Several dynamic analysis issues relating to rapid crack propagation (RCP) and arrest in gas piplines were developed recently, and are presented in this paper. This is based on a fluid/structure/fracture interaction package, PFRAC. Some developments have been implemented into this finite element code to simulate the behavior of the fractured pipes. The criteria for crack initiation, propagation and arrest have been discussed. As the crack propagates along the pipeline, the gas pressure decompression ahead of the crack tip and an efficiency of a linear decay behind the crack have been used in the computation. For the calculation of crack driving force G, the numerical approaches using the nodal force release and energy balance methods are described. This paper also presents a novel analysis methodology that has been developed to investigate the suitability of crack arrestors. Several numerical results for the cracked steel pipes with arrestors are presented along with comparisons with pipes that do not have arrestors.