Specific features of applying machine welding with drop transfer in repair of operating pipelines

Introduction. Repair of pipelines under pressure of pumped media by means of welding is relevant to reduce the complexity of work. However, it may reduce the safety of work. To solve this issue, the authors consider applying the technological processes of machine welding with controlled drop transfer.Aim. To determine the main parameters of technological processes of machine welding with controlled drop transfer, affecting the safety of welding.Materials and methods. The authors developed a theoretical model for calculating the working thickness of a pipeline wall under pressure which they used for calculating the strength during welding. The dependence of the pipeline wall thickness at the edge of the penetrated hole on the internal pressure was also used in the calculations.Results. It was found that machine welding with controlled transfer of metal drops allows the wall penetration depth to be regulated by changing the welding variables. This significantly increases the safety of welding on pipelines under pressure of pumped media, compared to other types of welding. The developed welding processes ensure the safety of welding operations by means of a smooth and accurate control of the wall penetration depth. This is achieved by the correct selection of the background and peak current, control of the drop transfer process by arc voltage, control of the amount of weld metal and the heating temperature of welded structures.Conclusion. Recently, a number of repair technologies have been developed to improve the quality of welds in the construction and repair of trunk pipelines. The highly significant results of research on the development of machine welding technology with controlled drop transfer allow this technology to be recommended as an effective way to improve the safety of welding operations on pipelines under pressure of pumped media.