Simulation of crack growth during hydrostatic testing of pipeline steel in near-neutral pH environment

The objective of this investigation was to understand the role of crack dimension, hydrogen, room-temperature creep and loading procedure on crack growth during hydrostatic testing of pipeline steels in near-neutral pH aqueous soil environments. Crack growth was found during hydrotesting, but was not linearly related to the stress intensity factor at the crack tip. Crack growth is mainly driven through the internal-hydrogen-assisted-cracking mechanism, instead of the hydrogen-environmental-assisted-cracking mechanism. Excessive plastic deformation induced by room-temperature creep prior to hydrotesting reduces crack advance during hydrotesting. Lower loading rate generally induces larger crack growth by hydrostatic loading. More crack growth occurs during loading in high stress regime.

Research highlights
► The first detailed study on crack growth behavior of pipeline steel during hydrostatic testing in near-neutral pH environment.
► No linear-relationship exists between crack advance and stress intensity factor at the crack tip.
► Crack growth is mainly driven through the internal-hydrogen-assisted cracking mechanism.
► Room temperature creep prior to hydrostatic testing can reduce the crack growth during hydrostatic loading.
► Lower loading rate generally induces larger crack growth by hydrostatic loading. More crack growth occurs during loading in the high stress regime.