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Corrosion Under Fire Protection - Types, Testing, and Solutions

This presentation by Ian Bradley of International Paint Saudi Arabia Limited explores the types of passive fireproofing, common corrosion problems, and testing methods for fire protection systems. It also discusses UL exterior listing, Norsok standards, and guidance for specifying PFP systems in corrosive environments.

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Corrosion Under Fire Protection - Types, Testing, and Solutions

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  1. Corrosion Under Fire Protection - Ian Bradley, International Paint Saudi Arabia Limited (IPSAL) Presentation to NACE Middle East & African Branch

  2. 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

  3. Types of passive fire protection • Dense Concrete • Lightweight Cementitious • Solvent based and solvent free Epoxy intumescents • Subliming materials • Mineral Wool (and other insulations)

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 120ºC • C5 - M superseded by ISO 20340 • Addresses corrosion aspect but not fire performance • A typical plant may encompass several environments • Jetty • Areas around cooling water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

  5. Some examples of corrosion beneath passive fire protection

  6. Corrosion beneath concrete fireproofing – C5 I environment (Southern Europe) Vessel support structure Examples of corrosion behind PFP

  7. Corrosion cycle

  8. Loss of passivation effect • Acidic industrial atmosphere • Decrease in pH • Leads to loss of passivity • Active corrosion beneath cementitious materials

  9. Examples of corrosion behind PFP Corrosion beneath concrete fireproofing – C5I environment (Southern Europe) Note significant thinning of section flange

  10. 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

  11. Examples of corrosion behind PFP General corrosion behind delaminated fireproofing material C5 - M Structural steel offshore

  12. Examples of corrosion behind PFP Delamination of topcoat and subsequent deteoriation of passive fire protection material C5-M Structural steel offshore

  13. Examples of corrosion behind PFP Severe corrosion of structural I sections beneath fireproofing Chemical Plant USA (C5-I)

  14. Examples of corrosion behind PFP Gas pipe-work support structure Structural steel onshore C4 / C5-I

  15. Examples of corrosion behind PFP Process vessel and structural steel offshore Structural steel offshore C5 -M

  16. Examples of corrosion behind PFP LPG Sphere Leg Structural steel onshore C5 - M

  17. 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

  18. 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

  19. 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

  20. 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 • 1990’s • Tried to address weathering aspect • Limited success

  21. 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

  22. UL 1709 Exterior Listing

  23. 168 hours Σ4200 hrs Norsok M501 Revision 5

  24. Norsok M501 Revision 5 - continued

  25. 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

  26. 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

  27. 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

  28. 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)

  29. 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

  30. 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)

  31. 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

  32. Questions Ian.Bradley@AkzoNobel.com

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