systems.
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
52
Zinc is usually not used alone, but in combination with several other substances as stated in scientific
literature (e.g. Rose et al, 2009; Rajendran et al, 2000, 2003 and 2012; Florence et al, 2005). However,
the usability of zinc mixtures under specific conditions differs according to the synergists’ properties
within the mixed corrosion inhibitor system. These corrosion inhibitors deposit at a pH range of
typically 7-9. Zinc can precipitate as hydroxide, carbonate or phosphate. The chemistry relies on
cathodic corrosion inhibition by zinc, coupled with anodic corrosion inhibition by orthophosphates
(Young, T. 1991; GE Power & Water 2013).
The use of zinc compounds for corrosion inhibition in an ammonia water based system is also
described in a US patent by Agrawal and Hindin (1993). Guerra, M. (2003) describes in an EU patent
application a mixture of KOH, KNO3 and ZnO-3B2O3, as corrosion inhibitor added to the working
fluid ('cooling medium') of a small scale ammonia water based absorption refrigerator. Tests were
performed in commercially available refrigerators for the time of 169 days. However, this patent was
withdrawn in 2009 [Reason according to European Patent Office (EPO) register: examination fee not
paid in time].
6.3.2.4.2 Technical feasibility
Corrosion resistance: In numerous studies corrosion inhibition efficiencies of several zinc based
systems were tested in the laboratory scale as revealed by weight loss experiments. In these
experiments, zinc based systems + additives were tested for their corrosion inhibition effectiveness
on different kinds of steel for varying exposure times. These experiments already showed that
inhibition efficiencies for zinc based systems are pH dependent and are clearly not comparable to
sodium dichromate.
Prevention of gas formation: In the US patent by Agrawal and Hindin (1993) sodium zincate was
tested in commercially available ammonia/water cooling systems for residential use. After 60 days
for the sodium zincate inhibited system hydrogen formation, as a clear sign of corrosion, was
observed at a rate almost 20 times greater than the chromate inhibited cooling system.
In an EU patent (Guerra, 2003), a zinc based system was tested in different small scale ammonia
absorption cooling systems and was considered as promising. After 169 days of testing,
incondensable gas values around 0.1–0.2 ml/hour were observed. However, no long term experience
exists with this zinc based system. Interestingly, the patent was withdrawn in 2009. Furthermore, the
borate compound used within this mixture gives rise to concern, as borates have been identified as
SVHC.
Effective at alkaline pH: Zinc salts in general are described to be effective in the pH range of 6.5 to
8.5. Hence, they are not considered as feasible for the AADC systems operated by H&R in Hamburg
and Salzbergen (Germany) which have a higher alkaline pH range of approx. 9 to 12.
Although the suitability depends on the system of substances used with zinc the formation of zinc
hydroxide is highly problematic in basic pH ranges. Solubility of zinc hydroxide dramatically drops
between pH 7 and 9 (Reichle, McCurdy & Hepler, 1975). Occurring deposits of precipitated zinc
hydroxide may cause complications within the cooling system.
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
53
Under the given circumstances in the AADC systems operated by Hamburg and Salzbergen
(Germany), especially with the given alkaline pH between 9 and 12, it can be expected that zinc will
precipitate as hydroxide within the system. This precipitation is different from the desired
precipitation process at the cathodic side, because immediate local precipitation of zinc hydroxide at
the place where the substance is added can be assumed. The hydroxide would potentially circulate as
solid matter within the closed cooling system.
Based on scientific literature and patents, it can be concluded that none of the zinc containing mixtures
is a suitable alternative to sodium chromate as corrosion inhibitor.
6.3.2.4.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economically feasible. But it must be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Based on the available information on the substances used within this alternative (see Appendix 2),
boron trioxide (B2O3) constitues the worst case with a classification as Acute Tox. 4, Skin Corr. 1B,
Aquatic Chronic 1 and Aquatic Acute 1. As such, transition from sodium dichromate – which is a
non-threshold carcinogen – to one of these substances would constitute a shift to less hazardous
substances.
However, if zinc containing corrosion inhibitors would be used in H&R’s AADC systems there would
be an increased risk of uncontrolled release of ammonia into the environment.
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35–165 °C
Effective at
alkaline pH
(9-12)
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
54
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, its capability for the safe and long-
term use in AADC systems is not yet proven. Therefore, an extensive development process as
described in Section 5.2 must be carried out, before the substance could be considered as potential
alternative.
6.3.2.4.4 Conclusion
In one patent (Guerra, M., 2003), a zinc containing mixture showed promising results in small scale
refrigeration systems. However, this patent was withdrawn in 2009 (Reason according to EPO
register: examination fee not paid in time). In summary, the tested zinc containing corrosion inhibitor
systems cannot be considered as suitable alternatives as they showed technical limitations already at
laboratory and in small scale applications. Furthermore, its capability for the safe and long-term use
in AADC systems is not yet proven. In summary, the substance cannot be considered suitable for the
given purpose.
6.3.2.5 Strong alkaline solutions
6.3.2.5.1 Substance ID and Properties
Several patents describe the use of alkaline solutions for corrosion inhibition in ammonia water based
systems. In a US patent from Phillips et al. (1996), a method of inhibiting corrosion and the formation
of hydrogen is described in ammonia water based absorption cooling, air conditioning or heat pump
system by maintaining the hydroxide ion concentration of the aqueous ammonia working fluid, within
a selected range under anaerobic conditions at temperatures up to ca. 218 °C (425° F). Erickson D.C.
(1999) describes a method of corrosion inhibition in an aqueous ammonia absorption refrigeration
apparatus based on an alkali metal base. A process for controlling corrosion and hydrogen generation
in the aqueous ammonia absorption cycle apparatus is also disclosed. Variations have been tested,
including NaOH, LiOH, KOH, RbOH, CsOH and GeO2 as additive. Guerra, M. (2003) describes in
an EU patent application a mixture of KOH, KNO3 and ZnO-3B2O3, as corrosion inhibitor added to
the working fluid ('cooling medium') of a small scale ammonia water based absorption refrigerator.
Tests were performed in commercially available refrigerators for the time of 169 days. It is of note
that the aforementioned patents are expired meanwhile, as the maintenance fees were not paid.
6.3.2.5.2 Technical feasibility
Corrosion resistance/ Prevention of gas formation: In most patents an experimental corrosion test
apparatus was used instead of small scale systems that are used in real life. The test apparatus was
designed to operate at conditions simulating those in the hottest part of the generator, and has boiling
surfaces, peak temperatures that accelerate the corrosion reactions, and a recirculating ammonia water
based working fluid ('cooling medium'). The test was performed for approximately 1 year. The
corrosion inhibition capabilities have been described as appropriate. Examples of strong bases
suitable for use include, alkali metal bases, such as sodium hydroxide, potassium hydroxide, lithium
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
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hydroxide and caesium hydroxide. Preferably, the strong base is lithium hydroxide, or sodium
hydroxide.
