FATIGUE FAILURE OF A ROTATING CHEMICAL VESSEL

This paper describes the fatigue failure of a welded steel vessel in a chemical plant. The process conditions required the vessel to be rota ted continuously at a speed of about two revolutions per minute. To pe rmit this rotation, a pair of trunnion shafts was welded to opposite s ides of the vessel. Each shaft was supported in a self-aligning bearin g. The connection between the shaft and the vessel was strengthened wi th gusset plates which were fixed to both vessel and shaft by fillet w elds. Because of the self-weight of the vessel, each trunnion shaft wa s subjected to an upward reaction force of 13 tonnes applied at the ce ntre-line of the bearing. After 4 1/2 years in service, 75% of the gus set-shaft welds had failed by fatigue. The failure was analysed using the weld fatigue curves given in BS 5400: Part 10: 1980 and remedial m easures were discussed. Copyright (C) 1996 Elsevier Science Ltd.