Sulfide stress cracking tests were conducted on welded nickel steels, carbon steels and stainless steel in NACE solution, simulated syngas and simulated sour methanol environments. All nickel steels and carbon steels failed the NACE test at low stress levels; the stainless steels showed no failures. In the simulated syngas and sour methanol environments, only the material from the failed heat exchanger showed environmental cracking during the month long exposure. The sour methanol environment appeared to be somewhat more severe than the syngas environment, but both simulated service environments were considerably less severe than the NACE solution with regard to the promotion of sulfide stress cracking.
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