Mash Tun O-Ring Disaster

I'm converting a 10 gal Home Depot round cooler into a mash tun.

Here's the problem. The 3/4" o-ring (on either the inside or outside) slips into the wall of cooler whenever I tighten, thus breaking the seal. It leaks.

What am I doing wrong?

Thank you for the help,
Cistercian

had the exact same issue, and once I got it to stay and added hot water it began to leak again. I finally got it to stay in place with a small leak, 1 drip every 3 seconds, so I used two park epoxy on the outside of the cooler around the washers. Probably not the best idea but it seemed to work for me.

Go to the plumbing section of your tool store and look for silicone sheeting used to cut custom gaskets and make yourself a big, flat washer/gasket.

Could it be that Home Depot 10 Gallon jugs have different size openings at the bottom?

I just don't get it.

Cistercian

That's what it sounds like to me. For the o-ring to work properly, the hole must be almost exactly the size as the nipple that goes through. As was previously mentioned, silicone washers will give you more bite, if the hole is too big. Good luck.

The best way to get a good seal is to cut a clearance hole through the outter wall big enough for the body of the valve and a hole through the inner wall the size of the thread. Clear the insulation out so that the body of your valve will hit the inner wall. This way you are only compressing on a thin piece of plastic, not trying to squeeze two walls with insulation between them together.

Here's one with a plastic ball valve:

AnOldUR said:

The best way to get a good seal is to cut a clearance hole through the outter wall big enough for the body of the valve and a hole through the inner wall the size of the thread. Clear the insulation out so that the body of your valve will hit the inner wall. This way you are only compressing on a thin piece of plastic, not trying to squeeze two walls with insulation between them together.

Here's one with a plastic ball valve:

Click to expand...

That's a good idea. I did a variation of this (or, took a different approach to fix the same potential problem): I dug out the insulation around the hole and filled it with Bondo. You can tighten all day and that part of my cooler isn't going to budge.

Seems like figuring out why it's slipping is key for you. Is the hole too big or do the cooler walls cave when you tighten? (Or something else?) Both problems can be fixed pretty easily, but require different solutions.