GrantJ and Neil, on a few smaller mines sites I have worked on they do sometimes fix tanks (in emergency cases) when they don't have a replacement or time to stand the only front line machines down (exacvator normally) they would remove tank if they had no access to repair area and would run the exhaust off a toyota land cruiser (diesel vehicle) into the tank then wait I think it was 3 hours to fully fill tank with the fumes then start the repairs most of the time it was a cracks to be welded, I did find the copy of the repair site procedure and didn't realize to would be allowed on site but it was done many times. Petrol to diesel tank im guessing it would be a similar process to follow.

I like it when a plan worked out. Good for another 50 years probably! JM

insertion rubber works well, i have also used gasket paper or cork gasket sheet. you will get insertion rubber at most irrigation pump suppliers as its used for gaskets on pipe flanges. many industrial suppliers have it too. available in several thicknesses

when you put it back on put spacers on the bolts and leave an air gap under it, dont put any material under it

i did it on my autopatrol grader and it has seen about 5 hours since. cat 22 is not going to see many hours either

I have used the JB weld Marine grade epoxy on a couple of items here; not my style, but cheap and quick fix to keep something operational until time for proper repair/replacement. Good luck on your fix Grant. JM

purge with nitrogen gas and go to cutting and welding nitrogen gas will keep it safe i weld alot of tanks

Hudco, is nitrogen better than CO2 or is it just basically fill it with an inert gas? My welder mentioned running the exhaust from his truck into the tank. I think that there may be several ways. Grant.