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REPURPOSING / repairing used water tanks - HDPE - for AP
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Author:  BuiDoi [ Jun 21st, '15, 12:30 ]
Post subject:  REPURPOSING / repairing used water tanks - HDPE - for AP
..
So.. I got a used tank and cut it in half.

The tophalf, identical to the bottom, but has the usual filter hole and overflow hole..

I tried "Welding" a crack in an old wheely bin, but it failed under pressure.. :upset:
So I am thinking of taking a large disk of bin material and bolting it across the old tank 300mm filter hole..

Anyone ever done it with complete success, and any warnings of what fails in time, given that it will then be at the base and under maximum pressure and especially tension..

Planning on using many stainless bolts as the principal mechanical holding method and the a sealant of perhaps a broad gasket of MASTIC, which I assume will forever remain malleable and compliant..

Have you been there and done that??

Peter
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Author:  cathode [ Jun 21st, '15, 14:07 ]
Post subject:  Re: REPURPOSING / repairing used water tanks - HDPE - for AP
HDPE must be "welded" with hot air. I have never done it myself but it does not seem terribly difficult. You would need some matching HDPE "welding rod" that you would melt into the joint or crack in this case.

If you aren't able to heat-weld it, then a 100% RTV silicone sealer would be my best guess. I did have luck getting that to stick to polypropylene which is also a plastic that is normally only heat-welded.
Author:  BuiDoi [ Jun 21st, '15, 15:22 ]
Post subject:  Re: REPURPOSING / repairing used water tanks - HDPE - for AP
Quote:
HDPE must be "welded" with hot air. I have never done it myself but it does not seem terribly difficult.
..
I had intended to split the long lid of the Wheely Bin and cut some rods from the edge, and used them with the hot air gun.. It seemed to work well, but it developed cracks, like heat cracks..
I did wonder if it was because the "Sticks" from the lid were VERY sun-baked and the surface was significantly different to the the base, which melted and flowed whilst the top surface was structurally more solid..

Anyway that is past history, and that bin will be cut down to make a wicking bed..

My preference is to cut a disc to cover the hole and bolt it in place .. Quality RTV was an option..

BTW - I did manage to seal a perspex window to that wheely-bin, using stainless bolts and "Gorilla Glue" as a sealant..
Bolts every 75mm and oversize washers either side
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Author:  earthbound [ Jun 21st, '15, 18:01 ]
Post subject:  Re: REPURPOSING / repairing used water tanks - HDPE - for AP
We did a viewing window i a tank using perspex. Lots of stainless steel bolts and HEAPS of silicon and it's held for many years now without any problems.
Author:  BuiDoi [ Jun 22nd, '15, 08:14 ]
Post subject:  Re: REPURPOSING / repairing used water tanks - HDPE - for AP
earthbound wrote:
We did a viewing window in a tank using perspex. Lots of stainless steel bolts and HEAPS of silicon and it's held for many years now without any problems.


so you seem to support the idea of a cover plate and silicone... thanks...

I suspect that there are many fillers that will work under such tight bolting.. I might try the mastic, as much as a personal experiment..

The gorilla glue worked with my window, but I was concerned for it's use at the bottom, where the pressure is MUCH greater, and the bottom will be needed to bow down to create the desired shape.. ie stretch..

Ill convince myself b4 I give it a go
..
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