油气管道的风险分析(续一)

Risk Analysis of Oil and Gas Pipelines(2)

对引起管道事故的腐蚀、设计和操作三方面因素进行了分析评分。腐蚀破坏是管道中最常见的破坏,腐蚀主要指内腐蚀和外腐蚀,内腐蚀风险的大小与介质腐蚀性强弱及防腐措施有关,其风险分数占腐蚀总分数的30％,外腐蚀是管道腐蚀的主要因素,与阴极保护、外涂层质量、土壤腐蚀性、使用年限、有无金属埋设物、电流干扰及应力腐蚀等因素有关,分别对这些因素进行分析评分;原始设计与风险状况有密切的关系,设计时为简化计算所选用的设计系数与实际情况有差异,这直接影响了风险状况,设计因素主要包括钢管的安全因素、系统安全因素、疲劳因素、水击可能性、水压试验状况、土壤移动状况几个方面,并对其进行评分;风险的一个重要方面来自人的误操作,据美国统计,人的误操作所造成的灾害占灾害总数的62％,管道的误操作主要指设计、施工、运营、雏护四个方面的误操作,要减少误操作,首先要提高人的群体素质,其次要加强第三方监督。

The three factors contributing to pipeline failures (corrosion, design and operation) are analysed and scored. As the most common destroyer of pipeline , corrosion mainly refers to internal and external corrosion. The internal corrosion has a risk score accounting for 30% of the total score for corrosion risks, depending upon the corrosiveness of the medium transported and the measures taken for corrosion control. The external corrosion, being a key factor in pipeline corrosion, relates to the following factors which are analysed and scored respectively: cathodic protection, coating quality, soil corrosion property, service age, buried metallic structure (if any), current interference, stress corrosion, etc. Original design has a strong bearing on risk. The design factor taken for the purpose of simphfing calculation will influence directly the risk condition due to its deviation. The following design factors are scored: the safety of steel pipe, the safety of system, fatigue, surge propability, hydraulic testing, and soil displacement. One important source of risk is incorrect operation. According to American statistics, about 62% of the failures result from incorrect operation, which usally occurs during design, construction, operation and maintenance. Improving the overall staff quality and enhancing third party supervision can minimize incorrect operation.