Welding space vacuum technology

The objective was to assist the EH 42 Division in putting together a vacuum system that could attain the desired pressure and be large enough to accommodate the gas-metal arc (GMA) welding fixture apparatus. A major accomplishment was the design and fabrication of the controller/annunciator for the 4' by 8' system. It contains many safety features such as thermocouple set point relays that will only allow inlet and exit gas and vacuum valves to be operated at pre-selected system pressures, and a fail safe mode for power interruptions and operator mistakes. It is felt that significant progress was made in this research effort to weld in a vacuum environment. With continued efforts to increase the pump speeds for vacuum chambers and further studies on weld fixtures and gas inlet pressures, the NASA program will be successful.