The method of testing and analysis stress damage of oil-gas pipeline based on hysteresis

Stress concentration is a serious threat to the safety of pipeline. It is great significant to security management of oil-gas pipeline that the stress concentration can be tested and evaluated. The relation model between stress and coercive force is established based on hysteresis of ferromagnetic material. Through tensile test, stress damage critical state parameters are obtained, the parameter ranges corresponding with different stress damage state are obtained. Stress damage state is analyzed and evaluated based on these parameters. The results show that the relation between stress and coercive force is linear. The critical parameters of deformation state are corresponded with stress damage critical state parameters. Under three stress damage states: safety, control and danger, the critical coercive force parameter ranges of X80 steel are obtained though experiment. The correctness and the effectiveness of analysis method for stress damage are validated through application on pipeline.