Leak in poly prop tank

Poly Prop or Polyethylene? HDPE is almost impossible to glue. PP slightly easier. Either way I'd be thinking of a weld. Depending on location of leak and size you might be able to weld it with a basic soldering iron and some of the same plastic (I used a toothpaste tube cap last time I welded a HDPE hull on a dinghy!) If its near the bottom of tank it will be under higher pressure and so the weld may need to be 'better' and you may need a proper plastic welder...

Good luck reaching it...
 
catmandoo: you first need to ascertain what it's made of: could be polyprop, HDPE or even LDPE. The welding material must be like for like. If you're very lucky, somewhere on the tank may be marked the code for the material. Many sites carry the code info, such as this: http://i.stack.imgur.com/Il1NP.png

Agree with others that satisfactory glueing, as opposed to welding, is near-impossible.
 
I agree that welding is likely to be the way to go though I think you need a good hot soldering iron with a few watts behind it. I have a Weller "Therma-Boost" which is a general Heat Tool which comes with several "bits", including a soldering bit and a kind of knife bade (which also cuts rope - just!) and heats with either 30W or 130W when you squeeze the trigger.

Or why not give Tek-Tanks a ring (01420 520830), I am sure they would be able to advise...........

Paul
 
What about painting the inside of the tank with a water based bitumen. There are a number of products on the market but maybe this could be suitable

Flexoseal
Products ▸Waterproof & Sealer▸Flexoseal

http://www.phoenixpaints.com.au/products/waterproof-sealer/flexoseal/

https://www.youtube.com/watch?v=xn9xmKsPsW4
https://www.youtube.com/watch?v=nukTMMB4eu8

DynaGrip Plastic Tank Repair Kit
Is this product for you?
If you want a quick and easy way to carry out repairs on a variety of plastics, from automotive-use to water tanks, the DynaGrip Plastic Tank Repair Kit could be what you need. It can be used for making permanent repairs on petrol and diesel fuel tanks, radiators, 4WD holding tanks, and is NSF certified for use in drinking water tanks.

http://www.supercheapauto.com.au/on...Tank-Repair-Kit.aspx?pid=1955#Recommendations
 
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as noted, you must identify the material precisely. Heat welding is the way to go as you will not be able to do diathermy.


Lots of HDPE, LDPE welding strips on ebay, and you need a heat gun with a precise temp and air volume control.

I have a Leister for farm spray tanks and other work, and their site

https://www.leister.com/en-gb/plastic-welding/downloads

is full of excellent advice and videos. Also on Youtube.

However you will need access to the inside of the tank, having identified the location(s) of the leak.


I do recall Giblets and/or Alfie recommending a plastic adhesive for certain plastic plumbing products; perhaps worth an email ?
 
I had a slow leak from my HDPE tank - fortunately it was reasonably easy to get it out of the boat and I then could see where the water was actually leaking from. In my case, it looked as if the tank panels had originally been held together with nails or staples before being welded. The nails had rusted and water was dripping through the places where they had been. I enlarged the holes slightly, put some HDPE shavings into the holes and melted them with a gas fired soldering iron, adding shavings until the holes were full. It was very easy. I was able to shave some material from elsewhere on the outside of the tank, hence no doubts about having the correct plastic. No leaks since (>8 years now).
 
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Unlikely that the tank is Polypropylene. The preferred material is PE Polyethylene.
Both materials have in common that no glue nor adhesive or paint sticks to it.
So your only solution is heat and pressure with a correct gun ( the Leisters are the best in the world ).
People making lab equipment have the most experience. Maybe you can borrow a Leister from them.
You can train on a PE sheet material before you fix your tank. Hope that the leak is accessible for you.
 
You can use solvent weld cement for patches, get a sheet of PE for a patch and apply the solvent weld to both tank and patch, apply pressure whilst it goes off. I doubt that it would work on split welds unless just a weep. Probably the stuff sarabande refers to in post 7
 
Fendant

Now I am utterly confused because I have often glued plastic. Whether the plastic is poly ethylene or polypropylene I wouldn't be sure. Why wouldn't this glue work or am I missing something?

Loctite® Plastics Bonding System

Loctite® Plastics Bonding System is a two-part cyanoacrylate adhesive that sets in seconds and develops tremendous strength with just one drop. The activator primes hard-to-bond surfaces such as polypropylene and polyethylene. Loctite® Super Glue Plastics Bonding System dries clear and sets without clamping. It is resistant to water, most chemicals and freezing temperatures.

Recommended For

Repairing figurines, costume jewelry, cameras, toys, metal car parts, wiper blades, rubber seals and O-rings
Bonds leather, cork, paper, cardboard, wood, chipboard, fabric, metal, ceramic, rubber and plastics such as Plexiglass™, polycarbonate, polystyrene, PVC, polyethylene and polypropylene



View attachment 57260
 
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Hi Coopec,

the problem of PE and PP is that they both have absolutely inert surfaces ( chemically they are simply high molecular waxes ).
The only way to get a bond ( inferior ) is when you succeed to oxidise the surface. You have to start with a thorough cleaning process with chemicals not sold to private individuals ( highly reactive acids ) and then use a pretty agressive primer in a given temperature and humidity window ( as in above Loctite spec ).
It might work for a non or light pressure load on a water tank, but I would not use it for a structural joint.
One problem with cyan based adhesives are the different thermal expansion coefficients between PE/PP ( high ) and a thermoset resins ( low ).

Hope this helps
 
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So is a mechanical rather than chemical bond the answer? If you could drill a round hole and plug it....but then the leak will be on an edge or corner, or where there is moulding detritus making it uneven.
 
Unfortunately a mechanical solution is not the answer. PP/PE have relatively low compression strengths and tend to creep under load. This is the reason why rotomolded tanks have metal inserts for the inspection hatch and the fuel sensor holes.
 
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