Is a Dented Air Tank Safe?

Safety and liability concerns with a damaged pressure tank. November 14, 2009

The owner of our company just purchased an air tank at the local steel scrap yard. One of the legs is crushed and dented the tank in about 3 inches at the weld. He says it is perfectly safe to use, that it can't explode; at worst, it could start leaking. What is the consensus here? I told him I would not use it, too much liability.

Forum Responses
(Dust Collection and Safety Equipment Forum)
From contributor H:
Tanks give volume first, pressure second. Since most air equipment operates on less than 100 lbs, most safety blow-offs are set at 125 lbs. Your boss is correct; it won't explode, but will most likely leak at or near that dent. Any time you damage a cylinder or sphere, you weaken it. Remind him it was in the scrap yard for a reason.

From contributor C:
I would stay away from used and/or damaged tanks. Believe it or not, air tanks can explode when they fail (although I'm sure that's not what happens each time there is a leak). And when they do explode, they become shrapnel. I know of one such event where it killed a person. This would be part of the reason each manufacturer recommends draining moisture from the tank daily.

From contributor P:
Any time steel is bent or formed, its grain structure is changed. This is called cold-working. This area is generally harder and even stronger, but it also is much more corrosion prone. The harder areas will crack first if they are cold-worked too much. Since you do not know what is going on inside the tank, cracks forming, etc., I would scrap it. Old tanks are generally the weakest where the legs are welded on and since most corrosion takes place near the bottom. Chances are it would just start a slow leak, but they do explode and can take the building with them if they are inside.

From contributor M:
I never thought an air tank would explode either, but I saw one that did, and it was sitting in my lawyer's office... That's all I need to know about used, dented tanks.

From contributor B:
Our company always cuts up old tanks before disposal. It's for legal reasons.