Reliability Design Method Of Thermal Stability Of Subsea Pipeline With High Temperature

Thermal buckling of pipeline is induced easily under high temperature and high pressure condition,which further aggravates the instability of submarine pipeline,and it is easy to bring about a series of problems such as pipeline rupture and oil and gas leakage.Therefore,it is necessary to study the reliability design of subsea pipeline to ensure the thermal stability of pipeline stay at high le vel.The main research works as follows:(1)The influence of the randomness of the initial imperfection and the soil resistance on the buckling of the subsea pipeline is taken into account for upheaval buckling.Assuming the imperfection and soil friction obey the truncated Gaussian distribution,and the formula for calculating the probability of vertical buckling is deduced.The probabilities of buckling with different effective axial forces are analyzed.Once the probability of buckling is determined,the ranges of imperfection and soil resistance can be obtained.(2)Considering that the randomness of the imperfection and the seabed lateral friction obey the lognormal distribution for subsea pipeline lateral buckling,the formula for calculating the probability of lateral buckling of pipeline with mode one imperfection is presented.A method is proposed to calculate the joint probability of buckling based on the Monte Carlo simulation.The range of imperfection and lateral friction can be obtained when the probability of buckling is determined.(3)It has shown that the larger offset angle and the smaller lateral friction coefficient,the higher probability of buckling at the desired position through the study of the theory of snake-lay technique.Assuming that the randomness of the offset angle at the bend of the laying pipe obey the truncated Gaussian distribution for the snake-lay technique,the formula for calculating the probability of buckling at the bend is presented.This method can be used to evaluate the probability of snake-lay technique during the design phase so that the decision makers are more confident in adopting this technique to prevent the buckling.