The development and validation of a dynamic fracture propagation model for gas transmission pipelines

A fracture control methodology that will prevent the possibility of long-running crack propagation, based on the crack-tip opening angle (CTOA) is outlined here. Two aspects are considered: (1) the calculation of the maximum CTOA for a given geometry and loading and (2) the determination of the critical material property for fracture, (CTOA)_c. The vehicle for CTOA calculations was a fluid/structure/fracture interaction inelastic dynamic computational model for fast long-running fracture in pipelines. Validation of the approach used in this analysis was provided through quantitative comparisons with measured full-scale burst test data. A convenient two-specimen drop-weight tear test was used to determine the (CTOA)_c for line pipe steels. The linking of the latter with the quantification of a maximum CTOA for steady-state ductile fracture, using the numerical model, provides the basis for an approach that evaluates the conditions needed to ensure crack arrest.