Looking for a spray on sealer

I have a need to seal a plastic tank used for storing non-drinking water. Ideally something that is a rubberized sealer that sticks to everything. I have tried marine epoxy, but it didn't stick to the plastic for very long. I need to seal the leak from inside. Anybody have a suggestion?

FWIW, I just bought a tube of this "heat activated plastic weld epoxy" yesterday. Sounds promising, but I haven't tested it yet.

http://www.solder-it.com/shop/item.aspx?itemid=224

There are a few options:
Install a "bulkhead fitting" over the leak. This is a mechanical solution and can be good if you need another vent or drain anyway. You have to have access and the area usually has to be either flat or only slightly bowed.

There are bladders that can be inserted into a tank and used independently of the ability of the existing tank to hold water. There is also a resin impregnated version that you insert, blow up with compressed air and allow to harden. These get used a bit in boats where an old tank fails and removing it means disassembling the whole thing. They aren't cheap but they work pretty well.

If you can get to the spot easily you may be able to weld the plastic. Plastic welding uses a hot air gun and a rod made of the same material as the tank. If you're really handy you can do it yourself. If not, or you don't want to risk it, you can hire a guy. Any shop that deals with custom plastic assemblies will know someone. Down side is that welding can be iffy on some plastics, less so if you are experienced, and in some cases older plastic has lost so much plastisizer and cross-linking that welding is impossible because the strong weld material breaks off the older/weaker plastic.

Glues, paints and coatings generally don't stick well to common plastics used to make tanks. Generally mechanical patches work better. I've seen a patch on sewage tank on an RV last for decades. They drilled out the small hole, installed a stainless steel bolt with a stainless fender washer coated with Boatseal on both sides of the tank material. They dropped it in place through a handhold in the top and just snugged it up. Coming back to tighten up the nut after the sealant had hardened. The bolt and washers hold the pliable sealant in place so it doesn't have to stick. In essence it is simply acting as a form-fit gasket.

Any/all of those have/might work but all of those have failed. A lot of times they fail because people try to rush things and are not meticulous about doing it right. Other times such repairs are a lost cause no mater what you do. Often it is best to replace the plastic tank. They aren't terribly expensive. If the people who installed it were good they arranged for there to be some way to get the beast out without disassembling the world to get to it.

Doug, Did you find that someplace retail, or did you order on-line?

You may want to look at the JC Whitney.com catalog,They used to have a sealer that was poured into dry Metal gas tanks,& Then when cured it was better than the metal alone,often used for Race cars/off-road vehicles.It may be possible for Plastics use,It's worth a look either way,Good Luck!

Goop?

You're probably going to need to know what kind of plastic your tank is made of. Adhesives and sealers often react chemically with certain plastics if not compatible.

If the tank has a brand on it, maybe you could track down the mfgr and ask for info and advice.

Sue

I bought it retail at a Canadian hardware chain. Don't know who carries it in the US, but somebody probably does since it's made in USA.

(I also bought their low-temp silver solder paste for field repairs and putting tabs on batteries, which can be destroyed by regular solder. This stuff claims it only needs Bic level heat to activate.)

What kind of plastic is your tank made of? High density poly? Maybe I can do a test for you.

Previous comments about plastic welding are valid also, though I have seen some problems if the weld is exposed to a lot of UV.

Here is the tank. Thanks Sue. Great advice. I'm going to see if I can get a replacement tank. But a quick fix is still useful.

http://www.hdhudson.com/product-search/product-details/?id=38

If the top of the tank is accessible you might look into buying "inspection ports". These are usually 4" diameter fittings that act as a way of inspecting and cleaning out the interior of a tank. These are designed to be mounted in the flat top surface of a poly tank and are pretty easy to install. They are essentially over-sized bulkhead fittings with a 4' diameter plug. They work very well on top of the tank but are generally deemed unsuitable for the bottoms or sides.

Install one of them and you can gain easy access to make repairs from both sides. Those ports are available at chandeliers and stores catering to boating and sailing enthusiasts. Some RV places catering to people doing repair work may also carry them. Poly tanks are commonly used on boats, both power and sail, and RVs. They are commonly used for diesel fuel, drinking and waste-water.

Garly_, I had a look at the link. I doubt any weld, goop, or mechanical repair would stand up in a pressurized plastic vessel. It's almost certainly a waste of your time and money. Plus there is the risk of a leak affecting the operator -- small if it's dilute Roundup, but considerably larger if it's a full-blown pesticide/insecticide. My honest advice is to replace or abandon that tank. It's just not worth it. Sorry.

It's not pressurized. I think it is worth a couple bucks worth of glue to try to fix.

My mistake! If it's not pressurized, it's worth a try.