Abstract
In the oil and gas industry, the major standard for material selection today is ANSI(1)/NACE(2) (now AMMP(3)) MR0175/ISO(4) 15156 Parts 1-3. This standard deal extensively with environmental cracking and its mitigation under exposure to sour production environments containing H2S, CO2, chlorides, and sulfur. Unfortunately, it does not include material requirements for resistance to environmental cracking under variable subsea applications and conditions that may involve exposure to seawater with or without cathodic protection (CP). Also, ISO 21457 and several other standards identify the corrosion mechanisms and parameters for evaluation when performing selection of materials for pipelines, piping and equipment related to hydrocarbon production, transport and processing, including utility and injection systems; however, they do not address in detail aspects of environmental cracking that can be associated with use of CP in subsea operations. This lack of attention in industry standards is somewhat surprising since exposure of materials to subsea conditions with cathodic protection and the potential for environmental cracking has been documented in the literature for over 50 years. Furthermore, there have been several component failures in high strength materials and recent near-miss, in-service incidents in drill-through equipment bolting/fasteners/studs operating subsea under cathodic protection. This paper comments on the member-driven standardization activities that have recently been initiated through AMPP to define hydrogen stress cracking (HSC) resistant metallic materials for subsea service with cathodic protection, the historical relationship to a material requirement standard – MR0175/ISO15156, and a recent review of published HSC literature and related standards that can support the current standardization efforts for HSC-resistant metallic materials in subsea CP service.
