Repairing a poly water tank leak

L

Lucky Dog

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I have a very small leak in one of my poly water tanks. It's a drip right at the point where the mold is injected. I have attempted a repair with a JB weld product made for plastic. But, what happens is when the tank is full, the sides flex out. The JB weld stuff does not flex and it cracked and allows the drip to come through the crack.
I was thinking about carefully grinding off the JB weld and going back with a a West sixten type epoxy.

I was also considering West G/Flex epoxy which is supposed to flex.

Any suggestions?
 
Good idea captain Bill that should repair the tank.
If the sides flex too much you might want to think about upgrading the tank to a thicker Poly or building a cage to keep the amount of flexing/ buldging to a minimum.
Bill
 
Coon Ass leak repair: Take stainless steel machine screw of say 3/8" (D) X 1" (L) with a big chunk of gasket material on the head and drive it into the leak. If the leak stops you are a hero. If the surrounding tank surface crumbles you are a zero. At that point renew tank.
 
The material you used is too weak. A straight epoxy resin is 2X stronger, and more if reinforced. Scuff. Wet, use any liquid epoxy resin. Then lay a small tissue over (1"), wet out. Lay another 2 larger. Wet out. Done. The tissue stops sagging, allows "thickness", and adds a little strength. One strength item I found was JB Weld (steel filled) 3900 psi, and epoxy resin 7300, tensile. The JB Weld plastic was much lower.
 
Poly tanks do not take adhesives very well and they flex. That is why professional repairs are done by welding the leaking area with poly.
 
Yup, as Capt bill said, HDPE(High density poly-ethelene) ia like nylon ans nothing sticks to it. The only way is to melt HDPE into the crack or leak. I've been doing it for some years. I use milk jugs and cut them into 1/" wide strips and light them on fire so they start dripping molten plastic. Drip the molten plastic where the leak is. DO'T let the plastic repair site burn and blow out the fire on the plastic strip if it gets bigger than an inch.

If the leak is in the injection site and there happens to have had a 'suck back' which causes the injected plastic to suck back up the injection nozzle, there will be an inverted cone on the inside. You might have to let the dripping plastic burn a touch longer on the repair site to get the molten plastic spread out. Gotta be careful cuz you can melt a hole thru.
 
Personally I wouldn't waste my time trying to repair with adhesives. I have a plastic welder and I would maybe use that, it's the one thing that might work. Very good chance you still get to replace the tank because you can't remove the cause of the failure.
 
The plastic welder looks interesting. It is right at that inverted plug at the injection site. The reinforced epoxy looks like a possibility. Tissue, who would of thought it?

Yikes, you're right the screw method would definitely be hero or zero.

I'll grind off the old patch and take a close look at what I have after that. I hate the replacement option, I have to pull the genny to get the tank out. Otherwise, I would do that in an instant. I'll do the screw before that. Fortunately, it is 1 of 3 tanks and it is isolated, it would just be 40 gallons less capacity.
 
I'd try the screw option but I'd drill the hole to the appropriate size first, to relieve stress from the screw.

Another option would be to install a small stainless bolt from the inside with a rubber washer. I'd drill the appropriate sized hole and glue a few feet of string to the end of the bolt. Then remove the fill connection, drop the string in, and fish for it through the small hole with a coat hanger. Pull the bolt into the hole, add another rubber washer and a nut and you're done.

I've used this procedure installing fittings in 55 gallon poly drums, and it works well. It won't strip out, either.
 
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