A presentation on Upgraded Insulation Systemsby
N. SrinivasLloyd Insulations India Limited
LLOYD INSULATIONS (INDIA) LIMITED
Thermal Insulation
A provision made to retard heat flow from a hot surface to a cold environment from a warm environment to a cold surface
This simple device in Industry has acquired enormous importance in recent times for what it can do for us if we were to give a very little extra attention
Today’s need is for Correctly designed and well installed
insulation system….
Which is Easy on the purse
Speedy to erect
Stays maintenance-free & Efficient in service
An efficient insulation in place serves our best interests
in today’s context
Economy: safety :smoother process control at Plant level
Substantial reduction of fuel costs & enhanced profitability at the corporate level
Reduction of Greenhouse gas emissions at the larger Global level
There is urgent need for thrift in our energy consumption pattern. Poor insulation is a major drain on energy and resources in industry today…
There is an urgent need to have a close look at what it means to specify correct performance levels in insulation.
Potential for energy loss from a hot surface
From a metallic surface at 30 C ambient temperature and wind
velocity 3m/sec
Difference between
ambient and surface
temperature°C
Heat loss kcal m2.hr
25
40
100
150
225
340
600
1910
3225
5330
Heat-in-leak into cold surfaces
Difference in
Temperature between
ambient & Surface
°C
Heat in-leak
Kcal/m2h
Exposed area per
Tonne of
refrigeration m2
5
10
15
20
38
76
125
165
79
40
24
18
Ambient considered : 38 C Surface Absorptance:0.8
Shape of Surface : SphericalProperly designed insulation can restrict the above valuesdown to 10 - 15 kcal / M
Heat Transfer through Mass Insulation
Components of Heat Transmission
Thermal Insulation
From this, we can see that
insulation is a major tool in
improving “energy
availability”
Financial Implications of Performance Specs
0
50000
100000
150000
200000
250000
300000
40 50 60 70 80 90
1982
1988
1991
1998
2004
2008
System details:Pipe Dia-(NB): 100mmSurface Film Coeff
:12kcalm2hr CAmbient Temp : 29 CHours of Operation : 8000
YearsConversion Eff.: 100%
Surface Temp. over
insulation in C (specified)
Co
st o
f lo
st h
eat
/ 1
00
mtr
s /
ann
um
in
Rs.
Economic reasons for Thermal insulation in industry
Reduces fuel consumption, and hence overall cost of operation
Reduces capacity requirements for heating/cooling systems (e.g., boilers/ refrigeration units, etc)
Benefits of higher profits to owner
Savings in Project Capital costs
Economic Thickness
0 1 2 3 4 5 6 7 8 9 10 11
TOTALCOST
LOSTHEAT
COST
INSUL
ATION
COST
CO
ST P
ER Y
EA
R, R
S
INSULATION THICKNESS, INCHES
MINIMUM
COST
The basic criterion for thermal insulation is Economics…
However, major role of Insulation is in helping in attaining equilibrium of Process temperatures, while
assuring safety against burns in a plant
The ‟Insulation System‟ is the barrier against avoidable heat transmission.
Any amount of care in design and implementation is worth the trouble
Thermal Insulation Systems- Importance Of “Design”
The function of Thermal insulation is performed not just by a single material, but by an assembly of engineered provisions or components termed as, “Thermal Insulation System”. As called for in all such works, there is need for careful “design” of all such elements.
The task of the insulation designer is to evolve system which fit the need-like a glove to a hand that would wear it.
Insulation System Design
Insulation system should perform to the expected level, undiminished over its life.
This needs full data on material behavior under all conditions of exposure.
In particular, designers need to know what would make a material lose its properties.
Features of a material are important-but their limitations are even more so!
The hazards of being an insulation designer is that we have many manufacturers whose data are simply not reliable or representative.
We have to evolve our own database for properties of materials-insulants, adhesives,
cements, or specialities.
We, at Lloyds have been actively generating and reviewing such databases for all these years...
Insulation design
Thermal designs are carried out using well researched calculation protocols.
Design of the physical system poses maximum challenge since it needs in depth knowledge of what\makes materials work and what makes them fail. It needs detailed study of system dynamics.
