I have a customer with a process chiller that has a refrigerant leak in the evaporator shell & tube heat exchanger. It is a brass shell and the leak is from a crack around the end bell where the liquid line is soldered in. The manufacturer is no longer around, so I would like to repair it if possible. Has anyone done a repair like this and what did you use? I don't think silver solder would fill in the crack good enough to hold up. Does anyone have a good idea what I can use to fill a crack in the brass shell?