Keyword: «electrofusion»

This paper presents the research results on the technologies developed for welding polyethylene pipes, which allow welding at ambient temperatures below the standard ones without temporary heated shelters. Two types of welding were considered: with a heated tool butt (butt) and an embedded heating element (electrofusion). The results of short-term and long-term tests of welded butt and socket joints show the effectiveness of the proposed technologies for the operational welding of polyethylene pipes for gas pipelines at low ambient temperatures.

A fundamental hypothesis has been made in technology development for welding polyethylene pipes at low ambient temperatures. The priority of the thermal process is shown, which is the key for all processes occurring during welding. We propose to introduce additional preheating operations, equalize temperatures in the heat-affected zone (HAZ) to the temperature acceptable for welding, and ensure cooling of the HAZ according to a pattern typical for welding at regulated temperatures. Mathematical modeling methods are used to determine the parameters of heating, temperature equalization, the dimensions of the heat-insulating chamber, or the thickness of the layer of heat-insulating material for specific low ambient air temperatures.