Ultra-High Vacuum Gate Valve Repair
Brief
A research group discovered a leak on a weld seam on the flange of their gate valve. The system was struggling to get down to a operational vacuum pressure for their system. They asked if it would be possible to repair the flange as the cost of a new gate valve was £3,000.
I managed to isolate the section of weld that was leaking but everntually after leak testing I decided to reweld the entire weld seam to solve the leak which took multiple passes. I also used parts of a copper flange to control the amount of heat to prevent the sealing face of teh gate valve from warping.
I concluded that the mode of failure of the flange was that because it had a heavy ion pump suspended from the failed flange below the machine and over the life of the machine it had been cycled in and out of vacuum many timse. This had inefffect caused a micro crack through the stress cycling of going in and out of vacuum over many years.