MONITORING OF THE TOUGHNESS OF THE MATERIAL OF THE MAIN GAS PIPELINE AFTER LONG TERM OPERATION IN ARCTIC CONDITIONS

The problems of ensuring the reliability and safe operation of long-running hazardous industrial facilities, in particular gas pipelines, after 50 years of operation are considered. The goal of the work is developing a method for assessing metal embrittlement of long-running main gas pipelines (MG) using a non-destructive method for monitoring and improving operational reliability. Experimental studies of the samples of the pipes of the main gas pipelines revealed the parameters most sensitive to the processes of structural degradation. The applicability of those parameters to assessing the degree of degradation is substantiated. Analysis of the results of mechanical and acoustic studies revealed correlation with an essentially large value of the correlation coefficient. Based on this correlation, a method for assessing the toughness has been developed. The experimentally obtained limit values of the studied characteristics at which the operation of the structure becomes dangerous are presented. A flowchart has been developed for monitoring changes in the toughness of the gas pipeline steel after long-term operation. The experimental results and developed method for estimating the limiting state of the gas pipeline material were used during technical diagnostics of non-project sections of the Mastach — Berge — Yakutsk gas pipeline to determine real operational characteristics and form a database of the studied indicators for their further monitoring. The proposed method will improve the efficiency of accumulated information on the structural reliability and provide the possibility of assessing the degree of pipe metal degradation without conducting mechanical tests and making samples in the process of technical diagnostics thus reducing the material costs for conducting scheduled maintenance of the pipelines.