Take for example, the design to take into account moisture entry ,expansion and contraction etc when the pipe or vessel is heated up and/ or cooled down-cyclically.
Design for thermal growth or shrinkage
It needs a very detailed analysis of each layer of insulation, the effect of the temperature at that layer, a comparison with what the metal surface may have undergone due to change in the temperature the metal may have seen.
Relative growth of one or the other element, unless factored in, becomes the source of damage and breakdown...
Design for thermal growth or shrinkage
Relative growth of one or the other element, unless factored in, becomes the source of damage and breakdown...
7500
Properties of Materials in insulation
Some important details of what makes them work and what makes them fail
Factors in selection of Thermal Insulating Materials
Significant parameters involved are:
Thermal Properties
Mechanical Properties
Chemical Properties and
Commercial Factors
Although listed last, commercial factors play animportant role in our choices.
Broad material properties to consider in
selecting materials
Is it Alkaline or is it acidic (pH)
Chemical Reactivity / passivity to MOC
Combustibility
Compressive Strength & Breaking Load
Is it prone to water ingress due to Capillarity
Is it Abrasive? and, Most importantly,
THERMAL PROPERTIES
Thermal Properties of Insulation Materials
Important thermal parameters of thermal insulation materials are
Temperature resistance- limiting service temperature
Thermal conductivity
Coefficient of Expansion / Contraction
Thermal diffusivity, and
Thermal shock resistance
Thermal Insulation Materials
Chemical Properties
Compatibility with the metal surface
Compatibility with environmental media
Rate of deterioration arising out of the above-if any
Expected life of insulation material
Thermal Insulation materials are made of many basic forms
Flake : Vermiculite, Mica
Cellular : Polyurethane foam (PUF), Foam glass, Expanded Polystyrene, Cellular concrete
Granular: Calcium Silicate, Magnesia & Perlite
Fibrous : Mineral fibres, ceramic fibres
A material can be a combination of any of the above as
Well (e.g. Microporous insulation)
Thermal Insulation Materials
Extra Low Thermal Conductivity Materials
Microtherm
Pyrogel / Cryogel
Micro porous insulation
Long “chains” of SAS particles help to keep
solid heat conduction to a minimum.
Spaces in the structure smaller than the mean
free path of an air molecule eliminate most of
the gaseous heat conduction.
Mineral oxide opacifiers effectively block infra
red radiation.
Microporous insulation is based on nano-structured sub-micron synthetic amorphous silica („SAS“) and other environmentally safe materials.
Microtherm
What are Aerogels?
Nanoporous solid
Aerogels refer both to a structural morphology and a method to produce them (supercritical extraction from gels)
Open-cell structure with up to 99% open porosity (our blanket is 93-95% open volume)
Translucent silica aerogels are often called “frozen smoke”
Average pore diameters of 10 nm create unique
properties
Reduced mean free path for gas molecules
Reduced energy and mass transport
Traditional silica aerogels are weak and brittle
Lowest k-Value
0
20
40
60
80
100
120
-200 -100 0 100 200 300 400
Mean Temperature ( C)
Th
erm
al
Co
nd
ucti
vit
y,
k(m
W/m
-K)
0-100-200-300 100 200 300 400 500 600 700
Mean Temperature ( F)
Th
erm
al C
on
du
ctiv
ity, k(B
tu-in
/hr-ft
2-F
)
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Pyrogel
Expanded
Perlite
Mineral Wool
Calsil
Thickness Comparison
Hot Insulation Materials manufactured on commercial scale..
Rockwool / Mineral wool- by far the most widely manufactured worldwide
Calcium Silicate- limited to countries where raw materials are available.
Ceramic Fibre- its high refractoriness making it a material of choice for high temperatures
Foam Glass-predominantly specified for low temperatures and load bearing applications
Fibrous Materials Raw materials like rocks, minerals and others used
as additives and correctives are available in plenty-particularly in India
They are made using dry processes- hence are free from contaminants normally associated with process water.
They are easily available in various usable forms: Blankets, Semi-rigid slabs, or preformed pipe
sections
Moulded blocks and shapes
Loose fill
Encapsulated / laminated constructions
Sprayable and cement type formulations
for trowel application
Commonly used Hot Insulation Materials
Mineral wool : our Rockloyd range
Rockloyd Mattress
Rockloyd Slab
Rockloyd Pipe sections
- Conform to IS 8183, BS 3958 &ASTM-C-592/ C-612 IS 9842& C-
547.
