Corrosion Under Insulation
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This document summarizes a presentation on corrosion under insulation (CUI) and coatings for mitigating CUI. It discusses how CUI occurs due to moisture ingress under insulation and temperature cycling. Several coating types are described that can provide barrier protection for steel under insulation, including epoxy phenolic, silicone acrylic, thermal spray aluminum, titanium modified inorganic copolymers, and inert multipolymeric matrix paints. Test methods for evaluating CUI coatings like cyclic pipe tests and CUI chambers are also summarized. Real-world case studies show how some coatings have performed well under long-term cyclic service conditions.
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Corrosion Under Insulation
- 1. From Trauma to Transcendence: CUI and Coatings of Choice Dr. Mike O’Donoghue – AkzoNobel Vijay Datta, MS – AkzoNobel SSPC Webinar, October 25th , 2016
- 2. • Introduction • Causes of CUI and Mitigation of CUI • CUI Coating Solutions • Coating Testing Agenda Protective Coatings Unless otherwise agreed in writing by AkzoNobel, all products supplied together with all technical service, information, advice and recommendations given are subject to our standard terms and conditions of sale which are available on request. Any information given here is for guidance only and is provided without any representation or warranty of any kind, express or otherwise. Further, AkzoNobel accepts no control or liability for the appropriateness of any product or the surface, structure or design to which our products are applied or the application process itself. You should seek independent expert advice as to the appropriateness of a particular design or structure for use of our products. We also strongly recommend that independent testing and/or assessment is carried out prior to the application of any product to determine suitability for use.
- 3. Corrosion Cost Comparison Annual Global Cost of Corrosion: > US$ 2.5 Trillion (3.4% of a country’s GDP) Annual Cost of US Natural Disasters : > $19 Billion Corrosion costs the US Economy > 50 times as much as all the natural disasters Courtesy: NACE International IMPACT Study, 2016 G2MT Laboratories 2014 Pierre Crevolin, NACE Western Regional Conference 2005
- 4. Corrosion rates of carbon steel can be significant if operating at high temperatures and subject to temperature cycling, particularly when thermally insulated “… approximately 35% of incidences of corrosion failures, or near failures were caused as a result of corrosion under insulation …” (This statement follows a 2 year survey of plant failures at a major US petrochemical complex) Corrosion Under Insulation (CUI) – Costs Billions
- 7. Corrosion of steel under thermal insulation due to the presence of moisture, oxygen, and other corrodents Known since 1950’s High interest since 1983 NACE SP0198 - 2010 & EFC 55 Carbon Steel - 4C to 175C Stainless Steel 50C to 175C Overview of CUI
- 8. CUI Corrosion under ‘wet’ thermal insulation - aggressive CUI is up to 20x faster than atmospheric corrosion (1.5 – 3.0 mm/year) Insulated high temperature steelwork requires protection against CUI which is a threat during construction, shutdown and intermittent use of equipment
- 9. Why is there is a problem? • No insulation is 100% waterproof • The corrosion rate under wet insulation can be up to 20 times greater than the rate at ambient operating conditions • Corrosion is hidden • Nothing runs above 212o F forever • Equipment temperatures cycle • Inspection can be limited and costly • Reluctance to shut down unit • Budgetary concerns
- 10. Implications of CUI Critical Steel Temperature Ranges for corrosion: • C-Steel 25F → 302F (Greatest Risk of Corrosion) • S-Steel 122F→ 302F (Greatest Risk of E.S.C.C. ) The highest corrosion rates are normally experienced in operational conditions between 140F to 250F Moisture ingress into broken or compromised insulation can occur from 32F to 302F
- 11. HEATING COOLING Coating Insulation Steel Coating must provide excellent corrosion protection to insulated steelwork which experiences thermal cycling conditions Moisture movement Thermal Cycling – The vehicle for CUI
- 12. Corrosion at Elevated Temperatures • For corrosion to occur three key elements MUST be present • Water is not present in equipment where continuous operating temperatures above 248F exist • However, during shut down or cyclic temperature operations, rapid cooling can lead to condensation, & subsequent corrosion problems • Repeated cycling increases both corrosion rates, and potential for failure of coating systems Air SteelWater Corrosion
- 13. CUI Dynamics Moisture Under Insulation C U I Maintenance Requirements Project Budget Inspection Cyclic Temperatures Soluble Chlorides
- 14. Thermal Resistance Anticorrosive Properties (Cartoon Figs Courtesy Hexion) CUI Coating Solutions - Balancing…
- 15. Metallic, Organic and Inorganic Solutions to CUI?
