Mitigating Potential Hazards of TIG Welding on Spacecraft

Electric arc welding is commonly employed to join metal tubing pieces that are part of a spacecraft's propulsion subsystem, and is usually done early in the spacecraft assembly before potentially susceptible electronics are integrated. On occasion, however, a propulsion component may require repair or replacement, necessitating cutting of propulsion lines and welding in new components. If repairs are required after the electronics and harnessing are integrated, then the interface circuits of those electronics will be exposed to electrical transients induced in the harness wires by the electric and magnetic fields radiated by the propulsion lines being welded. This paper reviews the nature of the electrical transients caused by arc welding of the propulsion lines and the magnitude and duration of the induced transients coupled onto nearby harness wires (shielded and unshielded) and delivered to interface circuits of different load impedances. Mitigation techniques are addressed for circuit types that would be potentially damaged.