"HYD" refers to hydrostatic pressure testing. They fill the tank with water and pressurize it to 250 PSI. They use water so if the tank ruptures, there is no explosive release of pressure.

I had a good chat to the man who does the insurance inspection on our compressors at work... he used a thickness tester and a camera to check them out every year. The big one was made in the 60's . He said they will normally blow a pin hole in the tank when corrode badly and very rarely explode.. Only after people have tried to repair the tanks by welding up the pin holes and of patching in new steel and drain fittings do they generally become dangerous due to the heat from welding and the stresses caused by it..

Functionally operates just as it should kzfaq.infoUgkxiiMg_x4gIWeXMWfBnDdRnME4qJUAva4w holds pressure perfectly when not in use. Glad one of the other reviews pointed out that the bottom pressure release valve was open; thought it was defective at first.

I bought an old one, a Clark Tiger or something. It was £50. I probably spent about the same replacing valves and stuff. It vibrated so much when it was charging the tank it would roll across the floor. The wheels had fallen off so it achieved decent movement purely by vibration. I sold it for about 100, bought an electric nailer. Which has since broken. Now I use a hammer and nails.

This one would have probably lasted longer than your new one! Quality of these things now, is very poor. I bet your new tank was not that thick. Thanks for your video. It was very interesting.

Had you not got no cutting discs, hard work with the grinding disc you used to cut it open

Black coating you called protective coating is really just mill scale. It’s iron oxide that bonds to the surface of hot rolled steel. It protects if from atmospheric corrosion.

I purchased a 2nd hand air compressor that was in "good condition" from an auction. I was shocked to find that it was 1/3 full of water. You just never know how the last owner treated it. I was able to pull it to bits, clean and inspect the tank visually and hydrostatic pressure test it. I was happy to keep using it. However during transport the water with iron particles contaminated the high pressure line from the compressor pump and the non-return valve would get dirty and not seal. I was able to clean these lines and fix the problem. However had I known that original state of it, there is no way I would have purchased it.

Appreciate that you took the time to diagnose, film, and put it out to inform us. ** never weld a tank, they are heat treated after all welding is complete so the tank can "breath" like a lung with pressure changes.

I used a compressor and nail gun in a loft conversion once and forgot to turn it off after work. It started up at 2am and scared the shit out of the clients living there😂 don’t use it now after getting a Ryobi battery nailer

I rebuild air compressors here in the mountains of Colorado. My preferred method is to take all of the fittings out of a pressure tank, and look inside it. Light it up from inside with a very small bulb that will fit into any one of the half inch or 3/4 inch holes. Then drop an assortment of bolts and nuts inside it, with a solvent like lacquer thinner or just about any other type of a solvent fluid. Rattle it around as long as you can stand it until your arms get sore, and then dump everything out, pull the hardware out with a magnet. Then the tank will look much cleaner inside, if there was any rust. Colorado is west of the hundredth Meridian in the US, so it is very dry here. Relative humidity is very low compared to the eastern part of the US. So rust as you see, in the British Isles, is simply non-existent here in the West. Lucky for us. And then if I really want to get carried away I will pour paint inside it, the best rust resistant oil resistant paint that I can find, and slosh it around to make sure all of the bottom of the tank is completely covered. Let it dry, run some air into it and leave one of the holes open, so that the air can get out, to help it dry quickly. Assemble everything, and you have an essentially brand new air tank.

Interesting video . My compressor is 20 years old . Must admit when not in use . The drain is left open . The motor and pump on yours has still got life . Both could have potentially been refurbished and built onto a new tank . Cool video

I have been in the air compressor business since 1979 I wish people would realize that an air tank is actually stored energy! and it is so important to drain the tank regularly. and never buy a compressor that does not have a certification tag ( the welded 3x5 ") metal tag on the tank, this tank was a certified tank and still had great damage from neglect. good video. THE Compressor Guru

I don't see why compressor tanks don't have some kind of coating inside either aluminum or stainless. Or some kind of rubber to help extend the life.

