I have a 80 gallon hydraulic tank on a drilling rig that feeds 4 pumps Im upsizing one circuit from 18 gpm to 29. the hydraulic tank is precharged with 10 psi of air to help feed the pumps. I have a 3/4" port for the feed line to the pump it had a 3/4" hose for the intake. Im thinking I need to upsize the port in the tank. its .250 wall on the tank. the question is how can I weld a bung on it while it has about 20 gallons in it. i was thinking about welding the bung and then drilling with a hole saw through the middle of it. just trying to figure out how to make sure it doesnt go boom. pulling the tank out and draining it is a 40 hour job needing a crane. so I need ideas if its possible to do it in place I dont have access to the inside to put in a bulkhead fitting. thanks for any advice.