Hydrostatic testing is one method to confirm the integrity of pipelines containing colonies of stress-corrosion cracks. Although this technique is widely used, a concern of the pipeline industry is the potential for ductile
tearing damage of subcritical flaws. The objectives of the current study were to evaluate the influence of hydrostatic testing on the crack tip morphology and to determine the amount of ductile tearing that may occur for different hydrostatic testing conditions. Stress-corrosion cracks were grown in compact tension specimens of X-65 line-pipe steel in a near-neutral-pH SCC environment. Simulated hydrostatic tests were performed at loads that corresponded to hoop stresses at and above the specified minimum yield strength (SMYS), resulting in applied J-integral values near to and above J(Q). Some specimens ruptured and some did not fail. Crack tip blunting occurred and the tearing extent was small and proportional to the J integral. The electric potential drop (EPD) technique consistently over-estimated the extent of ductile tearing by a factor of 2 to 3. Keywords: hydrostatic test, ductile tearing, stress-corrosion cracking, pipelines, electric potential drop, crack tip blunting, J-integral