Good video but I have never seen anyone try and cut metal with a grinding disc like that.

That corrosion on the top side of the tank obviously meant it was used in Australia at some point.

Its old machinery, of course it still works. No PCB board, no pre-installed failures... Solid item. Personally, I have always been terrified of air compressors, as well as flammable gases . Worst of all, flammable compressed gases (propane tanks, butane cans) and I have always wondered why these aren't made of stainless steel, or at least coated internally with a paint or protectant to prevent rust... I mean, the inside is never touched by solids, it wouldnt degrade at all presumably...

i have one of those mine was never checked and after i saw another one explode,,,, i wont be using it in the house again!

The one you have there is from an old range which has what we used to call a ‘T-pump’. That’s a pre-1990 machine and the pump will be mainly cast iron. Around ‘90-‘91 these gave way to a cheaper, lighter Italian-made (Fini) pump which was nowhere near as durable - especially the valve plate. A lot of the larger air receivers were made by Rednal Pneumatics in Shropshire and they were proper quality. The Rednal ones usually carried the name etc on the end. 50/60 litres was the transition between Rednal tanks and imported ones. If I remember right, petrol portables used Rednal tanks but electrics used imports - definitely lesser quality!!

I believe that is leaded steel; similar to that used in automobile fuel tanks - it is non-sparking. OSHA in the US had a case they thought a leaking o-ring or seal let too much compressor oil into the tank and the oil mist ignited when the compressor heated up in normal operation. So a fuel type explosion, not just rusty tank. 30 weight motor oil not particularly flammable unless it is in an aerosol

Just watched two vids on someone who's compressor exploded a week ago. The tank ripped apart like a bomb and the guy is lucky to be alive. Great vid and appreciate the advice and inspection tips.

Hyd means that the tank was hydro pressure tested with water. This is the correct and only safe way to pressure test a tank.

Nice tank 👍 Well designed and built. The welded seam is in great shape. This tank would likely fail via pinholes on the bottom centerline. Yes, horizontal tanks get a fair amount of rust on the top.

This definitely has me thinking about my compressor. It is at least 12 years old and has a broken wheel on it that I have been meaning to repair but maybe it isn’t even worth it. I didn’t even think that it would have a short life span.

Geez, I can't wait until technology advances to when we can shape titanium cheaply enough that we won't have to worry about air tanks corroding and exploding. ...then again, by that time, air tools would've been completely replaced by battery tools.

I've got a Kellog American Compressor, the date on the ASME certification tag says 1940, shell thickness is 13/64inch. I use it nearly every day and keep her filled to 140psi at all times! I certainly don't stand next to it and watch it fill up though. It's kept in a side compartment of my shed, so hopefully the chip board and drywall will keep the shrapnel contained, should it ever let loose.

A cut off wheel instead of a grinding disc cuts a LOT more efficiently

I used to use an old hot water heater for an air compressor tank.... Since then I’ve realized I’m not invincible.

I used to sell these (at Machine Mart) if you have a compressor ten years past the test date stamped on the tank, be careful, they should be tested. Or you can buy new tanks separately, these old pumps and motors are far more reliable than the new ones. We would scrap loads of compressors with burnt out motors or seized pumps (most only 2,3 years old) so speak nicely to the staff.

Andy, watched the video this morning and this afternoon when running up my 20 year old Axminster compressor a rusty pin hole blew out , no explosion just a lot of hissing, time for a new one I think

Hyd probably means hydraulic. It was probably filled with fluid, and pressurised in the same way as scuba tanks are.

