FRACTURE-ANALYSIS OF FULL-SCALE PIPE EXPERIMENTS ON STAINLESS-STEEL FLUX WELDS

The objective of this paper is to verify the ability of current fractu re analysis methods to predict loads and displacements for circumferen tial, through-wall-cracked, stainless steel, flux-welded (i.e. submerg ed-are weld and shielded-metal-are weld) pipes under pure bending. Cra ck initiation and maximum load predictions were made using five differ ent J-estimation schemes, the Net-Section-Collapse analysis, and the A SME Section XI IWB-3640 flaw evaluation criteria. The predicted loads were compared with the observed crack initiation and maximum loads fro m four full-scale pipe fracture experiments involving 152.4 mm (6 in) and 711.2 mm (28 in) nominal diameters at 288 degrees C (550 degrees F ). In some cases, load-displacement relationships predicted by the est imation methods were also compared with the actual test record. The ex periments were conducted under the Degraded Piping and Short Cracks in Piping and Piping Welds Programs. The results show that both LBB.ENG2 and LBB.ENG3 methods, which were previously developed by the authors, provide more accurate predictions than other analysis methods conside red in this study. The comparisons with pipe fracture data also reveal that differences in the weld thickness and procedure between the pipe s and compact tension specimens can provide widely different fracture toughness characteristics and hence, can significantly influence predi ctions of the pipe's load-carrying capacity by the J-estimation method s.