Effect of Helix Angle on Hydrogen Diffusion of Spiral Weld Pipe

Abstract

This paper presents a study of hydrogen diffusion for a spiral weld pipe considering the effect of weld residual stress. The results show that the hydrogen mainly gathers at heat-affected zone (HAZ). HAZ is the weakest zone where hydrogen-induced cracking (HIC) occurs. The effect of helix angle on the hydrogen diffusion is also discussed. It shows that different helix angles generate different hydrogen concentrations. As the helix angle increases, both the hydrogen concentration and residual stresses decrease. As the helix angle increases from 40 deg to 50 deg, the equivalent pressure stresses reduce a little, resulting in the change of hydrogen concentration being small. The smaller the helix angle is, the larger the diffusion rate is. The most suitable helix angle should be optimized at 40–50 deg.