Service life prediction of pipeline under hydrogen-induced microcrack stress corrosion

Fracture of pipeline usually begins with microcracks, and it is very important to study its formation, distribution, propagation in the service life prediction of pipeline. The evolution model of stress corrosion damage of pipe is analyzed based on the damage mechanics theory. The relationship between the residual life of pipeline and the growth rate of hydrogen microcrack is derived according to energy conservation law and the calculation formula for the expansion of potential energy and kinetic energy. Result shows that crack growth rate is increased with the increase of hydrogen pressure. The effect of H₂S and CO₂ contents(two main corrosion factors) on the residual life of pipeline is analyzed through a case. The results are as follows: (1) the corrosion of pipeline is aggravated when both H₂S and CO₂ exist in the pipeline; (2) the residual life of pipeline will decrease if H₂S and CO₂ contents are increased and the operation pressure and other parameters are constant.