Sulphide stress corrosion cracking of multiple welding repairs of girth welds in line pipe

Abstract

The susceptibility to sulphide stress corrosion cracking (SSCC) of four conditions of shielded metal arc welding repairs and one as welded specimen of the girth weld in seamless API X-52 microalloyed steel pipe were evaluated using slow strain rate tests. The slow strain rate tests were performed in air and in a NACE solution saturated with H2S both at room temperature to a constant elongation rate of 25·4 × 10–6 mm s–1. The SSCC susceptibility was evaluated in function of the reduction in area ratio and elongation ratio and also was manifested as a decrease in the mechanical properties. According to this consideration it is clear that all the weldments exhibit a great susceptibility to SSCC. After failure, the fracture surfaces were observed in the scanning electron microscope. The metallographic observations of the fractured specimens showed that the most susceptible area to SSCC was the intercritical heat affected zone.