Using autofrettage technology to decrease stresses in a girth welded joint of a high pressure hydrogen tank

• The welding heat input and working pressure have effect on total stresses.
• The uniformity of the stress distribution can be improved by autofrettage process.
• The effect of welding residual stress can be weakened by autofrettage process.

A numerical model of a welded joint of the hydrogen storage tank was built. The stresses caused by inner pressure, welding, and autofrettage were investigated. Numerical results showed that complicated welded residual stresses were generated in the weld central line and heat affect zone, which made the stresses in the welded joint increase and fluctuate. In order to improve the stress distribution, the autofrettage process was used after welding. Comparison of stress distribution with and without autofrettage, showed that the autofrettage process caused stresses in the welded joint of the hydrogen storage tank to be more uniform along the wall, and decreased the influence of welding on the total stresses. Therefore, the safety of a high-pressure hydrogen storage tank is improved by the application of autofrettage.