OH&S practices as a cause of corrosion under insulation?

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Graham CarlislePrincipal Corrosion and Coating Engineer

TOPICS

4. OH&S “SAFE TO TOUCH” specs

5. ISSUES WITH INSULATION

7. MAINTAINING COMPLIANCE

2. WHY INSULATE

3. TYPES OF INSULATION

10. CASE HISTORYMEG VSESSELS

11. CONCLUSION

8. THERMAL INSULATION COATINGS

9. TESTING

1. THERMAL PROPERTIES OF

MATERIALS

6. MITIGATION OF CUI

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Heat transfer

Conduction Radiation Convection

www. coolcosmos.ipac.caltech.edu

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Thermal conductance

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Thermal conductance

𝑸ℎ𝑒𝑎𝑡 𝑓𝑙𝑜𝑤 = −𝒌Δ𝑻𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑖𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒

𝑳𝑚𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠

k = thermal conductivity, where 𝑘 = 𝑘𝑙 + 𝑘𝑒

Q is measured in W/m2 and k in W/m-K

Therefore, in a time rate of steady state heat flow through a unit area of a material

𝐶𝑜𝑛𝑑𝑢𝑐𝑡𝑎𝑛𝑐𝑒 =𝑘

𝐿

W.D. Callister, Chapt. 19- Materials Science and Engineering

Normal lattice positions for atoms

Positions displaced because of vibrations

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Thermal inertia

Photograph courtesy of Lockheed Missiles & Space Company, Inc.

Silica fibre insulation

Internal temperature = 12500C

(white-hot)

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Why insulate?Thermal energy conservation

• Use materials with low thermal conductivities

• Limit transfer of thermal energy

• Insulate hot process from heat loss

• Isolate cold process from heat gainwww.aerogel.org

To provide:

Operational stability Energy efficiency Equipment reliability

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Personal protection

B o s c h u n d s i e m e n s h a u s g e r ä t e g r u p p eISO 13732-1

1. No Burn2. Burn Threshold3. Burn

Time in secs

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Types of insulation-Inorganic

Calcium Silicate Mineral wool

Foam glass PerliteVermiculite

Aerogel

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Types of insulation-Organic

Polyisocyanurate

Polyurethane

Rigid phenolic foam

Various Elastomers

Polyethylene

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OH&S Specifications for “Safe to Touch”

Surfaces operating at temperatures in excess of 60ºC

(140ºF) shall be fitted with personnel protection,

consisting of SS 316 metal mesh guard.

Operating above 60-700C

Any area that is accessible

2.1m vertically above grade or from platforms

0.9m horizontally from periphery of platforms, walkways or ladders.

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Alternative personal protection

Expanded diamond SS mesh Physical hard barriers

Perforated SS mesh (L)Perforated SS mesh (S)

Bound wire HDG mesh

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Corrosion associated with insulation-General & Localised

General & localised corrosion from moisture ingress due to damaged cladding and failed joint

M. Chauviere, MoniCorr Inc.

www.flowgeeks.com

Chloride (Sulphide) induced stress corrosion cracking

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Corrosion associated with insulation-Galvanic Corrosion

M. Chauviere, MoniCorr Inc.

Galvanic corrosion from dissimilar metals due to no isolation between cathode and anode

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Corrosion associated with insulation-Crevice Corrosion

Mitigation of CUI

Insulation specification

• Closed cell foams/Aerogels (hydrophobic)

• Low chloride

• Low moisture

Design detail to prevent water ingress• Top hats to shed water• Arrange cladding to shed water• Drain points at the base of long vertical sections• Waterproof seals on pipe hangers and supports• Avoid joints in steam tracing lines

Dry construction• Dry storage during shipment and storage• Protection during construction

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Mitigation of CUI

Protect the substrate

• Organic coatings (carbon and stainless steels)

• Aluminium foil (austenitic stainless steel)

• Inhibited insulation (silicates for the SCC of austenitic S.S.)

Prompt maintenance/repair of damaged cladding

Warm air drying (recent development - limited application)

Review the need for insulation:• Lower temperatures later in life• Use guards rather than insulation for personnel protection• But, beware the possibility of introducing internal dew-point

corrosion risks

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Mitigation of CUI- Inspection

Removable “windows” in cladding/insulation

Remove insulation (common practice)

With insulation in place:

• Neutron back-scatter

• Other novel NDE techniques

Thermal imaging

• Detects insulation breakdown (implies water present)

Radiography

• Detects corrosion thinning of pipe/vessel wall

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Maintaining compliance-PP

Removing insulation or SS mesh

1. OH&S to consider thermal inertia properties of various materials in specifications

2. Use thermal insulation coatings to protect and modify surface

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Thermal insulation coatings

Binders

• Acrylic

• Water Based Epoxy

• Hybrid Acrylic/Epoxy

• Polyurethane

Pigments

• Hollow glass microspheres

• Silica aerogels

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Testing of thermal insulation coatings

Acrylic Coating

Insulation Technology

Approximate Thermal Conductivity (mW/m-K)

Average ApplicationThickness- one coat (mm)

Thermal Resistance per Pass (x103m2K/W)

A Aerogel 35 1.5 42.9

B Ceramicmicrospheres

70 0.5 7.1

C Ceramic microspheres

100 0.375 3.8

D Ceramic microspheres

100 0.375 3.8

E None 300 0.1 0.3

P. Pescatore et. al., PCI Journal, 03/07/2013

Test Procedure Average Values Obtained Comparative Bench

Mark Values

References

Corrosion resistance:

Cyclic wet/dry test

(Prohesion)- G85-11

and D1654 – 08

No visible corrosion or

coating defects after 500

hours of exposure.

