Numerical results of the J-integral are obtained by elastic-plastic fi
nite element analysis for an external, axial crack in an internally pr
essurized cylinder whose material exhibits a large yield plateau in th
e true stress-strain curve. Comparisons are made with the EPRI J-estim
ation values by three different Ramberg-Osgood approximations. The yie
lding and hardening behaviours in the vicinity of the crack tip under
internal pressure are analysed by means of finite element results. Fin
ally, the applicability of the EPRI procedure for the material is disc
ussed.