复杂介质环境下承压设备主导损伤机制的判定与失效可能性分析

2003年以来我们按美国石油协会API 581,API 571等标准,在中国对承压设备开展了大量的风险评估技术研究,掌握了全国近80家大型炼油厂、化工厂及化肥厂的全部装置种类的在用承压设备的风险分布情况,形成了符合中国国情的典型石化装置的失效树及基于风险检验的指导技术文件。但在风险评估实施过程中发现,很多石化装置承压设备因腐蚀介质的多样性、影响因素的复杂性,在实际运行中存在着多种失效模式、失效机理的相互作用,这是现有的API 581标准所没有考虑到的,如果不能确定承压设备在实际服役环境中可能存在的主导失效模式和失效机理及次要机制的影响因素,得到的风险评估分析结果往往与实际情况存在较大差距。在石化承压设备失效事故调查分析、风险评估与试验研究的基础上,就石化工业若干典型复杂介质环境下承压设备多种失效机制共同作用时主导机制的判定方法与次要机制的影响规律开展了研究,针对API 581风险评价中失效可能性计算方法提出了改进建议。

Analysis Method of Failure Likelihood on Pressure Equipment with Combined Action of Multi-Failure Mechanism

Since 2003, Hefei General Machinery Research Institute has conducted many risk based in- spections （RBI） and analysis in China following standards of API 581, API 571 etc. So far, the risk dis- tributions of in - service pressure equipments have been recognized, including their major failure modes, failure mechanisms, failure likelihoods and failure consequence, and the involved pressure equipments cover all kinds of units of about 80 large - scale oil refinery plants, chemical plants and chemical fertilizer plants. Thus, the corresponding failure trees of typical units and technical guide documents of RBI have been formed, which are basically suited to Chinese situation. However, it is found that combined actions of multi - failure modes and mechanisms resulting from the diversity of corrosive mediums and the com- plexity of influencing factors do occur in petrochemical pressure equipments during their actual operating processes. Unfortunately, these effects are not considered by the current API 581. In this case, if the dominated failure mechanisms and the effects of minor mechanisms cannot be recognized effectively, their may be a great difference between assessing results and the actual situation, which will definitely result in unreasonable analysis of their remaining life and inspecting interval. In this paper, surveys of failure ac- cidents, RBI analysis and experimental investigation of pressure equipments in some typical environments of complex mediums were conducted in order to gain the corresponding determination methods of dominant failure mechanism and to clarify the influencing laws of minor mechanisms. Based on this, some sugges- tions on failure likelihood calculating methods of API 581 are given.