Effect of Residual Stress on the Destruction of Field Joints of Gas Pipelines Operating in Conditions of the North

Abstract

Welding residual stresses are determined by algebraic summation of stresses by the effect of external loading and can have a significant impact on the performance of welded joints. The present article examines the effect of residual welding stress on the destruction of circumferential butt welds of the gas pipeline sections. The features of the distribution of the welding residual stresses of annular welded pipe joints are considered. It has been established that thin-walled tubes are formed in the inner layers of the sealing elements with growing tension pins forming inside. Analysis of destruction of ring welded joints of the underground and underwater sections of the pipeline was carried out. The welding residual stresses were investigated with X-ray diffraction technique. It is shown that the initiation and growth of macrocracks in the field joints of thin-walled main gas pipelines occur in the heat-affected zone from the interior face of the pipe wall in the zone of high tensile residual welding stress. Analysis of the destruction of real welded joints of gas pipelines has proved that the residual welding stress is the main factor that influences the development of brittle and fatigue cracks in them.