THIS is why you must vent your tanks...

[rossvtaylor]

This stainless steel fresh-water tank, blown up like a puffer fish, is an example of what happens if you don't vent your tanks. Hooking up a hose to fill the tank, with water at 50-60...or maybe up to 80 psi, without having the tank vented distorted this heavy stainless steel tank. You can tell where the interior baffles are welded in, which gives the tank it's tri-hump look. A simple vent would have prevented this.

Keep in mind that waste tanks must be vented too, because if you don't they'll vent back through the interior plumbing...forcing stinky bubbles through the P traps.

This stainless tank is in the bus we live in and it's now pretty much permanently locked into place, because the top is bulged between the frame rails. I just replaced the waste tanks, which were next to this fresh-water tank. Our next project will be to hook a vacuum pump line to the stainless tank and, hopefully, collapse it enough to be able to pull it out and re-weld a cracked bottom seam. That should be interesting and I'll post pics when we do it.

 

[A Crafty Beaver]

Also, don't forget that psi is short for pounds per square inch. So if you fill a tank to 60 or 80psi you are exerting a huge amount of force on it. Each square inch of the tank is being pushed out on with 80 pounds of force- it adds up really quickly.

 

[s2mikon]

Y'all missed the point. How else are you going to add capacity?

 

[slowstepper]

Good luck to you. i would be skeptical of being able to pull enough vacuum if the seam is compromised. I hope it works, hate to see you have to cut it out piece by piece

 

[joeblack5]

Nice hydrostatic test. how did the air normally get out when you filled it up...unless this was the first time..if air was still inside then you were really lucky. .Try a shop vac. To pull it somewhat back.

Thanks for sharing.

Johan

 

[musigenesis]

You could try Ye Olde Newcomen Engyn approach and feed it full of steam and then spritz some cold water in. Might go too far the other way but at least you could get it out then.

 

[rossvtaylor]

Thanks all - too many individual comments to address...well, individually...so let me try to get them all here.

This happened before we bought the bus. I knew the tank was puffed and planned to address it later...which is now.

The black and grey tanks were also not vented. Yuck.

The split seam is a small crack, about a 1/4 maybe? Unfortunately, it's right at the bottom on a corner and I can't get in there to weld it. If it weren't for that small leak, I'd just leave the tank as is and relish the extra volume s2mikon pointed out!

The crack/leak is small enough I think I can pull a vacuum okay. I have two large lab surplus vacuum pumps, so I can do better than the little A/C system pumps. We shall see, though.

I like musigenesis' idea... poof...then poof!

I did replace, and vent, the other tanks and installed a Shurflo macerator pump. So, progress.

 

[Simplicity-SKO]

When I saw the photos on my phone it wasn't clear how the tanks expanded, but yeah, that doesn't look good.

Just throwing this out there, if the vacuum trick doesn't work, and the steam/cold water doesn't, what about air bags to push at least one part of the top of the tank down enough to remove it??

I got the idea from watching them use air bags to remove dents in cars.

 

[rossvtaylor]

When I saw the photos on my phone it wasn't clear how the tanks expanded, but yeah, that doesn't look good.

Yup...it blowed up nicely! If vacuum doesn't work, and rapid cooling fails, I'll probably resort to a BFH. But airbags might be an option.

 

[musigenesis]

The split seam is a small crack, about a 1/4 maybe? Unfortunately, it's right at the bottom on a corner and I can't get in there to weld it.

Some gorilla tape over the crack might help, or taping on a small strip of sheet metal so the tape doesn't get sucked through. For the steam the tape would also help since it wouldn't be pressurized steam (although maybe it would be - you do get up to some wild stuff).

 

[Simplicity-SKO]

JB Weld.

If you put a vent in, the pressure will never be that high. JB Weld is pretty amazing if you use the correct one and prep the area properly.

Of course, since it's your fresh water tank, chemical leaching may be an issue???

 

[rebapuck]

Can you cut a hole in the floor below the seam?

 

[rossvtaylor]

You guys with all your oh-so-easy, excitement-free solutions. Bah, humbug. How will I get to see the tank implode if I don't try the harder option?

 

[musigenesis]

You guys with all your oh-so-easy, excitement-free solutions. Bah, humbug. How will I get to see the tank implode if I don't try the harder option?

Fred Dibnah wants to see you try the steam thing.

 

[Bus'n it]

I'd like to see the steam thing too!

Where would I get a custom made stainless steel tank? I have a peculiar design that I need to get the tank in the bus under the bed with a high capacity. I do not want to use a plastic tank due to trust issues with them.

 

[o1marc]

I'd like to see the steam thing too!

Where would I get a custom made stainless steel tank? I have a peculiar design that I need to get the tank in the bus under the bed with a high capacity. I do not want to use a plastic tank due to trust issues with them.

Google search "Custom Stainless Steel Tanks" , large list to choose from.

 

[WilboVIBC]

Its on its way to nice spherical shape.