All air receivers are prone to condensation inside, which causes rusting from the inside (which cannot be detected from the outside)... At the end of the day the water should be drained via a tap at the bottom, preferably with the cylinder still under pressure to blow out the water... It should then be left open until the compressor is next used. All cylinders should be visually checked on a regular basis (a cheap video camera can be used inside the tank), and pressure tested at least once every two years, using water (not air) and a boiler test pump to 2X (or better still 3X) the normal working pressure... Any weaknesses , or thin spots, will then show as water leaks - if you tried the same test using air the cylinder coud explode (as seen in another YT video, caught on security camera)... Compressed air has immense stored energy, whereas water is virtually impossible to compress. so doesn't store energy.. Having said that I have an old riveted cylinder, so at least pre WW2 - I know it has rusted through as it sits on a block of wood with a piece of rubber between - it blows off at about 50psi..... I've just bought a newer replacement, and will pressure test that before I use it.... The old cylinder will become a garden BBQ or fire-pit....

You get a lot of condensation inside any pressure vessel. The shorthand life of a pressure vessel is ten years, then inspection is required... Most of us get complacent enough with gas bottles, so unfortunately air bottles seem to get ignored until something goes wrong.

Hyd will be with water. It’s much safer to test with water a pressure as there is much less stored energy. If we are testing with air on site we have to set up exclusion zone and all sorts of things. If we test with a fluid we don’t have to.

All Compressors have a Safety Valve. The tanks are designed to take at least 600psi which is probably 3 x the pressure your engine/pump could deliver.

You could have made a small forge of the tank if you're into that sort of things. Pask Makes did a forge pig to heat treat steel to make his own tools etc. The motor is also still usable to make other machinery.

Years of life left in that

Hydraulic testing, fill with water and pressurize and see if it holds for a specific period of time.

I recently heard about a guy’s compressor exploding & nearly destroying everything within 6 ft of it. I was not aware this was even a problem, but clearly, it is. This begs the question as to why compressor manufacturers don’t heavily treat the inside of these tanks or use a liner of some sort? Have there not been any liability lawsuits from people injured or damage to property? One would think there would be a standard of time or use to go by…

I would have thought an explosion most unlikely, one of those pits would get so weak it would just give way and you'd hear a nice hissing. Also why would it crack, unless you'd damaged the outside severely somehow, since it has been clearly ok for 37 years? Elf and safety gone mad sir!

I worked for a company that used air compressors to operate gas/air pumps, and the compressors had to be serviced regularly ie change pressure valves,air filters etc and replaced every ten years.So you got good service from your old one, but definitely time for a new one.

"The prime directive - we do not fuck with pressure vessels."

Great video. Pretty scary when you think about it. I’m not sure I even trust brand new tanks considering the quality of manufacture on everything nowadays. I’m going to make sure mine is far enough away from me in a worst case scenario.

I have a similar one from 1962! I have been watching some tube videos and have decided not to use it anymore though it still works fine. I have drained the tank often but very dry here,not much humidity just the water created from compressing the air. I think I will cut mine open as well.

I did have a tank rust out on me and it didn't explode. It was the small 10/15L type and was about 15 years old. What actually happened was.. as you show.. a ribbon of rust pits or holes along the bottom inside of the cylinder and evenually one breaks through so you get a small whistle and obviously it doesn't hold the full pressure any more.. The first hole is probably only a pin hole but does make you aware... so you explore and quickly find the offending area.. You think about repairs.. bit of welding (can't do that..) an epoxy patch.. (nah..) screw a plate of metal over the area.. (probably the best option.. ) Have a cuppa tea.. think.. Snip off any extraneous useful looking bits and kick it to the curb.. Hello Machine mart.. whatchgotonoffer..?

Wow, for 37 yrs that is fantastic.Doesn't owe anything

Thanks for the clarification that the fire extinguisher being tested was filled with water. But I think the tank the fire extinguisher was submerged in was open to the air and therefore not pressurized.

Next time Hydo test, read the inspection label on tank for max psi. Fill tank full of water, install 2x psi gauge, hook pressure wash wand to tank and pressuruze tank to 2x rating.

Loved that intro video of you moving the compressor... was something a little different but keeping with the theme of your channel.

