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Keywords:

  • cracking (SSC);
  • high strength low alloy (HSLA);
  • hydrogen embrittlement (HE);
  • sulphide stress;
  • welding

The susceptibility of girth welds to sulphide stress cracking (SSC) and hydrogen embrittlement (HE) were evaluated for API grade X80 and X56 steels, both for similar (X80/X80) and dissimilar (X80/X56) joints. Slow strain rate (SSR) and hydrogen permeation tests were performed at room temperature using sodium thiosulphate solutions at different pH levels. The SSR tests showed that the majority of the welded joints studied, though approved by the API 1104 standard's criteria, did in fact suffer a reduction in ductility and showed indications of susceptibility to sulphide stress cracking and to hydrogen embrittlement in the form of secondary longitudinal and internal transverse cracks. This was true regardless the welding process used.