Originally Posted by Breck09
[...]Well I just looked at it and it isn't a part that can be tightened. I wonder if I could use anything to try and seal it without welding. Would silicon caulking or something like that work?
Under the circumstances, it's definitely worth a try, not much to lose at this point. Never had that happen, but I'd dry the underside of the lid best as possible then apply the silicone sealant to the entire relief valve opening, put the lid back on and put a couple of pounds of pressure on it for 24 hours and hope the sealant plugs the leak.
Then I'd immediately order a new lid...
Cheers - and good luck