poly tank repair

[dadof4]

i need to repair a 3 inch long crack in a poly tank.when i spoke to a poly welding company they said they said the welding wasnt always sucessful.has any one any methods i can try.

[Big Shed]

i need to repair a 3 inch long crack in a poly tank.when i spoke to a poly welding company they said they said the welding wasnt always sucessful.has any one any methods i can try.

Don't know any other way of welding a poly tank. One of our tanks, a 22000ltr Polymasta developed a crack in the top and it was fixed under warranty, that was about 4 years ago and it is still going strong.

Where in the tank is the crack?

[Claw Hama]

If you have access to both sides of the crack you could just bolt a metal plate to it with nice big washers on one side. Slip a lenght of flash tack or something food safe under the plate to seal against the crack once the bolts are tightened.

[BobL]

i need to repair a 3 inch long crack in a poly tank.when i spoke to a poly welding company they said they said the welding wasnt always sucessful.has any one any methods i can try.

They will generally say that because they probably don't want to keep welding it over and over again if it does not take. This a somewhere between a rock and a hard place for any company, 9/10 times it will be OK but that 1/10 times will create more than the other 9/10 work so unless you bought the tank from them they will try to avoid it.

Where is the crack, if it is on a seam or angled corner or in a place that cannot be cleaned or accessed properly, or can only be welded on one side the likelihood of it work goes down a lot.
Maybe an independent plastic welder to do the job.

[BobL]

If you have access to both sides of the crack you could just bolt a metal plate to it with nice big washers on one side. Slip a lenght of flash tack or something food safe under the plate to seal against the crack once the bolts are tightened.

This will work sometimes for a long while but if you have access both sides you might as well get a plastic plate of the same material welded on both sides

[Buzza]

Poly does not weld at all well if it is to be under pressure. A shapr wack will reverbarate the contents, and the welds will always let go with an audible crack

One solution, is to purchase an inner liner. These are available for about $250.00 or so. Depending on your supplier and the size of course. They are essentially, a plastic sheet made into a bucket shape.

The suggested solution, e. g. sealing the crack wih a plug can work as the other answer suggests, but I would utilise some neophrene (sic) on the wall inside and out, with the timbers over the top of them. Once the neophrene is squashed under pressure, it wll seal. Source neoprene from an old wet-suit or some runners that have been tossed away.:)

I have just gone through the dramas of a leaking poly fish pond of 500 litres, and a rusting galv water tank. :C

[prozac]

Poly tanks do not weld well.

Drill each end of the split to "stop" it. Just a small size drill, don't go bananas. Claw hammer is right on the button with his advice of using two plates bolted through. Instead of using SS for the plates perhaps two plates cut from a kitchen HDPE (High Density polyethylene) chopping board would be less likely to stress at the edge contact points? I don't know if Sika make a product suitable for potable water but an alternative might be soft butyl rubber which will squeeze to form a tight seal when some pressure is applied via the HDPE plates.

prozac