Fatigue Life Simulation of High‐Pressure Injection‐Production Pipeline Based on nCode DesignLife

To ensure the safe operation of injection‐production pipelines in underground gas storage, this study establishes fatigue simulation models for both straight and elbow sections of the pipeline to address the issue of fatigue failure under cyclic loading. The analysis includes differences in fatigue life and stress distribution between straight pipes and elbows and the effects of internal average pressure, alternating load amplitude, and frequency on their fatigue life. The results indicate that the elbow of the injection‐injection pipeline bears a greater maximum equivalent stress than the straight pipe, has a smaller number of fatigue cycles, and the maximum fatigue damage occurs on the inner wall inside the center of the elbow. As the average pressure, alternating load amplitude and frequency increase, the fatigue life of the injection‐injection pipeline decreases. For example, when the average pressure on the elbow increases from 20 to 45 MPa, the minimum fatigue cycle number decreases from 7.694 × 10 11 to 9.039 × 10 3 cycles. The research results provide a theoretical basis for optimizing the gas storage injection‐production process and preventing fatigue failure of injection‐production pipelines.