Hydrogen permeation in high strength steel under load in aqueous environment

Abstract

The hydrogen assisted cracking problem is one of the major causes of the failure occurring in the high strength steel structures used in various industries. In aqueous environment, hydrogen is generated by the hydrogen reduction reaction on the steel surface. With depletion of the high quality resources in oil and gas industry, the hydrogen assisted cracking problem becomes severe in sour environment, which contains high amount of H2S. Understanding on the hydrogen permeation behaviour is crucial to deal properly with the hydrogen related problems since they are primarily determined by the hydrogen uptake and transport in the steel. The Devanathan–Stachurski method is widely used to evaluate electrochemically the hydrogen permeation behaviour. This method has been successfully used for the steel with no load. Under loading condition, this electrochemical test method has been modified to accommodate the externally applied load. However, the data require careful examination to validate the technical importance because of the stability and homogeneity of palladium layer coated on the steel surface under load. In this paper, the hydrogen permeation test method under loading condition will be reviewed for the high strength steels used in oil and gas industry. The factors affecting the hydrogen permeation in the high strength steel will be discussed in terms of the applied stress level and the sulphide film forming on the steel surface in sour environment.