Rating of:

9 for plate 1

9 for plate 2

9 for plate 3

No visible corrosion or

coating defects after

500 hours of exposure.

9 for epoxies

The Effect of Four

Commercially Available Steel

Decontamination Processes

on the Performance of

External Coatings NACE

corrosion paper, San Antonia

Conference, 2014.

Performance of Dry

Film-Moisture vapour

transmission rate-

D1653-13

14 g/m2/24hr Low < 15g (m2d)-1 EN ISO 7783-2:2001

Flexibility of cured

film- D522-93a(2008)

500 mm Pass (cold)

50 mm Pass (hot)

No published values Flexibility and Toughness,

John Fletcher and Joseph

Walker in Paint and Coating

Testing Manual-15th. Edition

of the Gardner-Sward

Handbook

Test Procedure Average Values Obtained Comparative Bench

Mark Values

References

Adhesion of cured

film- D4541-09e1

2.53 MPa Un-exposed

4.6 MPa Cyclic wet/dry

2.47 MPa thermal cycling

4.4 MPa EPX4 to various

substrates

8.2 MPa NanoPrime to

Various substrates

(all cohesive failures)

350 psi (2.4 MPa)

5 MPa

Nansulate EPX4 data sheet

Norsok M-501

Resistance to thermal

cycling- D6944 − 15

No checking

No blistering

No cracking

No checking

No blistering

No cracking

The Effect of Four

Commercially Available Steel

Decontamination Processes

on the Performance of

External Coatings NACE

corrosion paper, San Antonia

Conference, 2014.

Thermal resistivity of

cured film-

C335/C335M-10e10.071 W/m.K (thermal

conductivity)

~0.060 W/m.K at 70%

PVC (thermal

conductivity)

Quantitative analysis of silica

aerogel-based thermal

insulation coatings, Søren

Kiil in Progress in Organic

Coatings, 2014

Validation of ‘safe-to-touch’

H. Mitschke & G. More, Mascoat, NACE PP paper

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Validation of ‘safe-to-touch’

H. Mitschke & G. More, Mascoat, NACE PP paper

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Validation of ‘safe-to-touch’

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Case study: thermal insulation coatings

OVERVIEW

The client had a number of process vessels and piping that operated above the ‘safe to touch’ temperature, in accessible locations. Previous strategies using traditional insulation/cladding and metallic shields had led to either CUI or bi-metallic corrosion.

SOLUTION

• IAS employed the use of a patented formulation of a thermal insulation coating

• Conducted a thermal survey to establish hot-spots and high risk areas

• Specified the appropriate thickness in order to achieve the required temperature reduction

• Applied the Nansulate coating system and ensured hot surfaces complied with HSE policy

Removes the need for traditional insulation Live system application & 30% quicker to apply Small footprint for equipment & reduced logistics

Structure Glycol regeneration package

Application Type Texture sprayer

Operating Environment 3 vessels

Surface Preparation Power tool cleaning

Diameter 1.1m

Operating Temperature 80 -110C

Safe to Touch Temperature 68C

Corrosion Type Corrosion under insulation (CUI)

Proven Technology • Nansulate Heatshield EPX4• NanoPrime

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Case study: Thermal insulation coatings

Test pointsGlycol Flash Vessel38-VD-002 (3 coats)

Glycol Surge Vessel38-VL-005 (3 coats)

Cold Glycol Heat Exchanger38-HF-003 (6 coats)

Vessel shell Day 1 Day 30 Vessel shell Day 1 Day 30 Vessel shell Day 1 Day 30

Aft 660C 460C 590C 680C 510C 550C 840C 620C 750C

Centre 570C 510C 600C 690C 480C 650C 880C 630C 720C

Forward 630C 380C 540C 710C 450C 730C 840C 560C 510C

Operating temp ~700C ~700C ~900C ~740C ~740C ~940C ~900C ~900C ~1100C

Day 30Vessel 38 HF 003 (aft end mid level)Magnetic thermometer reading 800CInfrared reading 1030C

Day 1Vessel 38 HF 003 (aft end mid level)Thermocouple reading 620C

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Conclusion Traditional insulation materials for high/low temperature applications,

critical processes requiring thermal energy conservation

Liquid TIC can be used for uninsulated systems requiring improved

efficiencies and operating at -10 to 2050C

Liquid TIC for insulated systems are ideally for use where insulation was

predominantly installed for personal protection

TIC’s reduce incidence of CUI and as well as protecting the asset

Overall cost of installation is lower for TIC compared to traditional insulation

and the ease of insulation of irregular geometries is significantly better

TIC’s OH&S complaint???

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Thank you!

Questions?

Graham CarlislePrincipal Corrosion and Coating Engineer