The battle in opposition to corrosion beneath insulation

The hidden risks of corrosion beneath insulation (CUI) span the oil and fuel trade from upstream operations to midstream infrastructure and downstream functions, together with the manufacturing of LNG. CUI is a extreme type of localised corrosion that happens when water, inorganic salts, and different contaminants develop into trapped beneath insulation overlaying pipes, valves, tanks, and different belongings, resulting in the formation of corrosion cells which can be hidden from view and might unfold unnoticed.

In oil and fuel operations, elevated course of temperatures could speed up corrosion charges, resulting in pitting and metallic loss that will trigger leaks and probably catastrophic failures, with the potential to hurt personnel and, in excessive circumstances, trigger the lack of life. But, in LNG operations, chilly/cryogenic temperatures may contribute to elevated CUI dangers. An ideal recipe for corrosion – moisture, oxygen, and chlorides – exists in each temperature situations, however moisture from condensation could be particularly prevalent beneath insulation in cryogenic LNG operations as a result of excessive temperature differentials with ambient air. Research present that moisture causes 85% of insulation system failures in LNG operations. On the identical time, some LNG functions additionally function at excessive warmth, compounding CUI threats throughout complete services.

As a result of cryogenic temperatures are required for quite a few LNG refinery functions, most belongings are produced from stainless-steel somewhat than the carbon metal that’s generally utilized in different oil and fuel refining operations. Stainless-steel gives added power, hardness, and corrosion resistance, serving to LNG services higher shield their manufacturing belongings, together with at very low temperatures. Nevertheless, stainless-steel continues to be vulnerable to corrosion, with chloride stress corrosion cracking (CSCC) being particularly virulent when chlorides from salts are involved with the metallic, whether or not it’s uncovered or lined with insulation. Such CSCC causes tiny floor cracks to develop in stainless-steel, weakening its construction. These cracks could develop into so pervasive that there may very well be potential for fuel leaks to develop and explosions to happen.

Given the corrosive threats related to insulated belongings utilized in LNG manufacturing, facility operators are greatest served by overlaying belongings with protecting coatings that create a barrier between the metallic substrate under and the chlorides, moisture, and different exposures on the floor. Such coatings ought to be thought of an integral a part of a strong insulation system, as they assist to mitigate the corrosion course of and allow belongings to function longer earlier than requiring upkeep. Nonetheless, a defective insulation system could result in corrosion happening and might put an asset out of fee prematurely.

Conventional natural coatings in CUI service vary from solely 5 – 13 years earlier than services must proceed with expensive inspection and repainting actions. Nevertheless, extra superior coating applied sciences are being formulated to correctly handle typical coating failure mechanisms, providing improved efficiency and thereby extending the lifetime of coated belongings. These formulations are engineered to raised stand up to the various exposures belongings could face earlier than and after they’re insulated, together with elevated and intensely low operational temperatures, publicity to chlorides earlier than and through service, tough dealing with throughout transport, outside storage previous to set up, and excessive moisture circumstances from humidity and condensation. Not solely are a few of these new liquid coatings performing higher than conventional CUI coatings, however they’re additionally quicker, simpler, and extra economical to use in comparison with thermal sprayed aluminium (TSA), which is usually utilized in LNG functions.

LNG manufacturing environments are ripe for CUI

LNG services function at approximate temperatures as little as -162°C (-260°F) and require an efficient thermal insulation system on belongings to stop them from extreme warmth acquire and to keep up these temperatures to make sure efficient and secure operation.
The necessity to higher handle CUI in LNG refining functions is urgent. The world is in a grip of geopolitical turmoil and subsequently international LNG demand is rising, with quite a few tasks deliberate to satisfy rising wants. As current services broaden and new ones are constructed, LNG operators will want confirmed, cost-effective CUI-mitigation options that enhance the protection and long-term productiveness of their services.

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