Abstract
Abstract The present paper describes a failure investigation of a double disc valve stem made of duplex stainless steel 329 (UNS S32900). The valve stem which operated in moist H2S environment at 128 °C in a heavy water plant had undergone cracking during operation. The microstructure of the stem material showed precipitates of σ-phase at ferrite/austenite boundaries and elongated oxide inclusions. The formation of σ-phase had occurred during the manufacturing stage of the stem. The crack propagation was more favourable in the ferrite phase and along the ferrite/austenite boundaries where precipitates of σ-phase were formed. It was concluded that the valve stem failed by sulphide stress cracking due to hydrogen embrittlement of ferrite phase. Recommendations to avoid such failures are also suggested.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
