Influence of temperature and time modes of polymer pipes welding at low temperatures on the structure and properties of materials of compounds. Part I. Calculation of the heat process

Abstract

Subject of research: thermal process of welding PE100 saddle branches to polyethylene pipes of existing gas pipelines at low temperatures. Purpose of research: development of an effective method for welding saddle branches to polyethylene pipes of gas pipelines at ambient temperatures up to minus 50 C based on thermal process control by introducing preheating into the technological process with subsequent cooling to equalize the temperature and cool the joint under a layer of thermal insulation material of calculated thickness. Methods and objects of research: in the first part of the work, the object of study is the non-stationary thermal process of welding. The mathematical model of the thermal process takes into account the heat of the phase transformation of polyethylene in the temperature range, the dependence of thermophysical characteristics on temperature and the degree of crystallinity of the material. Main results of research: calculations have determined the welding parameters of the saddle branch, which ensure the flow of the thermal process according to the regularity inherent in welding under conditions of permissible ambient temperature. It is expected that the control of the thermal process will make it possible to obtain a structure of the welded joint material that ensures the strength of the seam corresponding to the strength of the seam obtained by welding under conditions of acceptable temperatures.