Prevention of failures of high strength fasteners in use in offshore and subsea applications

Adequate strength and resistance to corrosion and environmentally assisted cracking are the key elements in selection of fasteners for offshore and subsea systems. Not only proper material selection is of paramount importance but also proper material processing to ensure suitability of fasteners for the intended subsea service environment. This become increasingly evident as the attention of the oil and gas industry shifts to exploring and developing reservoirs in deeper waters where the cost of operation and intervention is very high. This paper examines some of the challenges that face the oil and gas industry with particular emphasis on prevention of failures due to hydrogen embrittlement (HE) under conditions of cathodic protection (CP). Efforts were made to carefully review factors that could play a significant role in HE. These factors include material selection and compatibility with CP, size effect, qualification testing, design criteria and finally applied stress level after assembly.