Special aspects of the process of welding fixed joints between thin-walled heat pipes made of aluminum alloys for the ISS modules

Abstract

The process of joining thin-walled small-diameter pipes made of aluminum alloys using welding has some special aspects to it. Volumetric analysis shows occurrence of welding defects in the form of cracks, pores and oxide inclusions that are inadmissible according to the requirements of technical standards. This paper discusses a process for welding heat pipes to be used in rocket and space hardware, as well as presents solutions for scientific and technological problems encountered in the course of their making, such as: • Methods of preparing parts for welding and the process of welding composite members of heat pipe structure made of aluminum alloys with the use of special tooling; • An illustrative example of using effective creative assembly of pipes for welding with the use of a coolant which provides additional removal of heat from the area of the welded joint; • A well-chosen automated mode of welding fixed joints between thin-walled pipes using modern main and auxiliary welding materials and an inert protective gas that has a high degree of purification owing to a reduction of its contaminants content and its storage in bottles of an advanced design; • Use of a welding wire made to special specifications and stored in specialized vacuumed bags made of polyethylene film; • An analysis of possible methods of welding heat pipes and development of the best process for their welding that takes into account the physical, chemical and mechanical properties of the material and special operational aspects of structure. Key words: sealing of heat pipes, fixed joints between pipes, aluminum alloys, thin-walled small-diameter pipes