Experimental study on the temperature dependence of gaseous hydrogen permeation and hydrogen embrittlement susceptibility of X52 pipeline steel

For the hydrogen-blended natural gas pipelines, operating temperature has an impact on the interaction between hydrogen and pipeline steel, thus influencing the hydrogen embrittlement (HE) risk of the pipelines. The effects of temperature on the hydrogen diffusion and HE behaviors of X52 pipeline steel were studied through a combination of in-situ gaseous hydrogen permeation experiments, SSRT tests, fracture morphology analysis and TDS tests. The temperature dependences of hydrogen permeation kinetics and HE susceptibility were established. The results show that within the temperature range from 20 degrees C to 60 degrees C, the hydrogen diffusivity increased significantly with rising temperature and satisfied the Arrhenius relationship. The subsurface hydrogen concentration reduced with temperature, which was due to the fact that the hydrogen diffusion increased faster than hydrogen absorption during the experimental temperature range. In addition, the HE index calculated in the SSRT tests and fracture morphologies indicate that the HE sensitivity of X52 steel increased with temperature, which was related to the higher amount of hydrogen trapped in the steel at 60 degrees C from the TDS analysis. This study can provide reference for the material safety evaluation under various operating temperatures of the hydrogen-blended natural gas pipelines.