- 16. • Flame spray, arc spray, plasma spray techniques • Aluminum Spray Alloy 1100 or 1350 • SSPC-SP5/NACE 1/Sa3 (3-4 mils) • Temp Resistance to ca 595C • Life cycle costs are low • Process slow, installation costs are relatively high vs coating spray application, DFT issues, needs to form oxides • Galvanic protection – sacrificial system • Susceptible to corrosion by wet salts above 80C • Porosity • Seal coat or no-sealer coat? Wire Compressed Atomising Air Oxygen Fuel Gas Mixture Coating Spray stream of molten atomised particles Substrate Nozzle Air Cap CUI Solutions - Thermal Spray Aluminum
- 17. Organic – Epoxy Organic - Phenolic/ Novolac Epoxy Inorganic – Conventional Thin Film Silicones, TSA Inorganic - Inorganic copolymer, TMIC Inorganic - Zinc Silicates 650C Technology CUI Solutions – Transcendence Road 125C 220C 400C 600C Temperature Higher bond strengths of Inorganic Si-O bond (452 KJ mol-1 ) vs Organic C-C bond (350 KJ mol-1 ) confers thermal stability
- 18. The Zinc Silicate Question (photo courtesy Peter Bock)
- 19. NACE SP 0198-2010SP0 198-2010 Typical Protective Coating Systems for Carbon Steels Under Thermal Insulation and Fireproofing – Courtesy Art MacKinnon, PPG Hi-Temp Coatings System Number Temperature Range (A)(B) Surface Preparation Surface Profile, µm (mil) (c) Prime Coat, µm (mil) (D) Finish Coat, µm (mil) (D) CS-1, CS-2, CS-3 Epoxy, Fusion Bonded Epoxy, Epoxy Phenolic minus 110° to 302°F [minus 45° to 150°C] CS-4 -45° to 205°C (-50 to 400°F) NACE No. 2 / SSPC-SP 10 50-75 (2-3) Epoxy novolac or silicone hybrid, 100-200 (4-8) Epoxy novolac or silicone hybrid, 100-200 (4-8) CS-5 -45° to 595°C (-50 to 1100°F) NACE No. 1 / SSPC-SP 515 50-100 (2-4) TSA, 250-375 (10-15) with minimum of 99% aluminum Optional: Sealer with either a thinned epoxy- based or silicone coating (depending on maximum service temperature) at approximately 40 (1.5) thickness CS-6 -45° to 650°C (-50 to 1200°F) NACE No. 2 / SSPC-SP 10 40-65 (1.5-2.5) Inorganic coplymer or coatings with an inert multipolymeric matrix, 100-150 (4-6) Inorganic coplymer or coatings with an inert multipolymeric matrix, 100-150 (4-6) CS-7 Petroleum wax primer; ambient to 140°F [60°C] CS-8 Shop primers and topcoats for inorganic zinc (IOZ) minus 110° to 750°F [minus 45° to 400°C] Novolac, phenolic, inorganic copolymer and inert polymeric matrix
- 20. Coatings for CUI Mitigation Epoxy Phenolic Silicone Acrylic TMIC Silicone IMMP Binder: Epoxy Phenolic High Temperature Silicone Acrylic Heat Resistant Cold Spray Aluminum High Temperature Silicone IMMP Temperature Ranges: Ambient up to 392F; intermittent surges up to 446F Ambient up to 500F -321F up to 1200F Ambient up to 1004F -321F up to 1202F Typical Systems: 2-coats x 4-6 mils DFT 2-coats x 1.6 mils DFT 2-coats x 4 mils DFT 3-coats x 1 mil DFT 2-coats x 4 mils DFT 1-coat x 1.6 mils DFT over IOZ 500F over OZ 300F 1-coat x 8 mils DFT 2-coats x 1-1.5 mils DFT over IOZ 1-coat x 8 mils DFT Under Insulation: Yes No Yes No Yes Substrate: Carbon Carbon Carbon Carbon Carbon Stainless Stainless Stainless Stainless Stainless IMMP = Inert Multipolymeric Matrix Paint TMIC = Titanium Modified Inorganic Copolymer
- 21. Barrier Protection - Epoxy Phenolic coatings perform well in high temperature aggressive environments because of their very densely cross linked nature Epoxy Polyamine + Crosslink Typical Cross-linked Epoxy Densely Cross-linked Epoxy Phenolic Epoxy Phenolic Polyamine + Crosslink Epoxy Phenolic and Novolacs (CS-4; - 45C to 205C, -50F to 400F)
- 22. • Carboline Thermaline 4001 • Dampney Thurmalox 225HD • Hempel Versiline 56990 • International Interbond UPC 1202 • Jotun Jotatemp 650 • PPG Hi-Temp 1027 • Sherwin Williams Heat-Flex Hi –Temp 1200 Barrier Protection Playing Field (CS-6; - 45C to 650C, - 50F to 1200F) Examples:
- 23. MIO Pigmented IMMP for CUI Mitigation SEM Image after 4000 C 200X Magnification MIO Platelets Barrier Protection
