Safety Assessment on Pipe-wall Sag of Oil Pipeline

A number of sags on pipe - wall of a oil pipeline produced due to the road adjacent the pipeline construction. On the basis of this kind of defect, MSC/NASTRAN and MPC/PRIFIS softwares have been adopted to analyze the safety of the pipeline. The analytical results have shown that there is still a high safety allowance in the sag zone under the design pressure. However, the defect size for allowable critical crack is small due to the stress concentration on sag zone. Therefore, the protective measure should be taken to prevent the sag zone from cracking.