What happens when an air compressor tank rusts?

[Glen Blanchard]

Let's say that I have an air compressor that I have not really treated with lots of TLC. Let's say that I've had it for about 15 years and have only drained the moisture inside the tank a few times. Now let's say that it's rusting inside.

What eventually happens? Does the rust eventually eat through and the tank begins to leak, politely letting me know it's time to buy another? Does it blow up and take down everything within a one mile radius?

Just wondering on an academic level. Certainly none of this is accurate in my particular circumstance. Nope. I'm sure my compressor loves me. I'm just a curious guy.

[Brian Henderson]

It depends on the amount of damage and how it's laid out. You can certainly have a blowout but more than likely, you're going to get a small leak first before it gets to that point. You can always replace the tank if the compressor itself is still good.

[Keith Outten]

This is one of those situations that you cannot afford a failure. Many years ago a 20 gallon air compressor ruptured here in my local area and totally destroyed a two car garage. It blew all four walls out and the roof came straight down. The owner had just left his garage, went to the house for lunch so the building was not occupied.

A safety report was issued baed on this accident which caused the contractor I worked for to inspect every air compressor at NASA Langley and Langley Air Force Base. We inspected every compressor from the large commercial ones the size of a two story building to the small portable compressors that were being used in shops and aircraft hangers.

[Chris Padilla]

If Keith Outten, our Admin, sees this he'll scare you with the work he used to do. Bottom line is that a rusting tank with pressurized gas in it can explode. Why take the risk if you know something is going on?

[Chris Padilla]

Ha!!! There ya go!! Too funny we posted only a minute apart.

[Martin Wasner]

It'll take an extremely long time to rust through, I wouldn't sweat it.

[Silas Smith]

My co-workers grandfather was killed when his tank ruptured and hit him. He was really close to his grandfather and it was really rough on him. I've been a little paranoid since about keeping my tank drained. If I hadn't been his co-worker at the time, I would have been sceptical of the story.

It shot up through the ceiling, bounced off the roof and came down on his grandfather, killing him instantly.

[Silas Smith]

How does one go about cheching a tank for safety?

[Steve Kinnaird]

How does one go about cheching a tank for safety?

Sounds like a job for ........
Myth Busters!

[Steve Kinnaird]

I don't know of a compressor that doesn't have a Pressure Release Valve.
I would believe that the pressure would have to blow that valve before rupturing a tank.

I think you would get a small crack first that would produce load a hiss and possibly a spray of water before a tank would just burst.

Inspect your air tanks, drain them periodically and keep them in good repair. Like any tool, it will do it's job, if you do yours.

[Michael W. Clark]

You could take it to a steel fabricator that does pressure vessel work and have it hydro tested.

I would be interested in any sources for a replacement tank. I have an older Curtis and would like to have a new larger tank.

[Dan Friedrichs]

I don't know of a compressor that doesn't have a Pressure Release Valve.

But that's likely set at higher than nominal tank pressure. If a tank usually hold 125PSI, the pop off valve is probably set well north of that. Won't prevent a structurally unsound tank from bursting.

I agree that it seems unlikely that a tank would spontaneously and catastrophically rupture, but there is a lot of energy stored in even a small tank at even a few dozen PSI. It has certainly happened.

[Dan Hintz]

I don't know of a compressor that doesn't have a Pressure Release Valve.
I would believe that the pressure would have to blow that valve before rupturing a tank.

A relief valve set to, say, 200psi, won't pop off if the rusted wall of your tank suddenly becomes a 150psi relief valve.

[Chris Damm]

I had one that developed a leak but while helping a buddy on a jobsite his compressor blew. It was far enough away from us so no one got hurt but we had a wall to repair. Why take a chance, new tanks are not that expensive!

[Keith Outten]

Most people don't have the equipment to inspect a pressure vessel.

The first inspection that needs to be done involves removing the paint from all of the welds where the compressor attaches to the tank. These welds can fail due to the constant vibration over the years. Once the welds are clean a dye-penetrant test is done to inspect for cracks. Its rare but some people remove the compressor from the tank when its new and mount it in a remote location.

To inspect the tank an ultrasonic thickness inspection is done which measures the tank wall thickness. This can be done without removing the paint.

You might be lucky enough to have a nondestructive testing lab in your area that can provide the service for you, if not then replacing the tank is the least expensive option. IF you drain your compressor tank regularly it should outlast the compressor, if not then you have a safety problem that is very dangerous.

We had a bottle field at NASA Langley explode years ago. Two rows of vertical bottles were about 70 feet long buried in the ground with 10,000 psi air on them and when a weld on a several ton manifold failed it took off like a rocket and landed about one block away in a parking lot. This happened just ten minutes after quitting time, had it happened earlier several people could have been killed and obviously several cars totally destroyed. I've seen my share of major accidents though the years when I was an inspector and for the record I had Level 2 certifications by the American Society of Nondestructive Testing in MT, RT, UT and PT along with a Level 3 Examiners certification in visual testing. I was also an American Welding Society certified welding inspector. I was certified for Structural Steel Inspection and high strength bolting. At NASA I worked on all of the high pressure systems and wind tunnels as the inspection coordinator for the recertification project which involved 10,000 psi air, methane, oxygen and a host of other nasty gasses and all of the 350 psi steam systems. I worked at three nuclear power plants, two fossil power plants, several submarines and a couple of aircraft carriers and I spent some time at a variety of industrial plants over the years, the most memorable was the Budweiser plant in Williamsburg

Don't take chances with any kind of pressure vessel and that includes the hot water heater in your home....check the relief valve regularly to make sure it works.
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