Peculiarities of manufacture of large diameter welding pipes and method of their heat treatment

Purpose. The aim of the work is to assess the possibilities of manufacturing large diameter pipes for main pipelines, analysis of requirements for pipe billet in terms of chemical composition and mechanical properties, as well as prospects for heat treatment to improve mechanical and operational properties of main pipelines. An overview of the requirements for sheet metal for the manufacture of large diameter pipes, as well as the features of heat treatment to remove the final stresses. Peculiarities of weld heat treatment and influence of temperature on mechanical properties and structure of both base metal and welding zone are considered. The methods. The methodological basis of the study included analysis, comparison and systematization. To achieve the goal of research and solving the tasks used a set of modern research methods and developments of world manufacturers. For large diameter pipes it is better to use the periodic method of induction heat treatment, which will provide flexibility in the implementation of heat treatment modes. Findings. Systematized requirements for the quality and chemical composition of materials for pipe blanks. As a result, it was found that we can recommend a change in chemical composition, control Матеріалознавство та галузеве машинобудування 165 of thermomechanical rolling parameters and accelerated cooling technology, which can result in a bainitic structure that will improve the mechanical and operational characteristics of main pipelines. When testing the technology of heating welded joints, it is necessary to carry out temperature control in all the most responsible areas of the welded joint. The originality. The scientific novelty is the development of recommendations and systematization of existing methods and technologies for the manufacture of pipes for main pipelines. Practical implimintation. The main requirements to the main pipelines are considered in the work. Systematized requirements for rolling for the manufacture of pipes, features of heat treatment and its impact on the structure and mechanical properties of the base metal and weld. The main methods of heat treatment and their influence on the properties of large diameter pipes are shown.