help - plastic welding polyethylene

Submitted: Wednesday, Dec 17, 2008 at 22:45

ThreadID: 64359 Views:7572 Replies:7 FollowUps:1

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uneekwahn

greetings all,

i picked up a 55ltr Boab poly water tank at an auction last weekend and unfortunately didn't check it well enough prior to bidding.

got it home and found a nice crack in the thread for the tap.

a friend suggested I try some sikaflex, which I did, and even before buying it, I knew the pack said it wouldn't bond to polyethylene, but thought I'd give it a try anyway. clearly the pack was right and it didn't bond :)

can anyone suggest either another product that WILL bond and seal it or suggest a place in Perth that can do plastic welding at short notice (ie, tomorrow) before I go to Jurien bay for a few days first thing Friday morning?

Cheers,

Jason.

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Reply By: Star Bug - Wednesday, Dec 17, 2008 at 22:54

Wednesday, Dec 17, 2008 at 22:54

I have been in the plastics manufacturing industry for over two decades and nothing will stick to PE. Well very little. To make a sound and lasting repair I would get it heat welded. If I were you i'd forget all the glues. There are heaps of places around perth. Just check the yellow pages.

I have delt with one in the back streets between the Casino and the GF freeway. They were OK.

AnswerID: 340189

Reply By: Michael ( Moss Vale NSW) - Wednesday, Dec 17, 2008 at 22:55

Wednesday, Dec 17, 2008 at 22:55

Polyethelene is difficult to weld, when melted it goes waxy and is hard to knit the parts or crack, even with a filler or a sliver of the parent material. Maybe a pro guy with the proper heat gun and gear, you could ask if its a go. Otherwise you could make the gap slightly bigger and try the original Araldite, the slow curing stuff, making sure the glue goes through the crack to the other side, roughing up the areas you can get to with emery paper. Polyethylene is very difficult to fix, but worth a go!! Michael

AnswerID: 340190

Follow Up By: Michael ( Moss Vale NSW) - Wednesday, Dec 17, 2008 at 23:01

Wednesday, Dec 17, 2008 at 23:01

The other option is to cut the cracked thread out, buy a ridgid PVC fitting to replace the tap thread, something slightly bigger with the same original thread size is quite possible, with a backing nut, make a rubber washer and fix that way.., the original thread would need to be in a flat area to work properly. Michael

FollowupID: 607799

Reply By: uneekwahn - Wednesday, Dec 17, 2008 at 23:15

Wednesday, Dec 17, 2008 at 23:15

i'll see if I can find any places that can try to weld it for me tomorrow otherwise it'll be back to the trusty 20ltr jerry cans for this trip and get it repaired when I return :)

thanks for the advice so far!

Cheers,

Jason.

AnswerID: 340193

Reply By: Member - Duncan W (WA) - Thursday, Dec 18, 2008 at 00:47

Thursday, Dec 18, 2008 at 00:47

Jason there is a place in Belview on or near to Clayton street. Got the name somewhere here but can't lay my finger on it. Company specialises in making Poly tanks to order and they weld as opposed to injecting.

Dunc
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AnswerID: 340202

Reply By: Roughasguts - Thursday, Dec 18, 2008 at 03:17

Thursday, Dec 18, 2008 at 03:17

I bought a 1000 litre square plastic storage tank and that leaked at the tap as well. Any way first thing I tried didn't work but the long cure Araldite did and that was over a year ago.

Just a bit of a scruff up with the Dremmel and widen the crack a little and that was it.

AnswerID: 340203

Reply By: Cruiserman1961 (QLD) - Thursday, Dec 18, 2008 at 08:11

Thursday, Dec 18, 2008 at 08:11

Good day Jason,
the only thing you can really do is to get it welded up professionally with a suitable hot air heat gun or Drader and then re-cut and re-tread the fitting. If you are really lucky and you have a halfway even surface about an inch around the fitting you can get them to spin weld a polyethylene socket on the outside. This is done with a tool which attaches to a router. the router spins with 1000's of revolutions and melts the tank and fitting together by friction.
Any sealant or glue is pointless on a transportable tank i am afaid.
Have a merry X-mas and happy holidays mate:)
Cheers, Udo

AnswerID: 340219