- 24. Aluminum Flake Pigmented TMIC for CUI Mitigation SEM Image after 4000 C 1000X Magnification Interlacing aluminum platelets, intact Barrier Protection
- 25. 25Marine & Protective Coatings CUI Coatings - More Balancing Damage own to metal Harder Coating “Bruising” effect only Softer Coating
- 26. International Paints Cyclic Pipe Tests Courtesy O’Donoghue and Datta, International Paint CCCPT CUI Cyclic Corrosion Pipe Test
- 27. 100C 600C Heated to 600C 8 hours Naturally cooled 16 hours Repeated x 30 Temperature°C Time 600C Diameter = 6 cm Length = 60 cm 1 litre 1% NaCl twice/day Courtesy O’Donoghue and Datta, International Paint` CUI Cyclic Pipe Tests cyclic temperatures to mimic end user processes
- 28. CCCPT procedure run with temperature probes to measure temperatures across the pipe Monitoring / Verifying the Coating Temperature
- 29. TSA and IMMP & TMIC Coatings on Carbon Steel IMMP TMIC IMMP TSA
- 30. 70C-100C 100C-165C 165C-215C 215C-300C 300C-450C 450C-560C Coatings on Carbon Steel up to 560C IMMP TMIC
- 31. PPG CUI Chamber Test (2008-Present) Courtesy Dik Betzig PPG Hi-Temp Coatings Testing method approved: Shell Oil 2008, Aramco 2010 Method B 350F (177C) 5% NaCl Method B 5% NaCl solution Temperature Control Ambient to 250C
- 32. CUI Chamber Test Cell Courtesy Dik Betzig PPG Hi-Temp Coatings Before Test After 6 Weeks Front View After 6 Weeks Bottom View
- 33. Track Record Cyclic Service Conditions: 260C to 40C
- 38. Publications “When Undercover Agents are Tested to the Limit: Coatings in Action (CIA) and Corrosion Under Insulation” JPCL, May 2014 SSPC Presidential Lecture Series Award in 2013 “When Undercover Agents Can’t Stand the Heat: Coatings in Action (CIA) and the Netherworld of Corrosion Under Insulation” JPCL, February 2012 Outstanding Publication of the Year Award in 2013 “From Trauma to Transcendence: Corrosion Under Insulation” NACE, Northern Area Western Conference, 2010
- 39. Thank You - Questions? www.akzonobel.com/protective Vijay Datta, MS vijay.datta@akzonobel.com Dr. Mike O'Donoghue mike.odonoghue@akzonobel.com
Notas del editor
- Vijay – read and cite Pierre Crevolin (what was G2 MT Vijay?) Vijay – Impact Study States “ By using currently available corrosion control practices, it is commonly estimated that savings of between 15 and 35% could be realized….
- Motiva Delaware City started when sparks from welding on a catwalk fell onto, and then into, a severely corroded sulfuric acid tank, that then ignited and exploded.
- E.S.C.C. = External Stress Corrosion Cracking Stress corrosion cracking (SCC) is the growth of cracks in a corrosive environment. It can lead to unexpected sudden failure of normally ductile metals subjected to a tensile stress, especially at elevated temperature in the case of metals. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a small number of chemical environments. The chemical environment that causes SCC for a given alloy is often one which is only mildly corrosive to the metal otherwise.
- Mike
- A long and accomplished history of success Offshore platforms and bridges For CUI – the jury is out – TSA can deteriorate under wet insulation Sacrificial system International Standards for application and composition High degree of Surface prep Porous, some interconnectivity of voids, open structure We studied sealing: porosity reduced, see Ole Knudsen
- vijay
- 302F = 150C 392F = 200C 446F = 230C 500F = 260C 300F = 150C -321F = -197.88C 752F = 400C -265F = -165C 1050F = 565.55C 1004F = 540C 1202F = 650C
- VJ explains
- Vijay explains This is TMIC – Titanium Modified Inorganic Copolymer Q. VJ to M: How does real life experience of this technology compare with the laboratory tests, is there any correlation? You have done lots of independent lab testing on this technology, tell us about that?
- VJ explains