International Space Station External Active Thermal Control System lines manufacturing
- Paper number
IAC-06-B4.2.09
- Author
Mr. Stefano Ferretti, Thales Alenia Space, Italy
- Coauthor
Mr. Giuseppe Valenzano, Thales Alenia Space, Italy
- Coauthor
Mr. Walter Cugno, Thales Alenia Space, Italy
- Year
2006
- Abstract
The International Space Station (ISS) has dedicated subsystems to support the life of the astronauts and allow them to perform scientific experiments in microgravity. The control of the temperature and humidity is provided by the External Active Thermal Control Systems which requires a very high level of reliability, because it allows the wasting of the heat loads generated by the equipments and by the crew. The EATCS is then of primary importance for the ISS, and it consists of Heat Exchangers, hoses, Quick Disconnects, radiators, and other elements which allow the ammonia to flow from the Node 2, Node3 and US Lab to the truss structure. Loss of ammonia would mean impossibility of cooling the electronics, avoiding the generation of electrical power and the regeneration of the air (humidity removal, CO2 removal and cooling). Therefore the leakages have to be prevented at the maximum extent. For these reason the assemblies hoses-Quick Disconnects have been manufactured using the Orbital Welding technology, a special TIG process designed for tube welding. The high level of cleanliness required a dedicated development and qualification campaign, which resulted in the definition of a certified welding process that ensure 200 cleanliness class inside the lines. Another challenge is represented by the fact that dissimilar materials have to be joined. In fact the hoses are manufactured in stainless steel AISI 316 L, while the Quick Disconnects are produced in Inconel 718. The planning of the process development in focused steps, as Training, Development, Optimization, Qualification, Repair Qualification, Pre-Production, allowed to reach the goal of having a reliable process in a short timeframe. The study included a research on the influence of some parameters over the others, as Ampere, Voltage, Velocity, Gas Flow and Pressure. The international standards required by NASA, ESA and ISS programs have been included in all the specifications and procedures, covering aspects like metallic materials, welding processes, cleanliness, mechanical properties, susceptibility to stress corrosion cracking, proof and leakage verifications. The process was then also qualified for repair, conducting specific studies on the allowable defects in the welds, and identifying three main critical scenarios. The paper addresses in its conclusion also some issues related to future utilization of this technology in Space for the assembly and repair of fluidic lines of Space stations and planetary settlements.
- Abstract document
- Manuscript document
IAC-06-B4.2.09.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.