stainless steel water tank repair

[rescuesailor]

I have a large stainless steel water tank located in the bilge of my boat. While removing a steel fuel tank I nicked it with my recipricating saw. The result is a small leak in the corner. I have some welding experience but I am not sure the best method of repair. The tank cannot be removed and getting a TIG welder inside is going to be next to impossible. Machines too big, cables too short. Any ideas?

[Rachel]

I'm about as far from a welding expert as you can get, but I do know that a Miller Dynasty welder was used for repairing welds inside a stainless diesel tank. I think the machine itself was left on the dock and only the weldor and part of the welder were inside the tank. Maybe this would still be too big, but I thought I would mention it.

This is the Dynasty 200; I'm not sure exactly which model of Dynasty was used, but it did look about like this one:




Rachel

[bcooke]

A gooey two part sealant would probably work as a bandaid. They make stuff that seals automotive fuel tanks and is sold at NAPA. Not sure about the health implications but there won't be much contact with the water so I imagine it would be okay. I know that stuff (can't remember name) gets rave reviews and seems to work extremely well.

Welding is the real fix but since we are talking about water, and not something bad like fuel, I think you could try the cheap and dirty sealant trick and see if that works.

[okawbow]

I have a large stainless steel water tank located in the bilge of my boat. While removing a steel fuel tank I nicked it with my recipricating saw. The result is a small leak in the corner. I have some welding experience but I am not sure the best method of repair. The tank cannot be removed and getting a TIG welder inside is going to be next to impossible. Machines too big, cables too short. Any ideas?

I used to work in industrial maintenance, and often made repairs to thin stainless with silver solder. The surface needs to be perfectly clean, and the temperature just right. A small gas/oxy torch or sometimes even a propane torch will do the job. You need to use a good flux an should use a cadmium free silver solder for a drinking water tank. Get the metal a dull cherry red before applying the solder. There is also a plumbing solder known as silver-bearing solder that is 5% silver and 95% tin. It flows at 450 degrees F. if the tank is thin enough, you might get that solder to flow with a propane torch or a heavy duty soldering iron. It is drinking water safe, also. It requires a flux.

[Peter]

Would JB Weld work, or is the area needing repair subject to a lot of flexing?