I was having problems with mine leaking too. I chased the threads and used new bolts to make sure I was maximizing torque to clamping load ratio, and I made my own gaskets out of .080 thick annealed copper VCR gaskets for I believe a 2" gland. they start out flat and conform to a cone shape when you torque the bolts down. I hold them in place with a couple small dabs of copper RTV, which does eventually burn off. No more leaks.
I don't have a part number. We stock them for pressure testing at work, and once they're used, they're garbage, so I grabbed a couple out of the scrap bin. I think you can get them at Kurt Lesker online.
You may have to actually call them because I think they only have a partial list online. Most companies will only list up to 1 inch, since systems running bigger than that are pretty rare. Just ask for a 2" VCR copper gasket. Should be less than 10 bucks a piece.