- Incombustible when tested as per IS 3144
- Concurrently approved as A-15, A-30 & A-60 Class fire barrierinsulation under SOLAS,
Selection of Insulation Materials
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
38 93 149 204 260 316 371
Mean Temperature °C
Therm
al C
onductiv
ity W
/m°C
Rockwool Pipesections (ASTM C 547)
Perlite (ASTM C 610)
Calcium Silicate (ASTM C 533)
Insulation Materials for High Temperatures
Ceramic Fibre: Supercera range
(RT grade up to 1260 C
HT Grade up to 1430 C )
Supercera needled Blankets and fabrications such as:
Folded modules
Encased flexible sections
Supercera Bulk Fibre
Supercera rigid Boards / Vacuum formed blocks & Shapes
Moist felt / Paper / Rope
Calcium Silicate.
Insulation Materials for High Temperatures
Ceramic Fibre: Supercera range
Also used as Fire protection in
Structural Steel applications
Cable Trays
Ship Bulkheads / deckheads
Turbine Insulation
Removable Type Pads
Supercera Ceramic fibre Removable Pads for Turbine Insulation
Commercial Cold Insulation Materials
Polyurethane Foam (PUF)
Polyisocynurate Foam (PIR)
Foamglass
Phenolic Foam
Expanded Polystyrene (EPS)
Low Temperature Insulants
Among the listed materials, Polyurethane and Polyisocyanurate, representing products of lowest Thermal conductivity are materials of choice because of the easy availability in commercial quantities and the versatility they offer.
As is well known, these materials offer great flexibility to the specifier and user since they can be applied as Preformed shapes or installed in-situ- by Pouring or by spray.
Urethane Foams-the ultimate cold insulant..
Rigid Urethanes Foams are a family of Engineered Plastics which have received enormous R&D inputs worldwide.
Today, any features that an application may demand can be built in by careful selection of chemical ingredients and precise engineering of their chemistry.
Insulation Finishes
The outer cover over insulation..
Weather Barriers/ claddings- These all have one basic function - to protect insulation from the known hazards like external media, mechanical abuse etc.
External coverings are what we get to seeing in a completed plant or pipeline. Aesthetics becomes a secondary, but significant role assigned to this provision.
Insulation Finishes
Metal Cladding- some important issues..
As can be easily appreciated, all metal cladding materials need careful selection from external corrosion point of view as a first consideration.
However, another important aspect concerns corrosion from within- contributed by condensation of vapours from the insulation system on the inner surface.
Since most insulants are faintly alkaline, such condensed water attacks the metal – particularly Aluminium and causes it to pit and fail as a barrier.
All metal cladding, as a rule need protection on the inner surface- like a factory laminated Poly Surlyn treatment.
Cladding Materials
Metal Claddings with Moisture Barrier
PolySurlyn
Polyethylene
Surlyn
Polyethylene
Metal Corrosion
Pits
Weather Barrier
Installed on outer surface of thermal insulation, these protect the insulation from the weather (rain, snow, sleet, wind), solar radiation, or atmospheric contamination & mechanical damage.
They significantly contribute to protection of the insulant and play a vital role in the life of the system.
Being the final exposed surface, its selection involves study and knowledge of all external and environmental factors the system is to encounter.
Metallic claddings
As is well known, metallic sheeting fabricated into close conforming cover, with edge detailing to lap and seal effectively, is probably the most popular external cladding.
However, Plastics, like High Density Poly ethylene (HDPE), PVC and special polymers are specified for niche applications / duties.
Most popular metal cladding is based on Aluminium- in specific alloy grades for specific duties.
When steels are specified, they are either of suitable grades of SS or of Carbon steels with a metallurgical protection like galvanizing, Aluminizing or a treatment consisting of a combination of Zinc and Aluminium.
Outer Cladding Systems for Insulation
Metallic Cladding Materials
Aluminium or Galvanised Steel Bare or Colour coated.
