Fixing air tank

[Bruce Koch]

Does anybody know of a way to fix a hole in an air compressor tank?

[Mike Henderson]

Unless you made the hole, one hole is just the beginning. If the hole is caused by rust, I'd buy a new tank now before you spend a lot of time fixing this tank.

But if I had to fix such a hole, I'd use welding equipment because I have it. If you weld it, you have to vent the tank (and keep it vented) because as you heat the tank, the air will expand and push your weld back at you if it's not vented. If the hole is in an existing seam, I would not repair it - I'd definitely buy a new tank.

But I don't like "fixing" anything that can explode in use. An air tank under pressure is a bomb - you want to make sure it's well within it's design parameters, and sufficient rust to eat through the tank means a lot of the design margin is gone.

Mike

[Jim Rimmer]

Unless you made the hole, one hole is just the beginning. If the hole is caused by rust, I'd buy a new tank now before you spend a lot of time fixing this tank.

But if I had to fix such a hole, I'd use welding equipment because I have it. If you weld it, you have to vent the tank (and keep it vented) because as you heat the tank, the air will expand and push your weld back at you if it's not vented. If the hole is in an existing seam, I would not repair it - I'd definitely buy a new tank.

But I don't like "fixing" anything that can explode in use. An air tank under pressure is a bomb - you want to make sure it's well within it's design parameters, and sufficient rust to eat through the tank means a lot of the design margin is gone.

Mike
I agree with Mike. I tried to fix one years ago with JB Weld. I would fix one hole and then I would have another. Finally just got a new tank.
+1 on the "bomb" comment as well.

[Scott T Smith]

As usual, Mike's comments are right on target.

Presuming that the hole was caused by water rusting through the bottom of the tank, rather than just welding up the hole I would seek to make a patch that surrounded the corroded area by several inches and rose an inch or two "above the hole" so to speak. This is because the metal near the hole is usually fairly corroded, and when you try to weld it usually just disintegrates.

Depending upon the thickness of the base metal, I would either use MIG or if the metal was fairly thin - a furnace brazing rod with a tig torch.

[Craig Summers]

The other reason to vent the tank is BLEVE: Boiling Liquid Expanding Vapor Explosion.

Simply put, if you heat a liquid, it will try to turn to a gas, eg Water to Steam. Water will expand 1,700x its volume when vaporization occurs. and at 1,000F it expands 4,000x volume. Doesnt take much water to jack up the pressure on an already weakened and compromised container.

If you dont think BLEVE (http://en.wikipedia.org/wiki/BLEVE) is bad, there are videos (http://www.google.com/#hl=en&q=bleve+explosion+video&aq=0&aqi=g3&aql=&oq=bleve+explosion&fp=a048890d3c90c6fc) out there. Tanks or cylinders that get too hot have been known to split in half and go 1/2 mile .... in each direction. And it doesnt have to be flammable materials.

[Bruce Koch]

The tank is a rol-aire twin tank and replacing the tank is out of the question. It has a good pump and motor. Maybe we can bypass the original tank and add a storage tank as an alternative storage.

[AL Ursich]

I know a guy that used a old 35 gallon galvanized water tank for a alternate storage device. Used a old compressor but failed to add a relief valve. The Pump Motor cutoff was set to 120 PSI.

It exploded and took out all the windows in his wood shop.... He was at lunch.....

Tread Lightly....

AL

[Rob Russell]

You could use one of those portable air tanks as a storage tank - they're not particularly expensive.

I just checked sears.com and they have a reference to an 11 gallon tank at restockit.com for $55 + shipping.

[Gary Click]

Jack up the compressor and slide a new tank undeneath. Repairing or modifing a pressure vessel is dangerous even if you have an understanding of what you are doing.

If you simply must repair or weld a tank protect yourself by preforming a hydrostatic test of the completed system by overpressurizing the tank after it has been completly filled with water to the exclusion of all (100%) of the air in the tank. On second thought, jack up the compressor and slide a new tank under it.

When I work for a large tank building company (CBI) many years ago we would sometimes build large gas receivers called blimps. These are vessels that operate at low pressure (5 to 10psi) but have huge volumes (25' diameters by 90' long). Because of their relatively thin wall, these vessels could not be filled with water and required air testing. During the test the safety exclusion zone was 1/2 mile radius due to the stored energy in the compressed air.

This is not something to take lightly. For an idea of the explosive force of an overpressure explosion, google "locomotive boiler explosions". While not quite the same since the hot water in the boiler flashes to steam when the boiler pressure falls due to the rupture further increasing the compressed energy in the expanding gas, you can get an idea of the destruction a ruptured pressure can create.