Plastic welding:

[speeder]

Anyone here have any experience welding plastic? Maybe I'm just imagining this but I could swear that I've seen thick plastic welded just like metal(?)

Here is the deal; the fresh water tank in my RV has a broken off tube where the water fill hose connects. It's a clean break. I was thinking about cutting an access panel in the top of tank, fitting a new tube fitting from inside w gaskets and then closing back up the panel. Since it would be on top, leakage from the access panel is not a big concern but it still needs to be tight to keep contaminants out, etc.

I suppose that I could just epoxy it back together but if it can be welded, it seems like that would be better. I'll get photos tomorrow to better illustrate it, rig is in the shop right now getting windshield sealed, (again).

Thanks!

[Zeke]

Some plastics weld and some don't. Your water tank is likely on the list of weldable plastics. But first you must determine the nature of the tank so you can use the correct filler rod.

[speeder]

Thanks. Picture that thick white, semi-transparent stuff. That plastic.

[flipper35]

Call a local body shop. Good ones have a welder.

[908/930]

As Zeke said, need to know material, probably made from polypropylene or polyethylene? I have used a hot air welder on acrylics, getting the temp right to not get bubbles in the weld area was hard part if I remember, that was some time ago, the polypropylene or polyethylene should not have that problem. How thick is the tank?

I do not think that epoxy will work.

[71T Targa]

I used this process to repair a huge crack in my HDPE canoe. It's not pretty, but it's solid and water tight. I used the HF plastic welder and a mini torch to help keep things at temp.

[cabmandone]

Just hit it with JB and call it a day. Bout the only thing JB won't stick to is that stuff made with soybean oil. Nothing sticks to that.

[GH85Carrera]

Yep, I have had it done.

The film processors at we used for years were made of a grey plastic that had a soapy feel, and no glue of any sort would stick to it. We had to hire a guy to come plastic weld one tank back up after a former employee managed to burn the building down when he left a 1,000 watt heater unattended.

It was much like metal welding, just different material.

[911boost]

I had a leak in the fresh tank on my travel trailer. Really odd sized tank that I could not find a replacement for.

Look up "spin welding", I found a local place that could put a patch in. Most RV tanks come without the hoses points attached as they vary by model. If you have the tank measurements I can send you the name of the place my tank was made, they sell a TON of replacements just not one for mine.

[cabmandone]

Just get in and drive it down here. I'll take it to my nephew. He'll fix it. They weld that thickness on a regular basis. But I'm not givin ya any of my beer!

[speeder]

Thanks, guys. I'll get pictures up tomorrow and it will all make more sense, including to me.

[petrolhead611]

I have welded loads of PVC as a cover maker an polypropelene, to repair plastic Wheely bins(dumpsters) There are two methods that I have used. For PVC you have a choice of using PVC cement on a lap joint using a pressure roller thereafter ( usually used for joining plumbing fittings and requires no real skill: or 2 KW hot air lap welding using a hot air gun( make sure it has a variable temperature control) blowing the hot air between the two sheets and rolling the seam with a polyurethane pressure roller. For polypropolene use the hot air gun and some polypropelene scrap as a filler rod ( get everything up to temperature and do a few tack welds to hold the patch in place the seam weld.

[LEAKYSEALS951]

Your truly washed a pair of pants once with some sharp screws in them, which promptly fell out of my pants, got caught in the small holes in the bottom of the machine, and cut through the washing machine tub while it spun.

This tub was the "non bondable" plastic. I disassembled the plastic tub to gain access, and used a simple soldering iron like a hot knife to weld it. It's held for about 6-8 years so far. The trick was to treat the plastic like welding a bead, meaning both sides had to melt into one another to get a good bond. Once cold, it was still flexible. Ithink I even added in some extra plastic like a welding stick.

(I'm guessing it's like the video posted above- I didn't watch it yet..)

[Bill Douglas]

Denis I've had some luck recently with a plastic fix a bit like yours.

I used a soldering iron - not too hot, and carefully melted the plastic from left to right etc over the break. It worked quite well. So it's hot enough to melt it, but not so hot as to burn it. then maybe some araldite over the join to water proof it.

[JJ 911SC]

Sadly it's still in the original wrapper, circa 2015...

[dad911]

I fixed a polypropylene water tank with scraps and a propane torch. Pure rube-Goldberg luck.

Also patched one with a square of aluminum, gasket, and stainless bolts.

Originally Posted by speeder

.......
Here is the deal; the fresh water tank in my RV has a broken off tube where the water fill hose connects. It's a clean break. .......

If it is a clean break, can you use a bulkhead fitting and adapt the fitting to your filler hose?



Or a gasket and a flange fitting:

[john70t]

As corny as it seems, this infomercial product looks like it works. Not sure about the penetration.
(Dental type UV-cured bond glue.)

Bondic Review #2: Bondic plastic weld review

(skip to about 12:00 where he fixes a plastic tank full of water in only seconds)

[javadog]

You gotta identify the plastic first. Some don't play nice with either welding or epoxies.

[Bob Kontak]

Originally Posted by 71T Targa

I used the HF plastic welder and a mini torch to help keep things at temp.

I've had very good luck with the HF plastic welder.

The mini-torch is a great idea as the neck of the heat pad eventually bends backwards when you try to put pressure on it to drive more heat into the work.

[MBAtarga]

I've seen video (very likely youtube) of folks using the cheapo horrible freight tarp fabrics as the "raw" material to weld broken plastic objects.