That was interesting, I own a stand up compressor, I keep the drain valve open at all times. I was wondering if the stand up type would be better because the condensation would drain out better.

lol, love it, that is heavier than I remember it being, that is getting old my friend, I know exactly how ot feels

That was very interesting, I asked a question on this very topic on KZfaq as I have a compressor, probably similar age to yours, but I haven't used it for a few years due to these very concerns. I think in view of what you have demonstrated I will retire my compressor also. I suppose the worst thing that could have happened to you would be to cut it open and find it all nice and clean and shiny!!!

Fascinating Andy. Been around them for years often wondered what the inside was like. Had a good at the intro and the sombre music during the strip down. Bang on.

I think i depends on how will you take care of it. If you put a water separator / dryer in right after the pump. It could last for a very long time. That is what I am planing on doing when I get my big compressor.

was he cutting into that with a grinding disk?

For anybody interested, the formula used to calculate the hoop stress in a cylinder, (the most heavily stressed part being the parallel sided portion) is PD/2T, i.e. internal pressure x diameter divided by twice the wall thickness. With deep drawn cylinders the burst failure is normally a straight line down the longitudinal axis; with welded (rusty) tanks it can be more chaotic but it is surprising what decent steel can withstand. Even the humble 15mm copper pipe can theoretically withstand more than 20 bar of internal pressure, though I don't think I'd like to cycle it too often!!

That guy is clueless on how to lift a heavy object to the bench. I was waiting for the OWWWWWW as his back threw a disk!

Excellent video, thanks.

Great video, very informative! If that's used at home, there's no regulation (other than the usual CE Marking for supply) that mandates any regular inspection. But if it's used in a workplace, and the volume x pressure is more than 250 Bar Litres (excluding the 24 Litre, 10 Bar "Hobby Compressors"), it would legally need a WSE (Written Scheme of Examination) under PSSR (Pressure Systems Safety Regulation):2000, which would dictate (certified by a "competent person", based on a risk assessment) what degree of inspection (typically ultrasonic thickness test for the receiver and a pressure test of the PRV and Gauges against a calibrated gauge). The receivers ("pressure vessels") are always supplied against a design code (should be stated on teh data plate!) which specifies the minimum design thickness, plus a corrosion allowance (EN 286-1 is typically 2mm + 0.5mm for steel, but older codes had a greater thickness). That one was probably the older BS 5169, possibly with 3mm + 0.75mm corrosion allowance. Life expectancy will depend on how often the condensate is drained from the receiver and often it's the compressor (especially if not regularly maintained) that limits the life... Modern industrial compressors tend to be coupled with an automatic timed or zero-loss drain, so you don't have to remember to do it manually.

Seeing a pressure vessel tag welded to the tank is a higher quality tank also bung plugs welded to the tank

The tank had another 40 years of life left. Old style with a 4.0 safety factor and back welded long seam. No problems. New tanks are built to 3.5 safety factor.

the top is where water drops settle when water accumulates inside

That tank could be a great diy barbecue/grill :D

I would have removed the end plug and used a lighted scope to check the interior .

Funny.... the sad music while dismantling the compressor. Then the head banger music while cutting the tank open. This is probably a VERY good idea to get rid of this old girl!

The condition of this tank is really not that bad given its age. The thing to have done would be to have it hydraulically tested "HYD" is hydraulically tested to 225psi. I am lucky that I have a pressure vessel tester at the bottom of my road. I may be wrong, but I believe a pressure vessel such as this should be re-tested after it reaches 10 years of age... but it does depend on the size of the vessel and what use/working pressure it is being put to.

You could have used this as a secondary air tank for your new compressor Andy, You get more air flow then, just fill a check valve, look up on YT about it

hyd probably stands for hydro, usual way of testing pressure vesels - it gets filled with water not air, that way if vesel fails it is much less dangerous

Interesting to see the condition of the inside of the tank. In the future you could remove the fixtures, hook up a pressure gauge, fill it with water then hook up a pressure washer to hydro test it yourself. Also you can get a boroscope camera that hooks up to your phone for less than $20.

