Presentation to NACE Middle East

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Presentation to NACE Middle East African Branch

• Corrosion Under Fire Protection
• - Ian Bradley, International Paint Saudi Arabia
  Limited (IPSAL)

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Contents

• Types of passive fireproofing (PFP)
• Commonly found corrosion problems
• Corrosion testing for PFP systems
• UL exterior listing
• Norsok
• Comparison
• Guidance for specifying PFP systems in corrosive
  environments
• Summary
• 20 25 minutes
• Questions Answers session

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Types of passive fire protection

• Dense Concrete
• Lightweight Cementitious
• Solvent based and solvent free Epoxy intumescents
  
• Subliming materials
• Mineral Wool (and other insulations)

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ISO 12944 C5

• ISO 12944 developed to assist engineers
• Global standard
• Designates environments according corrosivity
• Based upon corrosion of steel lt 120ºC
• C5 - M superseded by ISO 20340
• Addresses corrosion aspect but not fire
  performance
• A typical plant may encompass several
  environments
• Jetty
• Areas around cooling water towers etc

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Some examples of corrosion beneath passive fire
protection
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Examples of corrosion behind PFP
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Corrosion cycle
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Loss of passivation effect

• Acidic industrial atmosphere
• Decrease in pH
• Leads to loss of passivity
• Active corrosion beneath cementitious materials

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Examples of corrosion behind PFP
Corrosion beneath concrete fireproofing C5I
environment (Southern Europe)
Note significant thinning of section flange
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Examples of corrosion behind PFP
Pitting corrosion behind lightweight cementitious
fireproofing C5I Pitting corrosion caused by
ingress of calcium chloride during maintenance on
vessel LPG drier in refinery
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Examples of corrosion behind PFP
General corrosion behind delaminated fireproofing
material C5 - M Structural steel offshore
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Examples of corrosion behind PFP
Delamination of topcoat and subsequent
deteoriation of passive fire protection material
C5-M Structural steel offshore
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Examples of corrosion behind PFP
Severe corrosion of structural I sections beneath
fireproofing Chemical Plant USA (C5-I)
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Examples of corrosion behind PFP
Gas pipe-work support structure Structural steel
onshore C4 / C5-I
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Examples of corrosion behind PFP
Process vessel and structural steel
offshore Structural steel offshore C5 -M
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Examples of corrosion behind PFP
LPG Sphere Leg Structural steel onshore C5 - M
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Some contributing factors

• No coating or inadequate coating beneath
• Testing of fire monitors containing water or
  worse seawater
• Lack of flashing plates / sealing caps
• No stand off
• But no bond to surface either
• Non destructive NDT difficult / impossible

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When specifying fire protection materials

• What do engineers concentrate on?
• Fire performance
• Fire duration
• Critical core temperature
• Type of fire (hydrocarbon, cellulosic, jet fire)
• Cost (Fire protection is a major cost item on new
  plant)
• Still too little emphasis on durability and
  weatherability

For fire protection to be effective it must be
present and intact at the time of the fire
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How do we define intact?

• Many ways you could define intact
• Unaltered from as built condition
• Free from significant amounts of water
• Bonded to the substrate
• Whole (i.e. free from cracks, corrosion paths
  etc)
• But we need something subjective!!
• i.e. test standard
• High impact if wrong decision is made

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Early attempts to measure weathering

• DiBt
• German standard for fireproofing
• Requires non-accelerated weathering samples
• Fire tested at regular periods
• Cellulosic fire protection (buildings)
• Long time periods involved
• GASAFE
• LPG fire protection program
• 1990s
• Tried to address weathering aspect
• Limited success

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More Recent Attempts

• UL1709
• UL 1709 addresses fire performance
• Exterior listing addresses weathering
• Accelerated weathering
• Will then list complete system
• Follow up service compliance with as tested
  material
• NORSOK
• Numerous revisions (covered later)
• Designed for offshore (C5-M)
• Accelerated weathering
• Generic type based
• Two categories

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UL 1709 Exterior Listing
Test Standard Comments
Aging Circulating oven 70ºC for 170 days
Humidity - 97-100 humidity, 180 days
Industrial atmosphere - 1 SO2 / 1 CO2 in chamber water. 95F for 30 days
Salt spray ASTM B117 90 days salt fog testing
Wet Freeze Dry Cycling - 0.05 mm/ s water for 72 hours,-40ºC for 24 hours,60ºC for 24 hours repeated for 12 cycles
Fire testing UL 1709 Must meet original acceptance criteria
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Norsok M501 Revision 5
Test Standard Comments
Ageing resistance ISO 20340 See below
Salt Spray ASTM B117 Artificial seawater, 35ºC, 72 hours
Low temperature -20ºC 24 hours
UVA/Condensation ASTM G53 UVA exposure followed by 100 condensation
Adhesion ISO 4624 Adhesion lt 50 reduction from, gt original gt 3MPa
Scribe Creep - lt 3mm
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Norsok M501 Revision 5 - continued
Test Standard Comments
Blistering, rusting cracking, ISO 4628 Rating 0 for all
Water absorption - Shall be reported
Fire testing - Fire testing to 400ºC critical core temperature for 60 minutes within 10 or original unexposed test
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Norsok M-501 Revision 5 versus Revision 4

• Salt spray and freeze/dry is now a combined cycle
• Revision 4
• Salt spray/drying (ISO 7253) UV-A (G-53) 4200
  hours
• Water / freezing / drying / humidity ISO 2812-2
  4200 hours
• Evaluation of scribe creep has changed
• Tested without top-coats

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Corrosion Issues with major generic types

• Dense concrete
• Prone to damage
• No bond to substrate (undercutting)
• Can retain significant amounts of water
  (spalling)
• Passivation lost with time in marine / industrial
  environments
• Needs weather cap / sealing

• Lightweight cementitious
• Prone to damage
• No bond to substrate (undercutting)
• Application must be correct
• Similar to dense concrete
• Needs Weather cap / sealing

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Corrosion Issues with major generic types

• Mineral Fibre / Cladding
• Prone to damage
• Very absorbent once cladding damaged
• Salts in mineral wool may contribute
• Needs weather cap / sealing

• Epoxy
• Offer many performance advantages, however,
• Generally fire performance / weatherability is a
  balance
• Number of materials where balance is incorrect
• More sensitive to application
• Careful (and detailed) specification is necessary

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Some general trends

• Cement based and mineral fibre systems no longer
  used in C5-M
• Cannot exclude problems in C5-I
• More awareness of extent of C5-M environment
• Jetties
• Coastal Refineries other locations
• Awareness of these corrosion issues
• Not translated into action in many parts of
  industry
• Corrosivity of project location remains
  un-established (Quantitatively)

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Guidance for specifying PFP performance

• Be aware of the problem
• Know your environment
• Question existing practises
• Materials
• Construction details
• Consider key areas and potential for upgrade
• Consider suitable weatherability criteria
• UL / Norsok
• In conjunction with fire performance
• These are safety critical decisions

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Demonstrated performance by case history

• Applied in 1976
• Inspected and analysed
• BAM - 1992
• No chemical changes in material detected
• Intumescent chemicals unaffected
• C5-M Refinery (The Netherlands)

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Conclusions

• Corrosion behind some types of passive fire
  protection is a real risk
• Durability is as important as initial fire
  performance
• Test procedures exist which can distinguish
  materials performance
• Recognised and workable standards
• Available to use

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Questions
Ian.Bradley_at_AkzoNobel.com