Western Sichuan Gas Pipeline Failure Analysis Technique

This paper has studied the failure laws of the nature gas pipeline, which covers the west area of Sichuan Province. Related to the lots correlative literatures, the field test about the pipeline's failure data has been done. With the latest studies about the nature gas pipeline's failure law and the technology of reliability evaluation, the new ideas of the failure analysis and forecasting for nature gas pipeline have been brought forward. In order to improve the management level, these achievements already put in the field nature gas pipeline's management program.Starting with the failure factors of Xin-Qing pipeline and Huan-Jin pipeline belongs to South-West Petroleum Bureau, by using CIPS and DCVG , the major factors affecting the pipeline's corrosion degree have been found. Combining the testing data of CIPS and DCVG , the corrosion degree of these pipelines was calculated. The reason and forming mechanism of the IR and the experiment study are also discussed in the paper. According to the basis theory of the failure analysis, combining the test data and the operation conditions of the nature gas pipeline in west area of Sichuan Province, firstly, the major failure factors are analyzed. Secondly, the failure analysis tree of the nature gas pipeline is put forward in west area of Sichuan Province by using the FAT method. Thirdly, based on this failure analysis tree, the major failure factors and relative reasons are discussed. The analysis in quantity involves the statistical failure probability by direct no cross analysis and sample analysis method. The calculating ways used to determine the important degree, probability degree and critical important degree are also confirmed. Related to the failure probability, we can understand the weaknesses in the pipeline operating system, so we give an expansion of the evaluation about the failure effect. In order to solve the difficulties in the gathering field failure data, and combining the experiences of field engineers, the fuzzy theory is successfully applied to solve this question. Using this method, you can describe the failure probability with the fuzzy count, and deal with the uncertainty and random of the failure events at the same time successfully.Based on the corrosion defect description, the statistical analysis and rupture mechanics, the evaluation method used to analyze the failure stress of pipeline under a certain corrosion defect size is confirmed. By using the finite element theory, the non-linear analysis module is put forward to analyze the residual stress of the corrosion pipelines. This module combines the pipeline's size, location and tympanites effects, which can be used as the fine analysis for residual stress. And with the J integral safe evaluation method, the main rapture type of the nature gas pipeline is the tent rapture. With the change of the defect size, failure probability, the residual life is also analyzed in the paper.Combining the achievements in the paper, the software is also developed for failure analysis. The program has the excellences of simple operation, wide usage, high precision and so on. It can be used to improve the safe management level for nature gas pipelines.