I have a soviet compressor, an old man used it für 40 yrs and i borrowed it für one day and end of the day the tank started to leake air at the welds, turned out its lifespan was exacly 40 yrs.

I doubt they make them anywhere near that wall thickness anymore.

Workshop wood heater would be the way to go, mate👍 Seen a video where an oldie let go with a hell of a bang, caught on CCTV, Grandson, luckily was home at the time, severely sliced through both granddad's legs...😨

The HD stamp is hydro test , in order for any tank to be allowed as a compressor it has to be tested using water or glycol . that was my job when I worked on oil seperators, we would have to fill the tank from the bottom (if done from the top you will have air and will not be able to test) we had to test 1 1/2 times the working pressure which is where the 225 stamp comes in. It's a max psi of 150 so 150 +75 =225 . it has to hold that pressure for 15 min. And all welds are checked for any leak. By law anything over 110 psi has to be filled with liquid so that if there is a stress crack , or a faulty weld you take a quick shower otherwise goid chance your not going to be around for any other test as it will explode like a grenade shooting metal into whoever is near the tank. If a tank gets to thin from water, rust you can cut a section out and basically put a new piece in a band aid . the second serial no. Is logged into a federal data base which is a paper trailall the numbers on that tag will tell you where that steel waa milled and when , who welded on that tank , who pressure tested that tank and who did the final inspection giving that tank a pass to become a compressor. So all them tags and numbers are it's birth certificate if you will.

In a commercial setting, you should have an inspection done on a regular basis for your insurance where the tank is tested. Industrial machines should also have a autodrain on the tank (should be called a receiver) which limits water build up and increase the life expectancy

Thanks for this video! 👌🏽

Hyd. stands for hydraulic. As other comments have said, liquid (hydraulic) testing is much safer than gas (air) testing 'cos if it fails it won't explode - but you might get wet!

Using a grinding disc instead of a cutoff disc?

The correct way to do this would have been to perform a 'house' hydraulic test first, then open it up and see how the steel was, thus establishing at least some correlation. As it is we have no actual information, though given the 2.4mm residual thickness I agree with a prior commenter, it would probably last about as much at is already has at least.

you should have a hoist mechanism in your workshop for your safety.. Good content video Sir.

Very interesting Andy, that’s what put me off buying a 2nd hand one. I’m sure most would be fine but the peace of mind from a new one is almost priceless. Could that be a video or podcast idea for you. To buy new or used?

Could do without the bad and loud music. A well made and thick metal tank. Twice as thick as most at 1/16", 1.66mm. Drain did not protrude inside preventing total drainage of water. Wise move to discard it. You would never see cracks until after the explosion. They can be deadly. Hyd. means Hydrostatic Test Pressure, 1.5 times Operating pressure. Tank is filled with water THEN pressurized. If it does burst, there is no catastrophic damage as water is not compressible. With that large hole at one end, it could have been coated inside after manufacture. Todays tanks are much thinner and made of Chinesium.

I need to get a bore scope so can look inside mine. It's a 60 gallon Coleman I bought new in 2000 at CostCo. It only gets occasional use, but I live in a very wet and cold climate. It'll be interesting to see inside.

Just before you start cutting is where you hope it was actually dead... extremely interesting to see just what happens in there and how well the airmaster compressors were made. But I am now thinking about the old one I just replaced and thinking I should recycle it.

