The pipe material and improvement state analysis of technological processes for laying main gas pipelines

Abstract

The change in the structural state of the gas pipes’ weld material at different seam cross-sections have been considered. The classification of external and internal defects of the joint material caused by the influence of different types of factors, most significant of which are the material defects in the transition zone of the joint to the pipe base metal. The analysis of atmospheric effects on the pipeline welds materials initiating adsorption and electrochemical processes in the metal microstructure that cause corrosion on the seam outer surface is given. Taking into account the non-stationary mode of pipes loading due to fluctuations in internal gas pressure, corrosion-fatigue damage is also added to these material defects, which cause the fatigue cracks development in the material, leading to a violation of the system tightness and even to welds destruction. The structure of a mobile device is proposed for performing a complex of technological operations for assembling large-diameter ground gas pipeline and for ensuring installation accuracy and maintenance processing of the welded pipes’ edges, automatic welding along the seam perimeter, cleaning, grinding and hardening of the seam material outer surface, applying a protective coating against atmospheric influences. The device facilitates the work of installation staff, increases the reliability and bearing capacity of the gas transmission system installed in difficult terrain.