I have a vertical air compressor in daily use in my business which has had a thread failure at the at the top of the tank where the tank's intake check valve installs.  Both the 1/2"-14 female threads in the tank bung AND the male threads on the check vale are stripped.

I have a new check valve on order, but I need some sort of repair fitting for the tank bung that does not require welding.  Does anyone make an oversize "bung repair" fitting for that thread size?  Perhaps something with a male 9/16"- 5/8" OD thread size and a a 1/2"-14 ID thread?  I can cut threads in the tank (and I believe that I have the needed reinforced area to do so), but I cant weld and I don't want to move the tank out of the tiny wooden building that it is in to have it welded.
Any other suggestions . . ?

Jeff