STP880: Prevention of Chloride Stress Corrosion Cracking Under Insulation

    Sumbry, LC
    Senior chemist, Gulf Research and Development Co., Pittsburgh, PA

    Vegdahl, EJ
    Consultant, Beaverton, OR

    Pages: 13    Published: Jan 1985


    Abstract

    Chloride stress corrosion cracking of stainless steel under insulation can occur because of concentration of chlorides at the metal surface. This paper discusses our company's current recommended practices for controlling this type of corrosion and results of a research program to improve our recommended practices.

    Our current recommended practice for controlling corrosion of stainless steel under insulation is to select insulation materials low in extractable chlorides, jacket or coat insulation to exclude water and chlorides from the environment, and to coat the stainless steel equipment where applicable. Coating stainless steel to prevent contact with chlorides is recommended with some reservation because of generally poor experience in coating stainless steel equipment.

    A research program is being conducted on coatings for stainless steel equipment. A variety of coatings have been evaluated using adhesion and flexibility tests, outdoor exposure, salt fog cabinet, environmental cabinet containing hydrogen sulfide, carbon dioxide, nitrogen dioxide, and wet air, a Weatherometer cabinet, elevated temperature exposure (260 to 500°C), thermal shock tests, and chloride permeability tests. Adhesion to stainless steel is generally fair. For elevated temperature applications, straight silicones are generally superior. Many coatings are adequate for ambient temperature applications if protected from mechanical damage.

    Keywords:

    chlorides, stress corrosion, insulation, jackets, coatings, stainless steels, mechanical bonds, chemical bonds


    Paper ID: STP39166S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP39166S


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