Zincalume or Aluminised Steels
Stainless Steel
Other cladding systems
Cementaceous plasters
Liquid applied reinforced Coatings
HDPE and PVC sheets / sleeves
Vapour Barrier in cold service
Installed on the high vapour pressure side-I.e., the warmer side of the insulation systemprior to cladding), Vapour Barrier (or Vapour retarder as it is referred sometimes) is designed to arrest entry of moist vapour into the insulation, causing it to soak and possibly to freezing.
Insulating Material, when wet can be 30 times more conductive and would no longer be an insulant!
Freezing of water is always accompanied by volumetric expansion resulting in rupture.
In cold insulation system, therefore, the soundness of the VB virtually determines how good the insulation system is.
Vapour Barrier in cold service
Weather cum Vapour Barrier
There are a set of materials, which serve both as a weather barrier and vapour retarder at the same time.
These are mostly in the form of Mastics- trowelled or brush applied- which set to becoming a tough outer skin.
Important factors in cold insulation
Adequacy of insulation to limit heat ingress to be below process limits.
Adequacy of thickness to prevent condensation on the exposed surfaces- this involves the emittance of the surface. A reflective surface like Aluminium would call for very high insulation thickness to prevent surface condensation. Colour coating is a very effective solution.
Prevention of water vapour transmission fromthe warm side to the cold side of the insulationhas to be ensured under all conditions- i.e., thesystem should feature a good Vapour Barrier.
A word on Vapour Barriers..
Often Bitumen and products are used. These are not fire-safe, durable nor Elastomeric- which are all veryimportant needs.
These materials once in wide use have no place in thepresent day Insulation specifications.
Excellent Vapour Barrier products are now available andno compromise is therefore necessary
Insulation Pipe supports
Today’s plants need a wide expanse of extremely low temperature piping.
Unless supports are highly insulating, the exposed surfaces would attract condensation and very heavy corrosion at these important bearing points- with corroded load bearing points and avoidable unsafe slippery floors underneath.
SUPERTHERM Pipe supports
These are made from Highest efficiency insulants i.e., Urethanes, made to high density to afford an Engineered load bearing capacity.
These are made in all the possible shapes and with specific features- for sliding, guide and anchor duties.
Support design and selection are very vital design inputs for the Process Piping Engineeer / designer.
Thermal Insulation for Cryogenic Temperatures
Fields calling for cryogenic engineering
Storage & handling systems for Cryogenic liquids- LNG
Air seperation and N2,O2,Inert gas plants
Rocket Fuel handling Systems in Dept of Space
Environment Simulation Chambers for Space programs
Nuclear Engineering- liquid H2 plants, materials development
Electronics- Superconductivity studies
Biological Applications
Food preservation
Special Manufacturing Processes
Thermal Insulation for Cryogenic Temperatures
INSULANTS FOR CRYOGENIC DUTY: Mass type materials which qualify for this duty up to -160 C
are:
- Cryogenic grade Polyurethane / Polyisocyanurate
- Cellular glass
Cladding System for Shell Insulation
Lloyd Standing Seam „SS 2000‟ Tank Cladding system
The SS 2000 profile is site roll formed using
Zimmermann Roll Former which permits
rolling any length as required. Normally, a
length over 12 mtr is not transportable and
hence site roll forming offers this advantage.
Maintainability of Insulation
One of the aspects which suffers badly due to these factors is the Maintainability of insulation.
When specialist agencies are given the responsibility to design and detail out the system, good engineering practices are automatically built in.
These get diluted badly when low cost and haste become the buzzwords!!
Maintenance of Insulation
There are many places where damages almost always occur:
Gaps or unsealed joints admit water through poor weather barrier jacketing
Job done without expansion breaks rips the cladding, Spillage ruins the weather-barriers, and soaks into the
insulation through unprotected edge detail. Unfilled projections through the insulation cause
disintegration of the weather-barrier and result in peelback
sealant in Weather-barriers shrinks and cracks admitting water freely.
Foot loads coming as a surprise on a design not capable of bearing them.
Maintenance of Insulation
Insulation when selected properly and installed wellis an excellent investment, and good maintenanceprotects that investment. Poorly applied insulation isa large drain on resources - both in terms of poorerEnergy economics and in terms of higher costs ofrecurring maintenance that it entails.