Research On The Remaining Strength And Remaining Life Of The Pipe Body Of The P5 Gas Field Production System

"Pipe" in this study,is the tublation of the channel transporting the natural gas from the well to the gathering system,which is the main object of the investment.The pipe of the production system in P5 Gas Field was exposed to relatively serious corrosion,for instance,not only the pipeline has beed perforated,but the perforations and corrosion pits were found in the tube.Because the corrosion of the pipe is inecitable,the corroded tublations must be replaced as the preduction years are increasing and their strength is decreasing.However,a blindly replacement of a tublation is a waste of money,which improve the cost of the gas production.Therefore,the corroded tublations should be evaluated in considering of the accepetable risk,to utilize the maxium value of them.The study of the corrosion regular of the pipe in P5 Gas Field is the foundation of the assessment.The maintence records,materials,water constituents and gas constituents are researched to confirm the corrosion type of the pipe in P5 gas field.Based on this research,some tublations that are badly corroded are choosed to be detected with wall thickness measure and metallographic phase test.With the result of the detection,the regular and the influences of the corrosion are further analyzed.According to the corrosion type and failure mechanism of the pipe in P5 Gas Field,volumetric type flaw models are adopted to the residual strength assessment of the pipe in this paper.As it is different between the loading,failure mechanism and materials of different kinds of pipes,ASME B31G method,which is closely combined with engineering production and based on burst test,is employed to the assessment of corroded pipelines,while the fracture mechanics to the tube.The life prediction of the corroded tublations is modeled,in the basis of the assessment method of corroded pipe,by quantifying the influences of reliability containing the detection error,corrosion rate and material strength,restricted with the size boudary,strength boundary and reliability boundary.Then,the numerical solution method for multiple integral and the Monte Carlo method are applied to solve this model.The residual strength of the corrode tublation is evaluated by the residual strength assessment method.Based on the assessment result,combined with the research of the influence of the reliability,the life of the corrode tublation is predicted by Monte Carlo method.The life prediction result of pipeline corresponded to different measured size of flaw is computed,and the life of the tube that is badly corrode is predicted.In all,a certain researching achievement is gained in this papper,which has been applied to engineering.