Numerical simulation-based pinhole leakage characteristics and hazard boundaries of buried natural gas risers

Corrosion, ageing, and other failure factors pose safety hazards to underground natural gas pipelines. In actual rescue operations, in addition to paying attention to leakage accidents in horizontal pipelines, the severity of vertical pipelines cannot be ignored. This article first selected the buried riser model and simulated the leakage and diffusion characteristics of leaked gas in soil through numerical simulation. By comparing and analyzing the hazard boundaries of vertical and horizontal pipelines, we define the hazard time, farthest hazard distance, and ground hazard range to determine the hazard boundary. The results indicate that soil type seriously affects the danger boundary of buried natural gas pipelines, with sand having the most significant danger boundary and clay having the most minor danger boundary. The influence of leakage hole size and pressure is significant, while the influence of leakage direction and pipeline burial depth is relatively small. When the leakage direction is the same, the danger boundary does not change much; When the leakage direction is different, the dangerous boundary changes even more. Therefore, the leakage of the riser is more concealed and dangerous. This work can provide a reference for leak location and emergency response.