A Plastic Fracture Mechanics Prediction of Fracture Instability in a Circumferentially Cracked Pipe in Bending—Part II: Experimental Verification on a Type 304 Stainless Steel Pipe

Abstract

The possibility of a pipe fracture emanating from a stress corrosion crack in the heat-affected zones of girth-welds in Type 304 stainless steel pipes was investigated. The J-resistance curve—tearing modulus parameter for the prediction of crack initiation, stable growth and fracture instability—was employed. To evaluate the analysis, a pipe fracture experiment was performed using a spring-loaded four-point bending system that simulated an 8.8-m (29-ft) long section of unsupported 102-mm- (4-in-) dia pipe. An initial through-wall crack of length equal to 104 mm (4.1 in.) was used. Fracture instability was predicted to occur between 15.2 and 22.1 mm (0.60 and 0.87 in.) of stable crack growth at each tip. In the actual experiment, the onset of fracture instability occurred beyond maximum load at an average stable crack growth of 11.7 to 19 mm (0.463 to 0.750 in.) at each tip.