Mechanical Behavior Analysis And Residual Life Evaluation Of Hydrogen-induced Bubble Defect Pressure Pipeline

Hydrogen-induced bubble flaw is a more common pipeline defect in the gas pipeline.Once the gas pipeline is exposed to hydrogen bubbling defects and is not treated in time,it is easy to cause pipe failure,which can cause economic loss and casualties.In this paper,the fracture parameters of hydrogen-induced bubbling cracks in different working conditions are calculated to determine the crack propagation trend,simulate the propagation state of bubbling crack,explore the general rule of hydrogen bubbling expansion in the pipeline,and finally calculate the defect pipeline of the remaining strength,to ensure the safe operation of gas pipeline.The research of the subject has important engineering significance and certain theoretical value.First of all,the finite element model of hydrogen bubbling pipeline is established by ABAQUS finite element software.The fracture parameters under different working conditions are calculated according to the established finite element model and the regularity is obtained: with the increase of the ellipticity(b/a),internal pressure(P),hydrogen pressure(Pq)and crack length(a)of the bubbling crack,the corresponding fracture parameter increases and the probability of crack propagation increases;With the increase of the bubble crack depth(h),the corresponding fracture parameter decreases,indicating that the more the bubble near the inner wall of the pipeline more expansion of the risk.Then,the correctness of the finite element model is verified by the simulation of the bubble expansion of the bamboo channel.Through the expansion simulation of the bubble crack under different working conditions,it is found that under the condition of the diameter of the pipe,the internal pressure and the initial diameter of the crack,the greater the hydrogen pressure,the greater the height and diameter of the bubble.And the relationship between bubbling height and bubbling diameter and hydrogen pressure is quadratic parabolic function.Simulation of two bubbling pipes: through the expansion of two bubbling cracks with different distances in the same pipe,when the distance between the two bubbles is less than 5 mm,the interaction of the two bubbling must be considered,when the distance between the two bubbles is greater than 60 mm,the interaction between the two bubbles is relatively weak,we can only select one of the bubbles for simulation.After that,the relationship between the hydrogen pressure and the total concentration at t =20?,30 ?,100 ?,200 ? is calculated,and the hydrogen pressure-bubbling height at DN= 200,350,650,800 mm is obtained.Hydrogen pressure-bubble diameter relationship diagram.According to the concentration of the pipeline to calculate the total concentration of hydrogen in the bubble can be obtained at the bubble at the hydrogen pressure value,which can be based on the trend to find the hydrogen pressure under the bubble height and bubble diameter value to calculate the case of the remaining strength.Finally,the residual strength of the hydrogen bubbling pipeline under different hydrogenpressure is calculated and evaluated by using the finite element method,and the residual strength of the defective pipeline under different hydrogen pressure is obtained.