When I score a compressor with a questionable tank I slice off the mounting deck using a 6" thin kerf cutoff wheel. I also slice off the wheel mounts with the wheels if they are any good. Then if the tank seems worthy I slice the tank horizontally and use the halves for other purposes. Large tanks sell or barter easily to people welding pig cookers so nothing is wasted. What few remember is the motor/pump deck is mounted to the tank for convenience and some compressors came with NO tank from the factory (I've an old military example which works well). You can and I do run compressors separate from tanks and that makes large units easy to move. Thanks to cheap consumer junk integral pump/motor units I regularly find good tanks (I use a USB borescope with my shop computer so I've a large display) to use with frequently superior old pumps. I crack all my drain valves on installation since I don't need to store air between uses. I've no condensation buildup that's not promptly blown out at first start. Discarded systems rarely failed as a system. This goes for computers, compressors, cars, trucks, and much more. I dont prettify anything I repair or rearrange, I do ensure it's safe to use. Note that just a nice coat of paint does NOT restore machinery. Overhauls do because the innards are what functionally matters. Want a ten horse and can't afford the wiring etc? Two fives are a common commercial solution and I only run a single when not blasting.

What is the make/model of the new compressor you bought - any recommendations?

That made it a long time!! I had a compressor that was built in 1975. I scrapped it but kept the motor and pump. They bring good money!!

About 24 years ago, we replaced the 100 gallon tank in our 30 year old shop compressor with a 125 gallon stainless steel tank. We bought the tank from a scrap yard for $50. Now we don't have to worry about it exploding anymore. It is still in use today.

I have and use a 50+ year old 60 gallon 2-stage. I've had fittings fail, but never an issue with the tank or welded bungs.

"not taking the risk"... Just get an hydrostatic test pump and test the tank at its test pressure, or have someone test it for you. No need to throw away a good compressor.

At work I took over responsibility for an at least ten year old clark whisssper all in one compressor. I could hear water sloshing about inside the tank. I removed the drain tap and strangely no air or water came out. on further investigation I found that although the drain threaded boss had been welded to the tank the tank had not been drilled by the manufacturer. I returned the unit to Clarks R & D dept. it came back a few weeks later with a hole drilled through the drain boss so the drain tap worked. strangely enough it failed completely a few weeks later. I wondered how many of that batch hadn't had the drain hole drilled through at manufacture.

I tought that you used thick grinding wheel on purpose instead 1mm cuting one :-)

Now to cut open a brand new ALDI compressor and see what's better!

I think that small pressure tanks are supposed to be replaced after ten years from test date,in industrial and commercial use they have to inspected on a regular basis by a competent person like once a year, insurance companies will usually arrange this.

Interesting choice of music at first; as if you are putting a beloved pet down.

"Hid. Testing is Hydrostatic test. That means that they filled the tank with water and then with a hand pump took it to 2 X the nominal pressure. In your case it was less than 2 X but that is the legislation of each country.

No Andy... it isn't heavier... we're _older_ now :^) Even draining regularly I won't keep compressors around forever. Just not worth the risk over time. EDIT: Can't find it now, but looking at compressors recently I recall one of them said to replace after 5 years of service. They have expiry dates on the tags now like gas cylinders.

Geezuz mate, you really made cutting that lower section out look like a monumental task !!!. You really need to get yourself a packet of metal cutting discs NOT grinding discs. It would've taken 1/20th of the time to do the same task. Then again, I'm just a Mullet headed Aussie from down-under who is a lazy prick and I do things as efficiently and time saving as possible. lol

Pro-tip. Never put any kind of liner in your tank. Yes, liners do HELP prevent rust and such, but with air compressors, you want your first failure to be a pinhole from corrosion. Then you throw it out. If you put in a liner or any kind of sealer, you will plug up corrosion pinholes, but that means that instead of a pinhole being the point of failure on your tank, it will instead be more likely to be a large failure at a seam that does it in... which means instead of hearing "tsss" and knowing it's time to replace it, you will hear nothing until it explodes.

I found your video most interesting as I have exactly the same compressor which I purchased from Machine Mart in 1983 - it has the same datte of test etc. It has served me well and continues to do so never missing a beat they were made in Italy as was my MIG welder. Everything seems to be made in China now.

the tank was tested to like twice it's operating pressure, so it should be fine with like half the metal gone even.