Investigation on the mechanical degradation of a steel line pipe due to hydrogen ingress during exposure to a simulated sour environment

The loss of ductility of a longitudinally welded steel pipe, brought about by hydrogen ingress during exposure to simulated sour environments, was investigated. The material was found to be very prone to hydrogen induced cracking (HIC). The presence of hydrogen-induced cracks were not necessarily detrimental to the ductility as demonstrated by ex-situ straining. It was concluded that mobile lattice hydrogen was responsible for ductile loss, while trapped hydrogen was responsible for HIC.