Research On Reliability Of Oil And Gas Pipeline In Confined Space And Explosion Risk Assessment

Nowadays, with the high speed of construction and development, beneath the city there are large kinds of pipelines which interlaced together and become a complicated pipe network. Due to the lack of comprehensive planning, pipelines may lay across the confined space or near the underground confined space like cable trench or drainage channel. Once the pipelines break down and explosive medium like petroleum or natural gas diffused into the confined space, the situation will become very dangerous. The explosion accidents happen in Shandong Province and Taiwan Province have let people alert the severity of this kind of situation. There are enough urgency and realistic significance to analyze this kind of situation. Therefore, this thesis is trying to study the reliability of the pipelines which related to the confined space and the severity of the confined space explosion. The main contents included in this thesis are as follow:(1) Underground pipelines Mechanical model construction and structural reliability analysis. Two mechanical models were constructed to analyze two typical types a pipelines relative to the confined space: lay straight across or lay nearby the confined space. And the limit state functions are established. Using the Monte-Carlo method, A pipeline’s reliability was analyzed and the sensitivity to relative parameters were analyzed.(2) Confined space explosion numerical calculation and blast wave propagation pattern analysis. The finite element model about confined space with explosive gas was established using fluid-structure interaction technology. With the FEM model, the blast wave propagation pattern was analyzed by overpressure data collected from the numerical calculation result. The damage level that caused by the blast wave to the human being and the building was established. And according to the FEM result, a fitted curve was given for assessing the damage that a confined space explosion can caused. This provides the calculation basis to the risk assessment.(3) Confined space pipeline break and explosion accident risk assessment model set up. Using the risk matrix method, the accident happen probability and the consequence severity were considered by pipeline reliability and blast wave damage level calculation. The criterion for the risk assessment was set up by considering both personal acceptable death probability and social acceptable death probability. In addition, the economic loss was also set as a criterion for the company to assess the risk level. A complete and systematic accident risk assessment model was set up.(4) Confined space pipeline break and explosion risk assessment model engineering application. Using the risk assessment model that has been set up, a pipeline located in Guangzhou city is analyzed. From the specimen that collected from the pipeline, a series of experiment were carried out to detect the pipeline corrosion type and the mechanical property of the pipeline. The reliability of the pipeline and the consequent of the explosion was calculated. The risk assessment result reveals that the risk of the pipeline now was located in the acceptable area. But considering the corrosion and the deterioration of pipeline material, the risk will rise in the future. The risk prevention and control scheme was discussed.