The EU patent (Guerra, 2003) reported the testing of several corrosion inhibitors also those described
in the aforesaid previous patents. Guerra et al. tested these on real machines, with the discovery that
they are much less effective than the corrosion inhibitors claimed as follows: a zinc based system
with KOH as additive in different small scale ammonia absorption cooling systems was considered
as promising. After 169 days of testing, incondensable gas values around 0.1–0.2 ml/hour were
observed. However, no long term experience exists with these system. In contrast, when known
refrigerator units were tested with KOH only, gas formation was remarkably high and the
performance clearly insufficient. Interestingly, the patent was withdrawn in 2009.
Effective at 35–165 °C: The literature indicates that the alternative is working at high temperatures
(<218° C). Only Guerra tested in real small scale systems, demonstrate that alkaline systems alone
did not work properly, while performance could be improved when using an alkaline zinc borate
based systems. No experience exists on the large temperature differences as present in AADC
systems.
Effective at alkaline pH: The literature indicates that the alternative is appropriate in the given pH
range.
6.3.2.5.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economical feasible. But it has to be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
6.3.2.5.4 Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35–165 °C
Effective at
alkaline pH
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
56
Based on the available information on the substances used within this alternative (see Appendix 2),
KOH constitute the worst case with a classification as STOT SE3, Skin Irrit. 2 and Eye Irrit 2. As
such, transition from sodium dichromate – which is a non-threshold carcinogen – to one of these
substances would constitute a shift to less hazardous substances.
However, if strong alkaline solutions would be used as corrosion inhibitor in H&R’s AADC systems
there would be an increased risk of uncontrolled release of ammonia into the environment.
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, its capability for the safe and long-
term use in AADC systems is not proven. Therefore, an extensive development process as described
in Section 5.2 must be carried out, before the substance could be considered as potential alternative.
6.3.2.5.5 Conclusion
Test performed with alkaline corrosion inhibitor systems in general were clearly found to be
insufficient. In one patent (Guerra, M., 2003), an alkali based zinc borate containing mixture showed
promising results in small scale refrigeration systems. However, this patent was withdrawn in 2009
(Reason according to EPO register: examination fee not paid in time). In summary, the tested
corrosion inhibitor systems cannot be considered as suitable alternatives as they showed technical
limitations already at laboratory and in small scale applications. Furthermore, its capability for the
safe and long-term use in AADC systems is not yet proven. In summary, the substance cannot be
considered suitable for the given purpose.
6.3.2.6 Phosphates and phosphonate compounds
6.3.2.6.1 Substance ID and properties
For corrosion inhibition in cooling systems, several phosphates based corrosion inhibitor systems are
discussed in scientific literature. Trisodium phosphate (Na3PO4) are used in industrial cooling water
systems as antiscalants, which can positively influence the corrosion rate. The primary reactant for
carbon steel corrosion inhibition is oxygen, due to the formation of a thin oxygen film. The dissolved
oxygen produces a thin film of γ-Fe2O3, where the phosphate ions fill in the voids and accelerate film
growth. These plugs prevent further diffusion of Fe2+ ions from the metal surface. If these complexes
are hydrolysed this leads to local attacks by the production of acid domains.
Phillips et al. (1996) describe in a patent specification phosphate as possible “unfavourable” corrosion
inhibitors for ammonia water based cooling systems. Hindin et al. (1992) describe in a patent
specification different substances, including sodium phosphate (Na3PO4) as possible corrosion
inhibitors for ammonia water based systems. Hindin concludes that phosphates lead to a worse
Inhibition Efficiency (IE) compared to other substances tested.
In combination with zinc, a NaZnPO4 film can be built whereas the Zn2+ ion binds to any two adjacent
oxygen atoms. Inhibition may be caused by the stabilization of the surface film in form of an iron
complex (NaFePO4) which is more stable than a zinc film (NaZnPO4). The iron complex provides
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
57
anodic corrosion protection whereas formation of insulated film of zinc hydroxide [Zn(OH)2] at
higher pH levels provides cathodic corrosion protection.
Phosphonates and phosphonic acids are organophosphorus compounds containing carbon-bonded
PO(OH)2 or PO(OR)2 groups (where R = alkyl, aryl). Phosphonates as organic phosphorous
compounds can be distinguished from inorganic polyphosphates in that all phosphonates contain
direct carbon-phosphorous bonds. Phosphonates are used in cooling water treatment to control
calcium carbonate scale. Additionally, they possess corrosion inhibition properties. Phosphonates
belong to the precipitating corrosion inhibitors which are protecting both anodic and cathodic sites
by the precipitation of calcium and iron salts forming protective films. For carbon steel protection,
Hydroxy Phosphonic Acid (HPA) was specifically designed as corrosion inhibitor. When used alone,
HPA crucially needs calcium in water for effective protection of carbon steel. A general problem with
phosphonates is their decomposition over time to orthophosphates which are poor corrosion
inhibitors. This reversion is increased by high and low pH, high temperature and the presence of
oxidisers like chlorine or bromine. Studies indicate that phosphonates are effective corrosion
inhibitors for carbon steel when combined with zinc (NISCAIR, GE Power & Water 2013, Rao
B.V.A., et al 2013).
6.3.2.6.2 Technical feasibility
Corrosion resistance: Phosphate stabilized inhibition systems are able to prevent corrosion but to a
far less extent as chromate/zinc based systems. Under operating conditions as described for
ammonia/water systems, this replacement technology is clearly insufficient.
Prevention of gas formation: The passivating process induced by phosphate ions is based on the
production of a protective Fe2O3 layer. During this process hydrogen is generated.
Effective at temperatures 35–165 °C: Tests with phosphates and orthophosphates in carbon steel at
temperatures of 20-80 °C showed and insufficient performance. The solubility of the passivating layer
increased within the tested temperature range (Kilinççeker et al, 1999; Pryor and Cohen, 2001). As
H&R’s cooling systems operate at temperatures up to 165 °C, phosphates do not constitute a suitable
alternative.
Effective at alkaline pH: Phosphate is used primarily in zinc based cooling water corrosion protection
systems that will be operated at a pH of 8.5 or less. The inclusion of phosphate, normally as
orthophosphate, to zinc containing corrosion inhibitory solutions at lower pH result in the formation
of mixed zinc hydroxide/phosphate protective films at the cathode. At relatively high pH tested (pH
7.2 and pH 12.3) it could be shown that phosphate ions in combination with sulphate ions have an
increased capability of corrosion inhibition than phosphate alone and give an overall corrosion
protection (Kilinççeker et al, 1999; Raheem, 2011; Armstrong et al, 1994).
