OT: Repairing poly storage tank

Local hardware store has a 2000 gallon water storage tank with a forklift injury; fork stuck through the side. All we can find says the
material is "poly". Poly what, I don't know.
Before I make an offer, I'm looking at the likely hood of repairing it. I know I could patch it with a couple of pieces of metal, an old inner tube and some bolts. I prefer a little better looking repair. More on the line of restore.
Suggestions on repair? Keep in mind it will hold potable water for household use.
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On Wed, 04 May 2005 05:05:42 GMT, Andy Asberry

Material is usually rotomoulded HDPE (Polyethylene) - think of old milk bottles. You may be able to plastic weld it, but the strength of the repair is unknown and there is a fair amount of force (head of water) on it. Might be easier to replace it? Geoff
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Andy, A local company supplies and fabricates plastics. They have a welding system for just that purpose. Contact a similar business in your area. They should be able to make the repair easilly.
Bob
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Andy Asberry wrote:

One thing, Andy - forget all about using glue. I searched once for a glue that would bind to plastic tanks. Forget it. - GWE
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On Wed, 04 May 2005 06:33:09 -0700, Grant Erwin

Loctite Prism 401 with Prism primer 770 has a 500 psi shear strength on polyethylene. It sticks pretty good. Loctite 330 only has a 150 psi shear strength. I don't know about tensile or water resistance. I've used both adhesives with good results. But not on water tanks. If I had to repair this I'd make a patch that fit inside and use both adhesive and mechanical means of repair. Maybe even weld repair on the outside. It's not gonna leak until full and that's when it's hardest to repair. ERS
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On Wed, 04 May 2005 05:05:42 GMT, the inscrutable Andy Asberry

Were it mine, I'd pick up one of the plastic welders either from Eastman or HF, and I'd take a sample to send to a plastics mfgr (or the manufacturer, if their name is on it) for testing. They could sell me a panel I could weld on so it would hold water again--without using any glues which might leach chemicals into the water.
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spake:

What about a pair of stainless steel plates, 2 gaskets and some bolts? Pat
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Some day, I'll read all the responses before posting the same thing someone else has. Today obviously isn't the day that that starts. Great idea, Pat!
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On Wed, 04 May 2005 05:05:42 GMT, Andy Asberry

I have a poly water-storage tank (underground, looks like a septic tank). Before I got around to burying it, the wind blew it down into a canyon. That or the retrieval caused some cracks in the reinforcing channels (material is fairly thick in these areas). Tried kneadable epoxy and jb weld, both only lasted months. Called the manufacturer, they sent (for free) some strips of the original material and instructions on how to melt the strips into a repair. I used a small butane torch, repairs are now about 8 years old. If your tank is the usual cylindrical version, the material at the puncture is probably fairly thin. So you might get the manufacturer to supply enough of the original material to do a patch. Worst case, rivet a patch of aluminum on the outside, melt plastic over the gash and the rivet heads. If the manufacturer isn't helpful, you might be able to trim sufficient repair material off the flange on the hatch etc.
Wayne
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Can you use it as a feature, maybe for a dump spout or something? Something like a firetruck tanker dump valve?

Sandwich of metal, butyl, tank with hole, butyl, and metal? Check for food-safe sealants of course. But if you can make it into a useful outlet from the tank, it solves two problems for you.
Dave Hinz
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Late entry: I'd weld it, and support the welded patch (and perhaps a stainless cover plate) with tensioned stainless bands that encircle the tank and embrace the patch. Weld provides the seal, steel provides the strength.
There was an article in a recent HSM about using the inexpensive HF plastic welder. From reading that and then trying a few welds, I'd expect to get a patch that doesn't leak but wouldn't bet on it having the strength of the parent material.


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