tank repair

[BarnYardCamp]

When I installed my fresh water tank I didn't realize until later that I had pinched a 12v wire. To free the wire, I pried up on the tank and may have damaged the tank. The tank is built in, to remove it would be a major PIA as I would have to disassemble the bed.
I barrowed a "Boro-scope" to look inside the tank. i can see whay I believe to be a small damaged area. I was thinking about buying some slow set PVC/plastic pipe glue and pouring it through a tube onto the damaged site. Very small, maybe 1" long.
I figure that PVC cement would be ok since it can be used in water pipes.
Any thoughts on this? Has anyone traveled this road before?

 

[BarnYardCamp]

I've given this some thought and have decided to pull the tank out. The primary reason is that even if I could repair the damage, I'd still worry about it leaking. So today, I'll start dismantling the bed. Once I get started I'll be able to determine if this is the best course to take. Plan "B" would be to leave the bed in place and to cut the tank into little pieces then order a new slightly smaller tank that would fit with the bed frame in place.

 

[TheHubbardBus]

I wouldn't be confident of your initial repair plan if it were my tank. For one, PVC cement is made for PVC, and while I suppose it's possible your tank is too, I kind of doubt it (PP or PE would be more common materials). Even if it is, when you use PVC cement to join plumbing pipe/fittings, it's essentially 'melting' the two parts together through chemical means. Without any 'filler' PVC, it's simply not going to work. It might stick, but I wouldn't consider it to be watertight, especially considering the consequences should it let go.

If I were you, I'd either have it plastic welded, or install a fitting + plug at that location. I believe spin-welded bungs to be the most robust solution for a fitting, assuming your tank is suitable, but as far as I'm aware you need special drill bits + some measure of experience to do the job. We had to have an extra bung placed in one of our tanks, but after pricing out the bit needed to do it, I ended up bringing it to a local biz where plastic tanks is all they do. After watching him do it, I'm glad I made that choice. I'm sure I could achieve the same with some practice, but I'd hate for attempt #1 (or 2, or 3) to be on something I cared about.

You could always go with a gasketed bung/bulkhead fitting, but that assumes you have the ability to reach the back of the fitting through the inside of the tank. But even if you do, if spin-welding is an option, I think it would have a greater chance of long-term success.

I've never welded plastic, but I know folks that do. You could probably bring yourself up to speed on that pretty quick using a suitable iron + proper filler material. Or press the easy button & find someone local who's experienced. Doubt it would cost much.

 

[BarnYardCamp]

To do any of that I'd have to remove the tank...so, it's coming out today. Most likely in bits and pieces.

 

[BarnYardCamp]

I called tank mart and inquired about repairing the tank They said that nothing will stick to polyethylene so the only way to repair it would be a plastic weld.

 

[Danjo-SKO]

If the crack isn’t too big you can get a spin weld fitting (plug) installed. Maybe you can get lucky and find someone locally. Try Camping World.

 

[BarnYardCamp]

I got the tank out this eve. From the outside, I see no damage, no cracks. Is it possible to have cracked the inner layer? When I looked inside the tank with the boro-scope, I definitely saw what looked like a crack on the inside.

Anyway, right now the tank is half full of water and sitting in the bed of my utility truck. I'll check for leaks tomorrow.

 

[TheHubbardBus]

Maybe you got lucky & were wrong about what you saw? Fingers crossed that's the case.

There shouldn't be any inner layer AFAIK. It should be just one continuous thickness of PE. If you cracked it, I'd expect the crack to run full-thickness, but that's more from an intuitive feeling than anything. I can't say for sure. Just seems unlikely a crack, if present, wouldn't run all the way through.

Is there any chance the build-up of hard water deposits or anything else that ended up deposited on the inside could be responsible for the appearance of a crack? I could see that happening, especially combined with the generally poor res of many tools like you're using.

 

[BarnYardCamp]

yes, the tool I used to peer into the tank was certainly on the low end of the quality spectrum. Basically, a tiny camera with a tiny flashlight attached via flex cable to a hand held controller that had a 3 x 3" screen....powered with 4, "AA" batteries.
Anyway, the tank sat over night, about 1/3rd full of water. No leaks. I plan to re-install it this eve after the heat of the day begins to subside.

 

[TheHubbardBus]

What ended up happening, Barnyard? Did it end up being good to go?
Fingers crossed for you.

 

[BarnYardCamp]

After a lot of work and some profanity, I removed the tank. Once I had it out, I found no visible damage so I let it sit overnight with water in it. No leaks so I re-installed it. Now I'm waiting for more motivation to show up so I can get back to working on the bus. DC/DC charger install in next on my list.