LOW-CYCLE CORROSION FATIGUE AND RESIDUAL LIFE PREDICTION OF PIPELINES

Aiming at the severe corrosion fatigue tendency of the pipeline in-service,a new low-cycle corrosion fatigue method of using a large purely-bended sample(480 mm×38 mm×12 mm) was developed.The samples were cut from the buried arc welded spiral pipeline (X70) used for West-east gas transmission.An experiential formula about crack growth rate,dl强激光与粒子束dN=a+b·ln(p·ΔK),has been established via the experimental results in two different environments of atmosphere and 3% NaCl solution,and the two constants of a and b were identified.The residual life of the sample was estimated by Maple software under two different conditions.The obtained 3D relationship charts have the directive meaning in solving the actual oil and gas pipeline problems.