Types S31600 and S31254 stainless steel heat exchanger plates have suffered crevice corrosion and stress corrosion cracking under gaskets in rich amine service in a sour gas plant. The gasket material, ethylene-propylene-diene monomer (EPDM), has been used successfully for many years at other sour gas plants. Laboratory testing has duplicated the corrosion observed and shown that th mechanism is synergistic sulfide-halide attack. The use of a bromine plus
chlorine-activated curing system for the EPDM rubber gaskets provided the necessary halides. Laboratory testing identifie some nickel-based superalloys which were resistant to this corrosion and also demonstrated that essentially halogen-free, peroxide-cured EPDM gaskets do not cause attack of S31600 or S31254. The heat exchanger packs were replaced with S31600 plates and peroxide-cured EPDM gaskets having specifed total halogen concentration of 200 ppm maximum. Field operating experience has been excellent.
Keywords: stainless steel, heat exchanger plates, EPDM gaskets, sour gas plant, rich amine, crevic corrosion, stress corrosion cracking, sultlde-halide attack, rubber curing system