Research On Pipeline Reliability Based On Gas-liquid Two-phase Flow Corrosion

Natural gas gathering and transportation pipeline is widely utilized in oil and gas exploration and transportation,to ensure its safe and reliable operation is of vital importance.Gas-liquid flow usually exists in gas gathering and transportation pipeline and the internal corrosion is one of the most common attributing factors to failures of pipeline.Based on this,this paper incorporates the corrosion growth model of gas-liquid flow and the structural reliability evaluation model to calculate the failure probability of corroding pipeline under gas-liquid flow.Firstly,the internal corrosion rate of gas-liquid flow pipeline under different flow patterns is calculated according to the flow characteristics of gas-liquid flow with the phase equilibrium model,the gas-liquid flow model and the corrosion rate prediction model.According to the limit state functions recommended in the ASME-B31 G specification,considering the uncertainty of pipeline operation and manufacturing,the failure probabilities of the small leak and burst failure is obtained based on Monte Carlo approach and the calculation result of the internal corrosion growth rate.Finally,the calculation method for internal corrosion failure probability is proposed to obtain the failure probability of a gas-liquid flow pipeline.When there is no effective internal inspection data or the actual pipeline transmission process changes,this method can effectively predict the failure probability and ensure the safety of oil and gas pipeline transportation.Finally,aiming at the lack of correlation research on reliability assessment methods of corroded pipelines,a corroded pipeline reliability evaluation method that comprehensively considers the correlation between parameters and defects is proposed.The results show that the correlation parameters of failure probability is greater than the influence of the correlation between defect effect on the failure probability.The correlation between the maximum defect depth and defect length,defect depth growth rate and defect length are the greatest impact on the failure probability.In order to accurately predict the probability of failure of the corroded pipeline,the data of the maximum defect depth,defect length,and defect depth growth rate should be collected.