Materials Performance

SEP 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

Issue link:

Contents of this Issue


Page 92 of 128

34 SEPTEMBER 2018 W W W.MATERIALSPERFORMANCE.COM COATINGS & LININGS ESSENTIALS THICKNESS MEASUREMENT OF PROTECTIVE COATINGS Coating Thickness Material Analysis Microhardness Material Testing (860)683-0781 Robust, fast and reliable For ships, bridges, off-shore plat- forms, pipelines and structures Measures in accordance with SSPC-PA2, IMO-PSPC and others From basic "readings only" to stats and detailed inspection plans Surface Profile Measurement Easy and affordable ▪ ▪ ▪ ▪ ▪ ▪ Accurate and precise measurement of coating thick- ness with the Fischer FMP Series A third-generation polysiloxane coating is shop-applied to equipment prior to transport and installation. Photo courtesy of James Reynolds and Peter Bock. Mitigating Corrosion Under Insulation with Polysiloxane Coatings Corrosion under insulation (CUI) is a severe form of localized external corrosion that attacks the surface of very hot or very cold steel equipment insulated for thermal pro- tection, energy conservation, or process stabilization. Corrosion occurs when the insulation absorbs moisture that, in turn, wets the steel surface in the presence of oxygen. Attempts to prevent water from entering insulated systems, however, are not sufficiently reliable to prevent CUI, so protective coatings are recognized and accepted as a highly effective method of protecting insulated carbon steel and aus- tenitic and duplex stainless steel surfaces from CUI. During the Oil and Gas Coating Tech- nology symposium at CORRROSION 2018 in Phoenix, Arizona, USA, a presentation by NACE International members James Reynolds and Peter Bock with Performance Polymers (Amsterdam, e Netherlands) discussed CUI and the advantages of third-generation polysiloxane coatings for mitigating it. Insulation on equipment typically includes a top layer of cladding that pro- vides an additional level of protection against moisture and chemical ingress from the environment. In practice, Reynolds and Bock note, the cladding system is not com- pletely sealed from the atmospheric ele- ments, and rain, deluge water, or steam are often able to penetrate the system through access points in the cladding material— generally it is a challenge to create a water- tight system on complex structures. Once water has penetrated the system via breaks, seams, gaps, unsealed valve sections, etc., it is absorbed by the insulation and causes saturation that promotes corrosion of the steel. Potential contaminants such as acid and leaching chemicals (chlorides/sulfides) can form acidic compounds in insulation systems that accelerate the corrosion rate. According to Reynolds and Bock, care- ful materials selection is vital for providing protection in aggressive environments where CUI could be a threat. Requirements for coatings under insulation include corro- sion and chemical resistance, when

Articles in this issue

Links on this page

Archives of this issue

view archives of Materials Performance - SEP 2018