Effective in absence of oxygen: It is assumed that oxygen dissolved in solution is a main reason for
generating a passivation layer due to a heterogeneous reaction of phosphates with surface iron atoms
forming Fe2O3. Sodium phosphate is described as corrosion inhibitor that essentially requires oxygen
for its passivating activity (Pryor and Cohen, 2001).
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
58
In summary, any of the tested phosphate compounds showed severe limitations in terms of the key
requirements as concluded in the table below. Most importantly, they are not able to provide the same
level of corrosion resistance as sodium dichromate and are therefore no alternative in AADC systems.
6.3.2.6.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economically feasible. But it has to be taken into account that adverse interactions between the
current and the new (substitute) inhibition system may occur. So on one hand there are costs linked
to the thorough replacement of the old inhibition system and on the other hand additional costs can
occur in case of unexpected interactions that impair the functionality of the inhibition system, as
unexpected corrosion leads to downtime of the AADC system and thus the wax and base oil
production. In any case, severe business impacts can be expected if the substitute inhibiton system
fails and a switch-back to sodium dichromate as corrosion inhibitor is not possible. To avoid this
scenario, the only solution is to replace the solution cycle equipment hardware to avoid any residual
“old” corrosion inhibitor, which of course comes with additional costs that need to be taken into
account.
6.3.2.6.4 Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Based on the available information on the substances used within this alternative, trisodium phosphate
(see Appendix 2) would represent the worst case with a classification as Skin Irrit. 1, Eye Irrit. 1,
STOT SE3, Skin Corr. 1C. As such, transition from sodium dichromate – which is a non-threshold
carcinogen – to one of these substances would constitute a shift to less hazardous substances.
However, if phosphates and phosphonate compounds would be used as corrosion inhibitor in H&R’s
AADC systems there would be an increased risk of uncontrolled release of ammonia into the
environment.
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, its capability for the safe and long-
term use in AADC systems is not yet proven. Therefore, an extensive development process as
described in Section 5.2 has to be carried out, before the substance could be considered as potential
alternative.
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35–165 °C
Effective at
alkaline pH
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
59
6.3.2.6.5 Conclusion
In summary, any of the tested phosphate compounds showed severe limitations in terms of the key
requirements already at laboratory scale. They are not able to provide the same level of corrosion
resistance as sodium dichromate and are therefore no alternative in AADC systems.
6.3.2.7 Rare Earth Metal Salts
6.3.2.7.1 Substance ID and Properties
Rare Earth Metal Salts (REMSs) are described in the literature and patent specifications as suitable
corrosion inhibitor for substrates such as aluminium alloys, steel and zinc.
In several publications and a US patent Mansfeld, F. B. (2003) described the use of cerium nitrate
[Ce(NO3)3] which is add to the ammonia water based working fluid in a heat pump to inhibit corrosion
of the steel surfaces. Concentrations REMS is reported to be between 10 mM to 350 mM. Cerium is
expected to act by steel surface passivation due to oxide/hydroxide layer formation.
Carbon steel can be coated with cerium, assisted by hydrogen peroxide (H2O2) resulting in a layer
that provides corrosion inhibition. Nevertheless, to use hydrogen peroxide in the closed AADC
systems operated by H&R in Hamburg and Salzbergen would lead to undesired gas formation.
6.3.2.7.2 Technical feasibility
In the existing studies and patents, REMSs were tested on steel plates in test vessels for up to 48 h.
None of these tests were performed on real scale systems. Importantly, the patent where these
interventions are described expired due to failure of maintenance fee 5 years after assignment of the
patent. In summary, no reliable studies or experiences exist that REMSs are a potential alternative as
corrosion inhibitor in AADC systems.
6.3.2.7.3 Economic feasibility
Based on the literature research and consultations, there is no indication that the discussed alternative
is not economical feasible. Nevertheless, prices for pure cerium as rare earth metal are relatively high.
But it has to be taken into account that adverse interactions between the current and the new
(substitute) inhibition system may occur. So on one hand there are costs linked to the thorough
replacement of the old inhibition system and on the other hand additional costs can occur in case of
unexpected interactions that impair the functionality of the inhibition system, as unexpected corrosion
leads to downtime of the AADC system and thus the wax and base oil production. In any case, severe
business impacts can be expected if the substitute inhibiton system fails and a switch-back to sodium
Experience
at industrial
scale
Experience
at small scale
Corrosion
resistance
Prevention
of gas
formation
Effective at
Temperatures
35–165°C
Effective at
alkaline pH
Effective in
the absence
of oxygen
ANALYSIS OF ALTERNATIVES
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60
dichromate as corrosion inhibitor is not possible. To avoid this scenario, the only solution is to replace
the solution cycle equipment hardware to avoid any residual “old” corrosion inhibitor, which of
course comes with additional costs that need to be taken into account.
6.3.2.7.4 Reduction of overall risk
As the alternative is not technically feasible, only classification and labelling information of
substances and products reported during the consultation were reviewed for comparison of the hazard
profile.
Based on the available information on the substances used within this alternative (see Appendix 2)
cerium trinitrate represents the worst case with a classification as STOT SE3, Skin Irrit. 2 and Eye
Irrit 2. As such, transition from sodium dichromate – which is a non-threshold carcinogen – to one of
these substances would constitute a shift to less hazardous substances.
However, if rare earth metal salts would be used as corrosion inhibitor in H&R’s AADC systems
there would be an increased risk of uncontrolled release of ammonia into the environment.
Availability
Based on the literature research and consultations, there is no indication that the discussed alternative
is not commercially available in appropriate amounts. However, its capability for the safe and long-
term use in AADC systems is not proven. So far, not even tests in small scale were performed.
Therefore, an extensive development process as described in Section 5.2 has to be carried out, before
these substances could be considered as potential alternatives.
6.3.2.7.5 Conclusion
The tested corrosion inhibitor systems cannot be considered as suitable alternatives as they showed
technical limitations already at laboratory and in small scale applications. Furthermore, its capability
for the safe and long-term use in AADC systems is not yet proven. In summary, the substances cannot
be considered suitable for the given purpose.
ANALYSIS OF ALTERNATIVES
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61
7. OVERALL CONCLUSION ON SUITABILITY AND AVAILABILITY OF
CORROSION INHIBITOR ALTERNATIVES
H&R uses sodium dichromate as a corrosion inhibitor in two AADC systems operated at their sites
in Hamburg and Salzbergen (Germany). For many decades, AADC systems made of carbon steel
have constituted a safe and reliable cooling technology for miscellaneous industry sectors. This was
ensured by using sodium dichromate as a corrosion inhibitor, enabling high performance under
specific process conditions. For the purpose of this AoA, different chemical and technical alternatives
have been evaluated.
