Hydrogen Induced Stress Cracking (HISC) in Duplex Stainless Steels: DNV-RP-F112, Design of Duplex Stainless Steel Subsea Equipment Exposed to Cathodic Protection

Both 22Cr and 25Cr duplex (ferritic-austenitic) stainless steels have been extensively used for subsea equipment. In general the experience is good but some significant failures have occurred where Hydrogen Induced Stress Cracking (HISC) have been identified as a contributing factor. Because of these failures there was identified a need within the offshore industry for a design guideline treating HISC as a failure mode and reflecting best practice based on today’s knowledge, experience from in-service failures and recent research. The paper starts with a brief review of some of the failures and the main results from the comprehensive test program in the HISC JIP conducted in cooperation between Sintef and DNV. The JIP is supported by several major oil companies, subsea contractors and material suppliers and constitute the main scientific background for the recently issued Recommended Practice, DNV-RP-F112, Design of Duplex Stainless Steel Subsea Equipment Exposed to Cathodic Protection (October 2008).