That air compressor explosion video recently commented on

[J Tiers]

I have a ex Navy air compressor air tank built in 1958, made with 9/16" thick steel, rated for 600psi and the inside is coated with some white sealant/paint/epoxy/whatever and is in perfect condition.

My assumption with that is that the coating was applied and also checked for pinholes carefully, by some means such as filling with conductive solution and checking resistance. Navy stuff, all MIL stuff, tends to be checked at many stages of production. Might have been coated twice to prevent such defects.

A made-in-china, or for that matter, a made-in-Ohio tank for a consumer application is not likely to get a double-checked or even double-coated treatment, just on grounds that it costs more, and nobody will pay for that when they can get "the same compressor" a lot cheaper without it..

There is also the point that a 5/8" thick tank is going to stretch a lot less than an under 1/8" thick tank for consumer use. Stretching of the tank , even if it does not get to the yield point, will have a tendency to crack coatings, making them basically useless as protection, and turning the coating into a "corrosion protector", as corrosion starts at a coating crack, and proceeds quickly through the tank thickness, just as if does on a truck fender, safely protected under the remains of the coating.

Sure, a special and more expensive flexible coating might be used, but....... we are talking consumer stuff here, where price is king, and if it looks the same, it IS the same (to the person who buys it).

[dian]

are tere any plastic tanks? aramid/carbon fibre maybe?

[old mart]

Ultra lightweight oxygen bottles have been used in aircraft. They are made of aluminium and are wound with kevlar, or carbon fibre. They cannot be hydrostatically tested and have a fixed life. Any damage to the surface which reaches the windings results in the bottle being scrapped. I always thought they were an expensive gimmick.

[Joel]

They are made of aluminium and are wound with kevlar, or carbon fibre. They cannot be hydrostatically tested and have a fixed life. Any damage to the surface which reaches the windings results in the bottle being scrapped. I always thought they were an expensive gimmick.

Composite cylinders are used very extensively in SCBA's (for firefighting). They get hydro testing every 5 years and they take a pretty good beating in firefighting use. These bottles are pressurized up to 5,500 pounds, with 4,500 being commonplace.

[Ringo]

composite bottles can take an enormous amount of abuse. I saw a couple of F-18s remains that had hit the water at mach .9999xxxx and the composite bottles was the best remaining parts you could recognize. even aluminum forgings/trunions were blown to smithereens. but the bottles looked like only paint scratched

[johansen]

1 liter soda bottles. Just need hot glue, and a bunch of 1/4" irrigation T's to connect them all together.

[larry_g]

One of the things I ran across working on a dewalt compressor, https://www.lowes.com/pd/DEWALT-4-5-...E&gclsrc=aw.ds , I found there was an expiration date sticker on the tank. Something to the effect of "Do not use after 2025" So the good quality cheap stuff is now having an expiration date.

lg
no neat sig line

[RMinMN]

Ultra lightweight oxygen bottles have been used in aircraft. They are made of aluminium and are wound with kevlar, or carbon fibre. They cannot be hydrostatically tested and have a fixed life. Any damage to the surface which reaches the windings results in the bottle being scrapped. I always thought they were an expensive gimmick.

Try carrying a steel air bottle around inside a building with the rest of your firefighting gear. Then try the wound aluminum tank. While quite expensive, they aren't a gimmick.

[Doozer]

They do sell stainless steel tanks.
You could make them on the thin side,
as then with stainless, corrosion would no
longer be an issue.

-Doozer

[reggie_obe]

They do sell stainless steel tanks.
You could make them on the thin side,
as then with stainless, corrosion would no
longer be an issue.

-Doozer

Who would pay extra for them? Not the guys who flock to the bargain 60gal. big box compressor with the fake 5hp motor
Industry doesn't have a problem with steel ASME coded steel tanks and regular inspections.

[Illinoyance]

Damn, I have the same model compressor. My drain valve is not readily accessible. I think I will put on the type of drain valve used on air brake tanks. It has a cable so it can be opened without crawling under the truck.

Weld metal will probably not match the exact chemistry of the tank material. In the presence of water that mismatch will cause galvanic corrosion. The tank and base metal are close on the electro-chemical series the galvanic corrosion will be slow. Having the longitudinal seam at the bottom is the worst place it could be because it will be exposed to condensate. My compressor is hiding behind my Taft Pierce surface grinder. It had to go through a lot of iron before it gets me.

[boslab]

We had BAs the early Sibe Gorman were bloody heavy, the new drager must have been composite, they were light, or lightish, air receivers aka tanks were annually checked, but usually by opening the manhole and climbing in, if they were rushed the hospital guy got his wallpaper paste out and did wall thickness with ultrasound, but they didn’t put off inspection more than a few days, wet air was always a problem, even with dryers, think aftercoolers weren’t that good
mark

[rickyb]

Finally got around to watching the video. Got a good laugh when he talked about coiling the inlet pipe to cool the In going compressed air. I guess he thinks the water should enter the tank in liquid form.

[Black Forest]

In Texas we coated the inside of big acid tanks with Tnemec which is cement spelled backwards. This was more to stop the acid from reacting with the metal than to stop rust. I would think that would be good to use inside an air tank.

[old mart]

Try carrying a steel air bottle around inside a building with the rest of your firefighting gear. Then try the wound aluminum tank. While quite expensive, they aren't a gimmick.

Those bottles were not the small portable ones., they were the 76cuft oxygen statics. The next ones were the lightweight ones which had a 25 year life from first test date. Then the thicker wall heavy type which did not have a set lifespan.