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Plastic Repair

07/25/2009 10:07 AM

I have a polyethlene lined shaker tank. There is a plug near the bottom, which has been leaking. We've tried welding the plug, to no avail. What would be the best way to repair this? The tank contains steel shot, and a high ph cleaning solution. We clean brake caliper pistons

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#1

Re: Plastic Repair

07/25/2009 11:44 AM

tried to weld the basin drain plug fitting.

interesting idea. Ahuha

might it ) basin ( be cracked around that fitting ? or a seal worn ?

if that plug can be removed ,, if ? drain basin inspect visually , or some method , from both inside and out side basin ..proceed based upon findings .

buy a new tank , it will improve your reputation locally , adding $$$ to your bottom line. the new tank will also have an owners manual; making the economic investment worth the price of admission .

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#2

Re: Plastic Repair

07/25/2009 2:19 PM

I don't know if this would work in your application butI have had good success with friction welding plastics. I have stuck different types of plastics together with good successes even with ones that were not normally glueable too.

Just for thought heres how I would try to repair it.

If the cracks are right around the plug it self it may be possible to cut out the plug and then tapper the hole so that its a concave shape. The cut a polyethylene pipe fitting or what ever type of fitting it uses to a convex tapper close to the same angle and shape as the hole. Then set up a drill with the right adapters so you can spin the fitting and just press it into the hole. Friction will heat up the plastics to their melting points and the spinning mixes them while smoothing out the two surfaces to an exact match. Once the two plastic are hot enough and mixed properly just let them cool in place and then trim off any excess that was squeezed out during the welding process.

I have found this works with almost every type of plastic and can even bond things like polyethylene to PVC with a strong reliable weld.

I learned this from an old school plumber that used it for making fitting adapters to connect different plastics to each other that don't normally have compatible gluing abilities or just for making the occasional speciality fitting or part.

And yes the plastics experts are likely to have a fit about it but reality says it works anyway!

If it dont, it was aready broken and you at least learned something new!

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#3
In reply to #2

Re: Plastic Repair

07/25/2009 6:14 PM

I just wanted to say that's pretty good. An idea to keep tucked in my skull.

Obviously when heated and swirled the two plastics as liquids flow together and thus intermixed form a new structure and don't need to be glued.

All I can say is COOL!

j.

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#4
In reply to #3

Re: Plastic Repair

07/25/2009 9:46 PM

I read about a college professor with at doctorate in plastics manufacturing thats trying to make plastic alloys by combining plastics with normally non compatible molecular structures into specialty plastics alloys.

Unfortunately I also know a old plumber that was doing that back when plastic pipe was still new to the plumbing industry a few decades ago!

Strange how the 'Smart ones' are the last to figure this stuff out.

Had the plastics doctorate guy talked to his uneducated toilet monkey he may have learned about this 20 years sooner!

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#7
In reply to #2

Re: Plastic Repair

07/26/2009 6:44 PM

tcmtech

Very nice. GA. The result might not last as long as a homogeneous material but it would do the job. I will try it out next time, or do it today and see if it works and how much stress it takes after cooling. Could come in handy one day, Ky.

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#5

Re: Plastic Repair

07/25/2009 10:05 PM

You might consider removing the plug and replacing it with a bulkhead fitting.

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#6

Re: Plastic Repair

07/26/2009 5:46 PM

Plastic welding only works well if the plastic filler matches the plastic workpiece, and even then in my experience the extra heat means you loose some of the properties of the original, often more brittle. There are some 'universal' filler rods, including with fibres, that attach to most plastics and can be used to re-inforce. You can also add mesh or fibres to re-inforce. I did not have any luck with a polythene pressure barrel as the repair always cracked, so if it's justs a drain point then a compression fitted replacement sounds like an option.

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ahuha (1); Jack Jersawitz (1); ky (1); lyn (1); Mikey63 (1); tcmtech (2)

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