Three different alternatives were discussed:
1. The replacement (change) of the existing AADC system by switching to VCC as an alternative
cooling technology, described in Section 6.1. Even though technically feasible, the switch
would be accompanied with severe economic impacts. A switch to VCC would in H&R’s case
amount to net economic impacts of EUR 40 million (considering investment in a new cooling
system, value added forgone due to downtime and additional operational costs), which in total
points against this alternative today. More detailed calculations are provided in the SEA
document.
2. As described in Section 6.2, the replacement of corrosion prone parts, mainly carbon steel
parts by more resistant parts, e.g. stainless steel or permanently coated metal parts is another
potential alternative. From a technical and economic point of view a replacement of corrosion
prone parts cannot be considered as suitable. As of today, no standard or best-practice solution
is applicable for H&R’s sites in Hamburg and Salzbergen (Germany). It was highlighted that
stainless steel systems of a similar size to H&R’s systems are currently not operated and no
reliable conclusion about the presence or absence of corrosion inhibitors in such systems can
be drawn. It was also clearly outlined, that stainless steel is subject to corrosion in ammonia
water based systems, especially at higher temperatures. It was also recommended by
specialists that in this case sodium dichromate should be used as only long-term proven
corrosion inhibitor. Therefore, from a technical perspective, the exchange of corrosion prone
parts cannot be considered as a suitable alternative.
3. The substitution of sodium dichromate by another corrosion inhibitor would be the easiest and
cheapest alternative. It is described in Section 6.3. Extensive efforts were made during the last
years to identify possible alternatives for corrosion inhibitors in AADC systems. Over the
course of these efforts, scientific literature was screened and evaluated comprehensively.
Experts from other companies dealing with similar cooling systems were approached.
Moreover, several other international research institutes were contacted to discuss and
evaluate the state of the art for corrosion inhibition in this type cooling systems.
The analysis revealed that there is limited available experience on replacement substances for
large scale industrial cooling systems. As of today, no drop-in alternative to sodium
dichromate for the use as a corrosion inhibitor in AADC systems is available.
ANALYSIS OF ALTERNATIVES
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62
AADC systems made of carbon steel have been used as a safe and reliable cooling technology
for decades. Using sodium dichromate as a corrosion inhibitor ensures a long-lasting life time
of the cooling plants (up to 50 years). Indeed, scientific and technical research was performed
over decades suggesting a variety of replacement corrosion inhibitors. Nevertheless, all
alternatives discussed in scientific and technical literature were not tested under realistic
conditions in large-scale systems for a realistic time span. Therefore, no replacement
substance could be identified. For the development and industrial upscaling of a possible
alternative for sodium dichromate as a corrosion inhibitor in AADC systems made of carbon
steel several phases, bringing an alternative step by step to final application would be
necessary. The integrity and reliability of the system must be ensured over the expected
lifetime of the facility. Unexpected corrosion would lead to system downtime associated by
immense costs and a reduced environmental and occupational safety. In this context, it would
be unjustifiable to simply start a substitution in form of a field trial without having enough
scientific and empirical data about the safe use of such alternatives.
As clearly outlined in Section 5.2, passing the whole development and implementation process plus
the required monitoring will easily take 20 years. Taking into account the limited worker exposure to
sodium dichromate in combination with extremely high occupational safety measures (see CSR), the
resulting considerable low health impacts (under existing conditions there is no concern and
negligible risk for workers and the environment) and the comparably high economic impacts (see
SEA), the most reasonable option is to run the AADC systems operated by H&R until the end of their
expected lifetime (20 and 35 years from now). Therefore, H&R applies for a review period of 20
years for the use of sodium dichromate.
ANALYSIS OF ALTERNATIVES
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(2009): Corrosion Inhibition by Monosodium Glutamate-Zn2+ System. ZAŠTITA
MATERIJALA 50: p. 187-192
41. Mansfeld, F. B., Zhaoli, S. (2003): US Patent 6,632,294 B2
42. Moser, H., Zotter, G., Kotenko, O., Rieberer, R., (2011): The Formation of Non-Condensable
Gases in Ammonia/Water Absorption Heat Pumps made of Stainless Steel - Literature Review
and Experimental Investigation, Proceedings of the 4th IIR International Conference on
Ammonia Refrigeration Technology, Ohrid, April 14-16, 2011
43. NISCAIR online Periodicals Repository (2007): Corrosion Inhibition by Sodium Potassium
Tartrate-Zn2+ system for Carbon Steel in Rainwater Collected from Roof Top
(http://nopr.niscair.res.in/handle/123456789/1136 [last accessed: 20.01.2016])
44. Palou, R. M., Olivares-Xomelt, O., Likhanova, N.V. (2014): Environmentally Friendly
Corrosion Inhibitors. http://dx.doi.org/10.5772/57252; INTECH (Chapter 19)
45. Patent (1999): Absorption Refrigeration System Working Fluid with Corrosion Inhibitor and
Method of Manufacture CA 2174184 C; 1999
46. Petersen, P.R., Lordo, S. A., McAteer, G. R. (2014): Choosing a Neutralising Amine Corrosion
Inhibitor. Digital Refining Processing, Operations & Maintenance
(http://www.digitalrefining.com/article/1000509,Choosing_a_neutralising_amine_corrosion_inh
ibitor.html#.VUEGyE0cRmM [last accessed: 20.01.2016])
47. Phillips, B.A. et al. (1996): US Patent No. 5,811,026
48. Pryor, M.J., Cohen, M. (2001): The Mechanism of the Inhibition of the Corrosion of Iron by
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49. Raheem, D. (2011): Effect of Mixed Corrosion Inhibitors in Cooling Water System. Al-
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50. Rajendran, S., Thangavelu, C., Annamalai, G. (2012): Inhibition of Corrosion of Aluminium in
Alkaline Medium by Succinic Acid in Conjunction with Zinc Sulphate and Diethylene Triamine
Penta (Methylene Phosphonic Acid). Journal of Chemical and Pharmaceutical Research; 4(11):
p. 4836-4844
51. Rajendran, S., Reenkala, S. M., Ramaraj, R. (2002): Synergistic Corrosion Inhibition by the
Sodium Dodecylsulphate–Zn2+ System. Corrosion Science, Vol. 44 (10): p. 2243–2252
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Water System. J. Electrochem. Soc. Vol. 139 (11): p. 3167-3173
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Inhibitors in Water and in Aqueous Solutions. Journal of Applied Chemistry, 2(3): p. 150-160
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ANALYSIS OF ALTERNATIVES
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APPENDICES
Appendix 1 - Category 2 alternatives
Alternative Substance properties Feasibility
Amines
Amine based corrosion inhibitors are
commonly used in industrial
lubricants, greases and rust-
preventive fluids. Typical amine
based corrosion inhibitors are:
ammonia, dimethylethanolamine,
ethylenediamine,
methoxypropylamine,
monoethanolamine, morpholine,
picolines and amines. They are used
as corrosion inhibitors in the oil and
gas industry, where they support the
inhibition of corrosion induced by
hydrochloride in connection with
water. For that purpose, ammonia has
been widely used for decades.
