Development of Enhanced C-Mn Pressure Vessel Plates with Advanced Sour Service Resistance - SOHIC Steels

摘要

Wet hydrogen sulfide cracking of pressure vessel steels has been a major concern in petroleum refining as well as in the oil and gas industry since the 1950's. Nowadays, more and more H_2S-containing oil and gas fields are exploited. Hydrogen sulfide is responsible for numerous corrosion phenomena in steels, such as Hydrogen Induced Cracking (HIC), Sulfide Stress Cracking (SSC), and Stress Oriented Hydrogen Induced Cracking (SOHIC). During the last 30 years, pressure vessel steels with improved SSC, and furthermore HIC, resistance have been developed to resist H_2S-induced degradation in upstream and downstream equipment. More recently, attention has been particularly directed on Stress Oriented Hydrogen Induced Cracking experiences in wet H_2S operations. This paper reports the new results obtained on both normalized and quenched and tempered C-Mn pressure vessel and pipe plate steels. SOHIC resistance has been evaluated according to the requirements of NACE MR0175 / ISO 15156 Annex B.4. Results show that only quenched and tempered steels can offer optimized SOHIC resistance thanks to the fine bainitic microstructure provided by the use of adapted heat treatments combined with optimized chemical composition and steel fabrication route.