Leaking at welded fitting on tank? can i jb weld around the fitting

Many have tried same, and only a few have been successful, and at best, only temporarily. Believe it or not, I had 3 do the exact same thing last year, corroded right through the meaty part of the fitting, where you would think would be the last place it would eat through. Being in the RV Service trade, I only want to have to fix it once, and don't want to be responsible for any future floods when away from unit so I replace the tank. I've seen some wild fixes over the years, such as a piece of thick rubber hose over the pinhole with a gear clamp (hose clamp) tightened over it to stop the leak, and it was actually working to stop the leak. Your choice, your gamble, but if you decide to try a quick fix, I'd make real sure I shut the pump or city water supply off when your not going to be close by or in the trailer for any amount of time just in case. Hate to come back from a walk and see water running out the door of the trailer. Good Luck.