Amines are often used in de-aerated
NaCl containing aqueous solutions.
Studies describe amine based
corrosion inhibitors as active due to
physical adsorption on the metal
surface (Buchweishaija, 2002).
Hydrazine (N2H4) is described as
possible corrosion inhibitor which
does not act as an electrochemical
type corrosion inhibitor. Instead it
decreases corrosion potential by the
reduction of oxygen present in the
fluid, which leads to the formation of
water and nitrogen. Usually hydrazine
is used as an additive to boiler feed
water (Petersen et al., 2014).
Formulations based on dilute aqueous
solutions of N,N′-
Dimethylethanolamine (DMEA) are
used to protect reinforcement steel
bars (‘rebar’) in concrete from
corrosion. DMEA is a widely
common corrosion inhibitor often
used to protect iron in concrete and in
alkaline and chlorine containing
solutions. Studies described DMEA
Corrosion resistance is described to be
very good and IE accordingly high.
Oxygen is generally removed by
reductive corrosion inhibitors such as
amines and hydrazines according to
the following equation: O2 + N2H4
→ 2 H2O + N2, and therefore the
corrosion inhibition mechanism of
hydrazines bases on the removal of
oxygen under the release of gaseous
nitrogen.
DMEA as corrosion inhibitor is
studied and reported in scientific
literature. The assessed reports
describe DMEA as corrosion
inhibitory active in the presence of
NaCl and at acidic pH.
Studies evaluated describe DMEA as
active at temperatures of around
25 °C.
Hydrazine has been identified as
SVHC for its cancerogenic
properties. Hydrazine is classified as
Flam. Liq. 3 and its usability within
the H&R’s facilities would lead to
additional chemical hazards.
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems may be fulfilled by
amines. Nevertheless, the inhibition
mechanism depends on the formation of
nitrogen gas. Additionally, its capability
for the safe and long-term use in AADC
systems is not yet proven. Therefore,
these substances are not regarded as an
alternative to sodium dichromate.
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Alternative Substance properties Feasibility
alone as unsuitable corrosion
inhibitor for carbon steel, but as
acceptable in combination with
caprylic acid. The mechanism of
organic corrosion inhibitors is not
clear but it is assumed that DMEA
displaces chloride ions and forms a
passivating film on the metal surface.
Tartrate
compounds
According to literature, tartrate
compounds are often used as
synergist in combination with other
substances for corrosion inhibition in
liquid media. Corrosion inhibition
effects of sodium potassium tartrate
and Zn2+ mixtures for example could
be shown for carbon steel immersed
in rain water.
The substance is known as corrosion
inhibitor for aluminium and carbon
steel alloys. Here it provides good
inhibition efficiency as anodic
corrosion inhibitor and in
combination with zinc ions mixed
corrosion inhibitor properties. Also
sodium potassium tartrate in
combination with zinc show
synergistic effects in controlling the
corrosion of carbon steel. Studies
showed such effects for carbon steel
immersed in rain water collected from
roof top and stored in concrete tanks.
91 % corrosion IE was measured for a
formulation consisting of 50 ppm
sodium potassium tartrate and 25 ppm
zinc (NISCAIR).
According to the CRC Handbook of
Chemistry and Physics (84th edition,
Boca Raton, FL: CRC Press Inc.,
2003-2004, p. 4-85) the melting point
of potassium sodium tartrate is
130 °C and the decomposition
temperature 220 °C. Due to the low
boiling and decomposition point it
can be assumed that the substance
may lead to gas formation in parts of
the cooling unit with higher
temperature.
So far no scientific information about
the temperature range for proper
functioning of the substance could be
identified. Due to the relatively low
boiling (ca. 130 °C) and
decomposition (ca. 220°C) point
tartrate is considered as not suitable
at higher temperatures.
The corrosion inhibitor system acts as
a mixed type corrosion inhibitor and
could be shown to be effective in the
pH range 6-8. Electrochemical
impedance studies indicated the
formation of a dense protective film
which is only protective in the
presence of optimum amounts of the
above mentioned compounds at a
given pH value (Rao et al., 2013).
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems may be fulfilled by
tartrate compounds according to the
literature. However, its capability for the
safe and long-term use in AADC systems
is not yet proven. Therefore, a detailed
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Alternative Substance properties Feasibility
R&D process including long-term testing
on pilot scale and further industrial
upscaling have to be performed before the
final performance of tartrate compounds
can be assessed ultimately.
Benzoate
Sodium benzoate (NaC7H6O2) is used
as corrosion inhibitor for different
uses including carbon steel. The main
factors affecting corrosion inhibition
of iron in sodium benzoate solutions
are the concentration of benzoate, the
pH of the solution and the dissolved
oxygen concentration (Davieset al.,
1973).
Sodium benzoate is described to show
corrosion inhibition potential for
carbon steel. It has been shown to be
an effective inhibitor of the corrosion
of mild steel in distilled water, in
moderately hard mains-water and very
dilute (e.g. 0.03 %) sodium chloride
solutions. Sodium benzoate is
described as less efficient than sodium
chromate but it is, however, named
‘safe inhibitor’ since it does not lead
to intense localized corrosion when
the concentration is just below the
minimum for protection. Furthermore,
the efficiency is higher at clean
surfaces and is decreased with time in
stationary and flow conditions
(Hassan et al., 2011).
Sodium benzoate corrosion inhibition
is reported as effective at
temperatures of 30 – 50 °C.
(Wormwell and Mercer 1952, Ivušić
et al., 2014). Further information
about higher temperatures could not
be identified
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems may be fulfilled by
sodium benzoate according to the
literature. However, the corrosion
inhibition capacity is described to
decrease with increasing velocity. Due to
the high velocity of the AADC system
this alternative is considered to be not
appropriate. Furthermore, its capability
for the safe and long-term use in AADC
systems is not yet proven. Therefore, a
detailed R&D process including long-
term testing on a pilot scale and further
industrial upscaling have to be performed
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Alternative Substance properties Feasibility
before the final performance of benzoates
can be assessed ultimately.
Glutamate
Mono Sodium Glutamate (MSG)
(NaC5H9NO4) in combination with
zinc show synergistic effects as a
mixed corrosion inhibitor system
used for carbon steel as underpinned
by polarisation studies. AC
impedance spectra reveal a protective
film formed on the metal surface. FT-
IR spectra indicate that the protective
film consists of Fe2+-MSG complex
and Zn(OH)2 (Leema Rose et al.,
2009).
