Prediction of failure behavior of a welded pressure vessel containing flaws during a hydrogen-charged burst test

An industry-government collaborative program was carried out with an aim to promoting the acceptance of fracture mechanics-based fitness-for-service a ssessment methodology for a service-damaged pressure vessel. A collaborativ e round robin exercise was carried out to predict the fracture behavior of a vessel containing hydrogen damage, fabrication-related lack-of-fusion def ects, an ar artificially induced fatigue crack, and a localized thinned are a. The fracture assessment procedures used include the U.S. ASME Material P roperty Council's PREFIS Program based on the British Standard (BS) Publish ed Document (PD) 6493, ASME Section XI and The Central Electricity Generati ng Board (CEGB) R6 approach, The Welding Institute (TWI) CRACKWISE program (based on BS PD6493 Level 2 approach), a variant of the R6 approach, J-tear ing instability approaches, various J-estimation schemes, LEFM approach, an d simplified stress analysis. Assessments were compared with the results ob tained from a hydrogen-charged burst rest of the vessel. Predictions, based on the J-tearing approach, compared well with the actual burst test result s. Actual burst pressure was about five times the operating pressure.