Think about it techs even do repairs to the o-ring seat on a tank if needed PSI/PCI sells the tool to resurface the seat. As stated valves are another story as they are commonly rebuilt / repaired and the parts and tools to do so are available. In fact PCI/PSI gives a valve repair technicians course. I took it at DEMA last year as part of their certification suite which includes Oxygen cleaning, Edi Current and Visual Inspection Tech.