A formulation of 100 ppm MSG and
50 ppm Zn2+ shows an IE of 86 %
which increases with pH. Studies
reveal that for this mixture the
acceptable pH is around the neutral
point, which in turn is below the pH
of AADC systems (Leema Rose et
al., 2009).
Furthermore, increasing (alkaline) pH
holds negative influence on the
inhibition efficiency of MSG-Zn²+
systems (Leema Rose et al., 2009).
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems are not fulfilled by
glutamate. Furthermore, its capability for
the safe and long-term use in AADC
systems is not determined. Therefore, the
substance is not considered as an
alternative to sodium dichromate.
Succinic
acid
Succinic Acid (SA) is a dicarboxylic
acid, which is most commonly known
for its role in the citric cycle of
intermediary metabolism. Besides
various applications e.g. in food,
pharmaceuticals, agriculture and
industry SA is known to possess anti-
corrosive properties. Therefore it is
used e.g. for coatings and in water
cooling systems (Chemicalland 21,
2015). The corrosion inhibitory effect
of organic substances like SA is
explained by adsorption of the agent
to the metal surface resulting in a
protective film that prevents
corrosion by separating the metal
surface and the electrolyte (Dariva
and Galio 2014).
In this context SA is often used in
combination with other agents like
zinc or is part of a whole series of
ingredients in mixtures of anti-
corrosive products. Nevertheless,
Studies revealed the role of SA as
anodic-type corrosion inhibitor on low
carbon steel in an aerated, non-stirred
environment, with acidic pH (1.0 M
HCl) in the range of 2 - 8 at 25 °C.
Negative effects of increasing
temperature on the corrosion
inhibition properties of SA concerning
carbon steel were observed. A shift in
the corrosion inhibitory effect might
be a severe disadvantage for an
application of SA in the given
temperature range of the production
process (Deyab and Abd El-Rehim
2013).
There is evidence that in combination
with carbon steel, the performance of
SA as corrosion inhibitor is a
function of the agent concentration.
An optimum was detected at a
concentration of 50 ppm SA at pH 3.
This indicates that the pH in the
AADC system might be too high to
ANALYSIS OF ALTERNATIVES
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Alternative Substance properties Feasibility
there is evidence on the use of mere
SA as an anti-corrosive substance.
guarantee proper corrosion inhibition
by SA.
In contrast to the above mentioned the
literature review yielded results
indicating corrosion inhibition of SA
at pH 12 but for aluminium as the
substrate to be protected and only for
SA in combination with other
chemicals (Deyab and Abd El-
Rehim, 2013, Rajendran et al., 2012).
Based on the available information on
the substances used within this
alternative, SA would be the worst
case with a classification as Muta. 1B
and Carc. 1B. As such, transition
from sodium dichromate – which is a
non-threshold carcinogen – to one of
these substances would not constitute
a shift to less hazardous substances
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems is not fulfilled by
SA. Especially the pH range reported in
the literature is not appropriate for the
given use in AADC systems.
Additionally, its capability for the safe
and long-term use in AADC systems is
not yet proven. Therefore, the substance
is not considered as an alternative to
sodium dichromate.
Organic
inhibitors
The field of organic corrosion
inhibitors is very heterogeneous. The
mode of action is based upon
cathodic and anodic inhibition
schemes or a coupling of both. But in
general, organic inhibitors establish
protective layers on the surface of the
substrate (Dariva and Galio, 2014).
Due to the importance of this
corrosion inhibitor class - literally
often claimed as ‘environmental
friendly’ - some substances which are
not separately discussed within this
AoA are summarized here. Various
organic compounds are used as
Sekine at al. (1992) indicate the use of
several organic polymers, such as
polymaleic acid derivative (PMAD),
polyacrylic acid derivative (PAAD)
or polyacrylic acid (PAA), for
corrosion inhibition in cooling water
systems. Thereby, only anionic
polymers are considered to be
effective due to the adsorption to the
metal surface and subsequently the
formation of a protective layer.
According to Samide et al. (2005) N-
cyclohexyl-benzothiazolesulfenamide
(NCBSA) is effective in inhibiting
corrosion of carbon steel in ammonia
solutions at room temperature by
ANALYSIS OF ALTERNATIVES
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Alternative Substance properties Feasibility
corrosion inhibitors. Some of them
are already discussed in other
sections. Organic inhibitors usually
contain heteroatoms, often nitrogen
groups, such as amines or sulphur or
hydroxyl groups often as surfactants
with dual functionality. Contained
hydrophilic group can adsorb on the
metal surface, and an opposing
hydrophobic group prevents further
wetting of the metal. Size,
orientation, shape, and electrical
charge distribution of the molecules
are important factors for the corrosion
inhibition efficiency. Glycine
derivatives and aliphatic sulfonates
are examples of compounds which
can function in this way (Dariva and
Galio, 2014).
All-organic corrosion inhibitory
programs are frequently used in
systems without pH control and they
rely on systems that have a tendency
to form scale as opposed to corrosion.
All-organic programs are normally
not used in aggressive waters. Some
companies offer corrosion inhibitors
under various trade names, as for
example HALOX® organic corrosion
inhibitors which are described to be
effective against flash rusting and in-
can corrosion prevention. The
corrosion inhibitors are described to
be suitable for high gloss, thin film,
and clear coat applications (ICL,
2015; Palou et al., 2014; Rani and
Basu, 2012).
adsorption of the compound on the
metal surface.
Glycine derivatives and aliphatic
sulfonates, as a group of organic
corrosion inhibitors, can form thick,
oily surface films, which may
severely retard heat transfer. This
may lead to an increased demand in
primary energy. In general, organic
inhibitors are described as not
suitable for higher temperatures.
Organic inhibitors are described to be
suitable in alkaline pH. However,
available scientific literature rather
refers to corrosion processes in acidic
media and data is therefore less
assignable to AADC systems
operating in the range of pH 9 to 12.
In summary, the key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems may be fulfilled by
organic inhibitors. However, its capability
for the safe and long-term use in AADC
systems is not yet proven. Therefore, a
detailed R&D process including long-
term testing on a pilot scale and further
industrial upscaling have to be performed
before the final performance of organic
inhibitors can be assessed ultimately.
Azole and
azoline
Imidazole is an aromatic heterocycle
which is known as a component of
several biochemical molecules and for
its anti-fungal properties. Imidazole
derivatives are described as
adsorption-type, organic inhibitor that
forms a hydrophobic film on metal
surfaces and hinders the corrosion
reaction by this barrier. Imidazole-
There is evidence that imidazoline
provides an inhibition efficiency of
maximum 90 % at a temperature of
about 150°C at 207 bar (Chen,
2000). This inhibition performance is
considered insufficient for the
application of imidazoline as
corrosion inhibitor in AADC systems
operated by H&R.
