X100管线钢在微生物腐蚀环境下的延性裂纹止裂可靠性研究及失效分析

基于管线钢的环向应力、断裂韧性及腐蚀速率,建立了天然气管线钢在微生物腐蚀环境下延性裂纹止裂可靠性的预测方法,获得不同微生物腐蚀速率对X100管线钢的止裂韧性和止裂可靠性随使用年限增长的变化规律。对X100管线钢延性裂纹扩展失效模式和强度失效模式进行了分析,并基于两种失效模式对X100管线钢的允许使用年限进行了预测,且强度失效所预测的管线钢使用年限要多于延性裂纹扩展失效得出的使用年限,表明X100管线钢的延性裂纹失效风险概率要高于强度失效,在进行安全评估时应优先考虑延性裂纹扩展导致的管线失效模式。

Reliability Study and Failure Analysis of Ductile Crack Arrest of X100 Pipeline Steel in Microbial Corrosion Environment

A model of predicting the probability for the ductile fracture crack arrest within the natural gas pipeline under microbial corrosion environment was proposed as the functions of the circumferential stress, fracture toughness and corrosion rate. The effect of the microbial corrosion rate on the crack arrest toughness and crack arrest probability with the increase of service duration was studied. Both the failure modes of the ductile fracture crack and stress failure in the X100 pipeline steel were analyzed. The service lives of the X100 pipeline steel were also predicted with the two failure modes, and the service life of the X100 pipeline steel predicted from the stress failure mode is longer than that from the ductile fracture crack failure mode. This result proves that the risk probability of the ductile crack failure in X100 pipeline steel is higher than that of the stress failure, and the ductile crack failure should be more concerned during the safety evaluation for the X100 pipeline steel.