The analysis on reliability and affecting factors of X80 pipeline girth weld
A multiple-limit state function of the girth weld containing a crack defect was established for the defect characters of girth weld,and together with distribution characteristics,the reliability analysis method of X80 pipeline girth weld based on Monte Carlo was formed.Meanwhile,the sensitivity analysis of the girth weld was made,and the sensitivity of each parameter was obtained.The results show that for an X80 pipeline with a wall thickness of 18.4 mm and an outer diameter of 1 219 mm,welded using a self-shielded flux-cored arc welding process,the failure probabilities of the analyzed girth weld under stress-based failure criterion 1,stress-based failure criterion 2,and strain-based failure criterion were 8.2×10-7,5.9×10-7,and 3.5×10-7,respectively.All three of them fall within an acceptable safety level without the need of maintenance or replacement.External load,crack depth,fracture toughness and yield strength have strong influence on failure probability of girth welds.Thus,the reliability of girth welds can be enhanced by controlling the external load,reducing pipeline defect size,or increasing yield strength and fracture toughness so as to ensure safe operation of pipeline.
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