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Alternative Substance properties Feasibility
based corrosion inhibitors, e.g. 1-
methyl 2-mercapto imidazole are
mainly used in crude oil and gas
industry to protect work effectively
against CO2 corrosion (Ahmad Jaal et
al., 2014).
A number of studies discussing
imidazoline derivatives show that
high rates of shear stress, turbulent
flow conditions and bubble impact
significantly decrease the corrosion
inhibition performance of these
substances. Under these conditions
the inhibitor film is destroyed or
removed from the surface (Chen,
2000; Hong et al., 2002; Chen and
Jepson, 1999).
In summary, some key requirements for
corrosion inhibitors in terms of suitability
to alkaline pH, closed circuits, hot and
chilled water systems may be fulfilled for
some azoles like imidazole. Nevertheless,
literature results indicate that this
corrosion inhibitor might not be effective
in the given temperature range and at the
given turbidity. Additionally, the
capability for the safe and long-term use
in AADC systems is not yet proven.
Therefore, these substances are not
considered as an alternative to sodium
dichromate.
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Appendix 2 – Information on chemical substances assessed in Section 6.3
Appendix 2.1: Ammonium molybdate
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Ammonium molybdate
(VI) tetrahydrate
Physical state at 20 °C
and 101.3 kPa Solid (crystalline)
EC number - Melting point 90 °C (dec.)
CAS number 12054-85-2 Density 2.498 g/cm3
IUPAC name Ammonium molybdate
(VI) tetrahydrate Vapour pressure -
Molecular formula (NH4)6Mo7O24 • 4H2O Water solubility 430 g/L (20 °C)
Molecular weight 1235.86 g/mol Flammability
Flash point -
Table 2: Hazard classification and labelling
Substance Name
Hazard
Class and
Category
Code(s)
Hazard Statement
Code(s)
(labelling)
Number
of
Notifiers
Additional
classification
and labelling
comments
Regulatory and
CLP status
Ammonium
molybdate (VI)
(CAS 13106-76-
8)
(EC 236-031-3)
Acute Tox.
4
H302 (Harmful if
swallowed) 82
Number of
notifiers of 17
parties were
summed up.
Not REACH
registered;
Not included in
the CLP
Regulation,
Annex VI;
Included in C&L
inventory
Skin Irrit. 2 H315 (causes skin
irritation) 89
Eye Irrit. 2
H319 (Causes
serious eye
irritation)
89
STOT SE 3 H335 (May cause
resp. irritation) 84
STOT RE 2 H373 (May cause
damage to organs) 1
Aquatic
Chronic 3
H412 (Harmful to
aquatic life with
long lasting effects)
19
Aquatic
Chronic 4
H413 (May cause
long lasting 2
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Substance Name
Hazard
Class and
Category
Code(s)
Hazard Statement
Code(s)
(labelling)
Number
of
Notifiers
Additional
classification
and labelling
comments
Regulatory and
CLP status
harmful effects to
aquatic life)
Skin Sens.
1
H317 (May cause
an allergic skin
reaction)
4
Resp. Sens.
1
H334 (May cause
allergy or asthma
symptoms or
breathing
difficulties if
inhaled)
4
Muta. 2
H341 (Suspected of
causing genetic
defects)
1
Carc. 2 H351 (Suspected of
causing cancer) 1
Appendix 2.2: Sodium nitrite
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Sodium nitrite (mono
constituent substance)
Physical state at 20 °C
and 101.3 kPa solid
EC number 231-555-9 Melting point 217 °C
CAS number 7632-00-0 Density 2.17 g/cm³
IUPAC name Sodium nitrite Vapour pressure 9.9x10-17 hPa (25 °C)
Molecular formula NO2.Na Water solubility 848 g/L (25 °C)
Molecular weight 68.99 g/mol Flammability
Flash point Non-flammable
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Table 2: Hazard classification and labelling
Substance Name
Hazard
Class and
Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
Numbe
r of
Notifier
s
Additional
classification and
labelling
comments
Regulatory and
CLP status
Sodium nitrite
(CAS 7632-00-0)
(EC 231-555-9)
Ox. Sol. 3
H272 (May
intensify fire;
oxidiser)
n/a -
REACH registered;
Included in CLP
Regulation, Annex
VI (index number
007-010-00-4)
Acute
Tox. 3
H301 (Toxic if
swallowed)
Aquatic
Acute 1
H400 (Very
toxic to aquatic
life)
Appendix 2.3: Silicate based corrosion inhibitors
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Calcium metasilicate (mono
constituent substance)
Physical state at 20 °C and
101.3 kPa Solid
EC Number 233-250-6 Melting point 1540 °C
CAS Number 10101-39-0 Density 2.900 g/cm³
IUPAC name Calcium metasilicate Vapour pressure -
Molecular formula CaO3Si Water solubility -
Molecular weight 116.16 g/mol Flammability -
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Calcium borosilicate (mono
constituent substance)
Physical state at 20 °C and
101.3 kPa
Solid (white
powder)
EC Number - Melting point > 1540 °C
CAS Number 59794-15-9 Density 2.65 g/cm3
IUPAC name Calcium borate silicate Vapour pressure -
Molecular formula 1.4 CaO.0.5 B2O3.SiO2.H2O Water solubility 0.34 g/L
Molecular weight 180.1 g/mol Flammability -
ANALYSIS OF ALTERNATIVES
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77
Table 2: Hazard classification and labelling
Substance
Name
Hazard
Class and
Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
No. of
Notifiers
(CLP
inventory)
Additional
classification and
labelling
comments
Regulatory and
CLP status
Calcium
metasilicate
(CAS
13983-17-0)
(EC 237-
772-5)
Not
classified - 335
For reasons of
simplicity the
numbers of
notifiers were
added if the
reported hazard
classification was
identical.
Currently not
REACH registered;
Not included in CLP
Regulation, Annex
VI;
Eye Irrit. 2
H319 (Causes
serious eye
irritation)
166
STOT SE
3
H335 (May cause
respiratory
irritation)
132
STOT
RE2
H373 (May cause
damage to lungs) 166
Calcium
borosiliate
(CAS
59794-15-9)
- - -
No classification
information
available.
