In 1971, the Physical Metallurgy Research Laboratories (PMRL) undertook the assessment of a number of steel transmission line pipes. The pipes were purchased during 1971-1973 and had diameters in the range 30-48 inches (762-1218 cm) and tensile yield strengths in the range 67-84 ksi (462-579 MPa) (see also Tables 1-3). Some of the pipes were trial commercial productions oriented towards use in an Arctic gas transmission pipeline and none had been made for a sour-gas application.
There was no evidence that environmentally induced stress cracking was an important threat to the integrity of Canadian pipelines, but it was decided, as a minor part of the assessment, to perform exploratory tests on the susceptibility of the mill-welded line pipes to sulfide stress cracking (SSC). The choice of a sour test medium was based on the observation that natural gas, although not considered sour, may contain up to 15...
