FTA and Safety Monitoring Priorities for Third-Party Damage to Natural Gas Pipelines

With the continuous expansion of natural gas pipeline networks, operational experience identifies third-party damage as the leading external cause of pipeline failure. To identify initial risks and clarify the accident causal chain, a Fault Tree Analysis (FTA) model for third-party damage is constructed, encompassing 22 basic events that systematically represent three risk categories: unsafe human acts, unsafe equipment conditions, and management deficiencies. Boolean algebra simplification yields 19 minimal cut sets and 2 minimal path sets. Structural importance ranking identifies 12 first-order cut sets as single-point failure risks requiring “zero tolerance” control; 6 second-order cut set events require paired failures to constitute risk, suggesting a dual-control mechanism integrating inspection and rectification; 4 fourth-order cut set events require quadruple factor combination to trigger accidents, manageable through integrated preventive measures. Based on these analytical results, a three-tier progressive prevention and control strategy is proposed—event logic bottlenecks, work management modes, and on-site treatment measures—providing scientific basis for precise safety monitoring, differentiated resource allocation, and emergency planning. This approach facilitates systematic reduction of third-party damage risks in natural gas pipelines, preventing catastrophic accidents.