scope:

A study of the catastrophic failure during fatigue testing of PVRC Vessel No. 5, of T-1 steel, was conducted. Pertinent details of the fatigue testing procedure are given, and metallurgical and mechanical test results on failure material are discussed. The fabrication and inspection of the vessel conformed to ASME Code Standards and the best commercial practice. The fatigue life of the vessel was adequate but the failure by a fast propagating fracture was unexpected. The investigation disclosed that the materials in PVRC Vessel No. 5 were typical for firebox quality, T-1 steel, and the initiation and propagation of the terminal fracture were primarily associated with weld zones.