Stresses in a pipeline affected by hydrogen

A model is suggested which allows one to describe the influence of hydrogen on the stresses in structural materials. The 2-D problem of plane elasticity was solved on the example of a hollow pipe under internal pressure. Analysis of the stress distribution in the pipe suggests that the radial stress is not considerably affected by hydrogen since the radial stresses are compressive, whereas the hydrogen moves to the domains of tensile stresses. The effect of the hydrogen on the hoop stress is essential, namely the effect of the hydrogen presence (difference between the stresses in the hydrogen-affected material and virgin material) is comparable with and even exceeds the original hoop stress. This effect is especially considerable in the neighbourhood of loading. This effect is often encountered during the exploitation of gas and oil pipelines since the transported medium is full of hydrogen. The hoop stress is tensile which results in an essential influence of the hydrogen on the stress field. Despite the fact that the hydrogen-affected material remains isotropic, the field of stresses demonstrates anisotropic effects of influence of the hydrogen on stresses.