Risk Evaluation And Structure Integrity Assessment For Industrial Pipeline

The industrial pipline, as the artery in human body, which connects the chemical industrial equipment is very important in chemical equipment system. Whether the piping is operated normally influences the safety of the chemical device. The pipeline of hydrocracking apparatus is mostly subjected to the action of hydrogen, high temperature and high pressure. For assuring safe operation, it is extremely important to assess the risk and integrity of the pipeline. Firstly, the risk levels are attained by risk evaluation of all pipes. Secondly, the effective inspection strategy is established based on the risk levels. Lastly, the integrity assessment is carried out for the high risk piping. The main contents and results of this dissertation are as follows: (1) The RBI technology and ORBIT software are used to analyze the 366-pipe system of the hydrocracking apparatus. The results show that there is 1 high risk pipe, 250 middle high risk pipes, 49 middle risk pipes and 66 low-risk pipes, and the thinning area by corrosion is primary failure mode of the pipelines. (2) Pipes with high risk and middle high risk should be attached great importance in investigation strategy of RBI, but these results are often quite different from traditional regular inspection. Risk based inspection can avoid excessive and insufficient inspection, which not only enhances the safety of the pipeline system, but also reduces the cost and increases the profit. These merits indicate that RBI is a scientific and advanced technology of equipment management. Thus, it is worthwhile to try and extend the technology in domestic petrochemical enterprises. (3) A stress distribution of high-risk pipe is analyzed by finite element method (FEM). The results show that, when temperature, pressure and gravity force applied simultaneously, the total stress of pipeline is not high and maximum stress locates at the elbows. The pipeline's strength is enough through stress analysis. Temperature load has significant effects on the stress and displacement, while internal pressure and gravity force of the pipeline have little influence. (4) Using plastic failure assessment method of pressure piping containing LTA defects, tables of the maximum allowable LTA defect are obtained, by which the safety of the pipeline can be made conveniently and quickly according to inspection results of wall thickness.