An analysis of the ductile fracture arrest in the first Alliance burst test has been conducted to examine the arrest of a ductile fracture in the presence of a rich gas, high stress level (80% SMYS), and high pressure (1740 psig, 12 MPa). The analysis used a three dimensional finite element analysis of a ductile fracture propagating in a buried gas transmission pipe to determine the crack tip opening angle (CTOA). The CTOA was calculated as a function of the fracture speed.
The critical CTOA was determined from Charpy V-notch and Drop Weight Tear Test specimens. The results indicate that in this instance the CTOA accurately assessed the fracture behavior observed in the burst test.