Study On Reliability Evaluation Method Of Oil Pipeline System

The concept of reliability of oil pipeline systems includes two aspects: system security and system transportation capacity.However,researches on the reliability assessment of oil pipelines are mainly focused on the pipeline structure integrity and reliability of units.However,the importance of transmission capacity in reliability assessment has not been emphasized.In this paper,indicators are developed for reliability assessment of oil pipelines from two aspects.Then a method is proposed to estimate the reliability based on reliability theory and system engineering methods.The method includes three parts: the risk assessment of oil pipeline leakage,the safety evaluation of waxy crude oil pipeline shutdown and restart,and the evaluation of the transportation capacity of oil pipelines.Firstly,the index system of reliability evaluation of oil pipeline system was established.The index system can be divided into two categories: safety index and availability index.Compared with the criterion to determine the target level of safety of the international standard ISO16708 and CSA Z662-2007,this paper proposed leakage risk index to measure the risk of pipeline leakage.The safety evaluation index of oil pipeline system was composed of leakage risk index,the maximum allowable shutdown time and the lowest safety inlet temperature.The concept of availability in reliability engineering was introduced,which was used to characterize the transportation capacity of oil pipeline system.Secondly,a method for evaluating the safety of oil pipeline system was presented.The traditional two-state leakage evaluation method can’t reflect the equipment degradation state,so this paper put forward the method of multi-state safety evaluation of oil pipeline system.Congelation as one of the security problems of the pipeline system,the existing research had proposed a method to determine the maximum allowable shutdown time and the lowest safety inlet temperature of waxy crude oil pipeline based on reliability.This paper analyzed the main factors causing congelation and the logical relationship between the various events through the Petri net of oil pipeline congelation.Finally,a method for evaluating the availability of oil pipeline system based on Bayesian network was presented.In order to evaluate the transportation capacity of pipeline system,this paper introduced the concept of availability in reliability engineering.Then introduced the application of Markov model to evaluate the pipeline system availability,and analyzed the limitations of the Markov model.Therefor a method based on Bayesian network was proposed to evaluate the availability of oil pipeline system.This method can be used to calculate the availability of the system based on the prior probability and the probability of each node in the topology of oil pipeline system.In summary,the reliability evaluation index was established according to two aspects of oil pipeline system reliability,and the evaluation method was furtherly discussed,providing a reference for further research.