The appearance of new pipe materials has revived interest in the modelling of rapid crack propagation (RCP) along fluid-pressurized plastic pipelines. The correlation of results from two International Standard RCP test methods—one full-scale and partially simulating installation and service conditions, the other lab-scale—remains imperfectly understood. There is no standard method for measuring the dynamic fracture toughness of the pipe material, and models relating toughness to pipe fracture pressure have not gained widespread use. This paper demonstrates an adaptable, extendable, analytically transpar- ent model which accounts for all major influences including residual stress in the pipe wall, constraint from surrounding backfill and partial substitution of the pressurizing gas by water.