Thread: Cracks and leaks in plastic water tanks

These tanks, made from low density polethylene, are normally welded with a special plastic welding gun. It's a bit like a hot melt gun.

I have a 22500 ltr tank that developed a crack at the top, reported it to the manufacturer, they came out and welded it. Been "as right as rain" ever since.

Thanks Big Shed (no wonder things are right as rain up your way).

No incentive for me to rush back to the manufacturer, but I am interested in your discussion. A friend had a go using polystyrene in a hot melt glue gun. Its just in an awkward spot and difficult to get to. The result was not great (and still leaks).

I see the problem more getting some product to adhere to the base material. I had a go using some polytyrene sticks from Bunnys and a hot air gun. Once again mixed results. I really need a product we can smear onto the surface, possibly use under a patch screwed over the crack (join).

Dave

Plastic welding is done pretty much like this:

http://www.youtube.com/watch?v=UNa3Txagma0

I have successfully used an old soldering iron, but it's not as clean a process as the temperature controlled hot air welder.

If welding, you've got to use the same material for the filler rod as the parent material - you can usually scrounge some off a flange area - otherwise there's a good chance it'll crack out at some point in the future. Actually gluing polyethylene successfully is one of those 'really hard' jobs.

You could try one of the Bostic Urethane glue/sealants . The urethane glues stick like the proverbial to the balnket and remain a bit flexible .
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Applicable Standards

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• CARB and OTC-Compliant
• VOC: 105 g/L

This one comes in a tube to fit a caulking gun