Not REACH
registered;
Not included in CLP
Regulation, Annex
VI;
No CLP
classification
notified;
Appendix 2.4: Zinc based corrosion inhibitors
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Zinc (mono constituent
substance)
Physical state at 20 °C
and 101.3 kPa Solid
EC Number 231-175-3 Melting point 409 °C (Zn powder)
CAS Number 7440-66-6 Density 6.9 g/cm³ (22 °C)
IUPAC name Zinc Vapour pressure -
Molecular formula Zn Water solubility
0.1 mg/L (20 °C, pH =
6.93-8.57, powder
form)
Molecular weight 65.409 g/mol Flammability Non-flammable
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
78
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Zinc phosphate (mono
constituent substance)
Physical state at 20 °C
and 101.3 kPa Solid
EC Number 231-944-3 Melting point 846 °C (1013 hPa)
CAS Number 7779-90-0 Density 3.26 g/cm³ (22 °C)
IUPAC name Trizinc bis(orthophosphate) Vapour pressure -
Molecular formula Zn3(PO4)2 Water solubility 2.7 mg/L (20 °C, pH ≈
7)
Molecular weight 386.167 g/mol Flammability -
Table 2: Hazard classification and labelling
Substance
Name
Hazard Class
and Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
No. of
Notifiers
(CLP
inventory)
Additional
classification
and labelling
comments
Regulatory and
CLP status
Zinc
(CAS
7440-66-6)
(EC 231-
175-3)
Pyr. Sol. 1
H250 (Catches
fire
spontaneously
if exposed to
air)
n/a -
REACH registered;
Included in CLP
Regulation, Annex
VI (index number
030-001-00-1)
Water-react. 1
H260 (In
contact with
water releases
flammable
gases which
may ignite
spontaneously)
Aquatic Acute 1
H400 (Very
toxic to
aquatic life)
Aquatic Chronic
1
H410 (Very
toxic to
aquatic life
with long
lasting effects)
Zinc
Phosphate Aquatic Acute 1
H400 (Very
toxic to
aquatic life)
n/a -
REACH registered;
Included in CLP
Regulation, Annex
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
79
Substance
Name
Hazard Class
and Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
No. of
Notifiers
(CLP
inventory)
Additional
classification
and labelling
comments
Regulatory and
CLP status
(CAS
7779-90-0)
(EC 231-
944-3)
Aquatic Chronic
1
H410 (Very
toxic to
aquatic life
with long
lasting effects)
VI (index number
030-011-00-6);
Included in CoRAP-
list
Appendix 2.5: Strong alkaline solutions
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition Potassium hydroxide
Physical state at 20 °C
and 101.3 kPa Solid
EC number 215-181-3 Melting point 406 °C
CAS number 1310-58-3 Density 2.044 g/cm³ (20 °C)
IUPAC name Potassium hydroxide
Caustic potash Vapour pressure -
Molecular formula KOH Water solubility 1210 g/L (25 °C)
Molecular weight 56.10 g/mol Flammability
Flash point -
CRC Handbook
Table 2: Hazard classification and labelling
Substance Name
Hazard Class
and Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
Number
of
Notifiers
Additional
classification
and labelling
comments
Regulatory and
CLP status
Potassium
hydroxide
(CAS 1310-58-3)
(EC 215-181-3)
Acute Tox. 4
H302
(Harmful if
swallowed)
n/a Harmonised
classification
(CLP
Regulation)
REACH
registered;
Included in CLP
Regulation,
Annex VI (index
number 019-
002-00-8)
Skin Corr. 1A
H314 (Causes
severe skin
burns and eye
damage)
n/a
ANALYSIS OF ALTERNATIVES
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80
Appendix 2.6: Phosphate and phosphonate compounds
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition
Trisodium
orthophosphate
Physical state at 20°C
and 101.3 kPa Solid (crystalline)
EC number 231-509-8 Melting point 1583 °C (101 kPa)
CAS number 7601-54-9 Density 2.543 g/cm3 (25 °C)
IUPAC name Trisodium phosphate Vapour pressure -
Molecular formula Na3PO4 Water solubility 145 g/ L (25 °C)
Molecular weight 163.94 g/mol Flammability
Flash point -
CRC Handbook
Table 2: Hazard classification and labelling
Substance Name
Hazard
Class and
Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
Number of
Notifiers
Additional
classificatio
n and
labelling
comments
Regulatory and
CLP status
Trisodium
orthophosphate
(CAS 7601-54-9)
(EC 231-509-8)
Skin Irrit. 2 H315 (causes
skin irritation) 689
25
Notifications
, 1 joint
entry
REACH registered;
Not included in CLP
Regulation, Annex
VI
Eye Irrit. 2
H319 (Causes
serious eye
irritation)
332
STOT SE 3
H335 (May
cause resp.
irritation)
229
Eye Dam. 1
H 318 (Causes
serious eye
damage)
377
Skin Corr.
1B
H 314 (Causes
severe skin
burns and eye
damage)
84
Skin Corr.
1A
H 314 (Causes
severe skin 13
ANALYSIS OF ALTERNATIVES
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81
Substance Name
Hazard
Class and
Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
Number of
Notifiers
Additional
classificatio
n and
labelling
comments
Regulatory and
CLP status
burns and eye
damage)
Skin Corr.
1C
H 314 (Causes
severe skin
burns and eye
damage)
3
Met. Corr.
1
H 290 (May be
corrosive to
metals)
3
Acute Tox.
3
H 331 (Toxic if
inhaled) 3
Appendix 2.7: Rare earth metal salts
Table 1: Substance IDs and properties for relevant substances:
Parameter Value Physicochemical
properties Value
Chemical name and
composition Cerium trinitrate
Physical state at 20 °C
and 101.3 kPa Solid (crystalline)
EC number 233-297-2 Melting point 57 °C
CAS number 10108-73-3 Density 2.4 g/cm³ (20 °C)
IUPAC name Cerium trinitrate Vapour pressure < 8.17 *10-7 Pa (20 °C)
Molecular formula Ce(NO3)3 Water solubility > 600 g/L
Molecular weight 326 g/mol Flammability
Flash point Non flammable
ANALYSIS OF ALTERNATIVES
Use number: 1 H&R Ölwerke Schindler GmbH, H&R Chemisch Pharmazeutische Spezialitäten GmbH
82
Table 2: Hazard classification and labelling
Substance Name
Hazard Class
and Category
Code(s)
Hazard
Statement
Code(s)
(labelling)
Number
of
Notifiers
Additional
classification
and labelling
comments
Regulatory and
CLP status
Cerium trinitrate
(CAS 10108-73-
3)
(EC 233-297-2)
Ox. Sol. 3
H272 (May
intensify fire,
oxidizer)
9
141 notifiers,
1 joint entry
REACH
registered; Not
included in CLP
Regulation,
Annex VI
Ox. Sol. 2
H272 (May
intensify fire,
oxidizer)
78
Ox. Sol 1
H271 (May
cause fire or
explosion,
strong oxidizer)
25
Eye Dam. 1
H318 (Causes
serious eye
damage)
83
Aquatic Acute 1
H400 (very
toxic to aquatic
life)
103
Aquatic Chronic
1
H410 (very
toxic to aquatic
life with long
lasting effects)
103
Eye Irrit. 2
H319 (Causes
serious eye
irritation)
57
Skin Irrit. 2 H315 (Causes
skin irritation) 11
STOT SE 3
H335 (May
cause
respiratory
irritation)
Aquatic Chronic
3
H412 (Harmful
to aquatic life
with long
lasting effects)