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Corrosion under thermal insulations namely CUI (Corrosion under insulation) is among the key degradations posing integrity risks to the hydrocarbon processing, chemical, and petrochemical facilities. CUI is reportedly known as the reason behind 40-60% of failures in the piping for the oil refineries. Whereas the small-bore piping (i.e., NPS< 4”) is more prone to this damage mechanism where reportedly where up to 81% of failure result from CUI.
CUI (corrosion under insulation) is among the leading damage mechanisms active in oil refining and hydrocarbon facilities. Reportedly, 10% of the total maintenance budget of a typical refinery is spent on inspecting and fixing CUI damages. The mechanism of CUI is complex and influenced by many factors namely the design of the insulated system, insulation type, ambient conditions, condition of coatings and insulation materials, as well as operating parameters. This study addresses the quantified influence of cyclic temperatures on CUI in comparison with constant temperatures for various insulation designs namely the closed-contacting and contact-free with low-point drainage. It also investigates the CUI behaviors under moisture cycling (i.e., wet-dry conditions) of candidate insulation designs in comparison to a fully wet environment. To simulate this, corrosion rates were determined under Isothermal wet, isothermal wet-dry, cyclic wet, and cyclic wet-dry conditions using weight loss measurement as per applicable ASTM G189-07 standard. The influence of cyclic temperatures and wet-dry conditions were also studied using the linear polarization resistance method in the system with contact-free insulation. The corroded coupons were then characterized using a microscope and surface topography. The wet-dry conditions under both cyclic and constant temperatures caused more corrosion rates than those under wet conditions. Also, cyclic temperatures caused more corrosion rates than constant temperatures under both wet and wet-dry conditions.
Many types of thermal insulation materials are used in oil and gas plant facilities. Recently new materials have been developed to prevent corrosion under insulation (CUI) and even the conventional materials have been improved their properties to provide better protection.When designing a plant measures to prevent CUI are studied when verifying the materials of construction determining the protective coatings systems and selecting thermal insulation and jacketing materials. Measures to prevent CUI should not be considered separately for these but rather together as a total system. Recently though while protective coatings have been studied by users coating manufacturers and independent organizations such as testing laboratories engineering firms and consultants there has been little investigation of the ability of thermal insulation materials themselves to prevent CUI.In this study the ability of various thermal insulation materials to prevent CUI in a simulated severely corrosive environment were examined. The factors influencing CUI prevention or aggravation were identified based on which it was recommended that these factors be considered when selecting thermal insulation materials during the design of a plant. As a summary of this study experiences of design of plants and related other CUI studies effective ideas relating to protective coatings thermal insulation and jacketing materials for preventing CUI will be shared.
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The designer of industrial equipment and piping has three weapons in the fight against corrosionunder insulation (CUI). The first and primary defense against CUI is a high quality, immersiongrade coating. The second is a properly designed and installed weather barrier jacketing. The thirdand, arguably, least understood element is the choice of insulation material. This paper will explorethe ways in which insulation materials influence CUI behavior, presenting results from bothlaboratory and field-testing on seven industrial insulation materials and one composite system.The materials tested were calcium silicate, expanded perlite, cellular glass, mineral wool (bothregular and water-repellent grade), and two types of flexible aerogel blanket material -PyrogelXT and Cryogel Z
Pond investigated pressure vessel tank failures which are causing recurring maintenance of $250,000 per year. This challenging project had limitations of space, operational time pressures/vessel availability requirements, cost and replacement variables. This presentation will chronical problems and discuss best practices of specifications, material selection, surface preparation, and application inspection that would have prevented the aforementioned outcome. This paper discusses the fundamentals of composite coatings, industry accepted design standards for their use, and examples of typical uses for these materials that solve problems in varied industries.