When I was an engineer working for a major oil company we used to hydrotest pressure vessels by filling them with hydraulic fluid or light oils (diesel fuel) and compress them up with a hand-pump (similar to what you see with a small hydraulic jack). We factored in the compressibility of fluids, temperature and something known as "the steel factor". Steel does stretch under pressure and it adds a fraction of a percent to the capacity of the pressure vessel and in a failure, that steel stretch will cause an outpouring (jet, spray, stream, etc..) at the point of failure. On some of the things we tested we operated at up to 2250 PSI (on 0.375 wall thickness steel) where things were connected with ANSI 600 flanges. The pressure had to hold for twelve hours and we had to record pressure to the fraction of a PSI and temperature of the vessel. On some of these systems it was for a 30 mile long segment of pipeline that had blind flanges added at the ends (or double block-and-bleed valves). We had one notable failure on a 12" diameter pipeline that ruptured at a point where it was four feet underground. It blew a crater in the ground that looked like an artillery shell had gone off. The pressure at the end (where we were) dropped off very quickly but there still was enough dynamic energy in the system because of the steel-factor stretch.
Keith, long time lurker of your channel, here. I inherited a vintage Sears Craftsman air compressor and have been wanting to do some kind of hydro test on it just for, as another connector said, peace of mind. I didn't want to purchase any equipment that i would probably only use one, or pay to have a fully-certified test done, but as yet-another connector says, Ice seen the aftermath of a small shop compressor blow-out due to a rusty tank and I'd just feel safer with literally ANY test. I had no idea i could potentially use my little pressure washer as a pump, it never occurred to me, so thank you for that! I likely won't push the old thing over 150, I'll probably never use it for more than 80-100psi but i have over 4 decades of find memories for it and i want it to run again.
When they hydro test high pressure gas cylinders they get pumped up with water to the test pressure but at the same time they measure the expansion of the tank under the test pressure. The test I watched was done by placing the test tank inside another unpressurized tank filled with water. As the test cylinder expanded it displaced some of the water in the outer tank. The displaced volume was recorded by reading a site glass affixed to the top cover of the testing tank. They were looking to see that when the when the pressure was released, the cylinder returned to its original volume (shape). and there was no peppermint deformation to that tank being tested. If the sight glass didn't return to the same starting point that indicated the tank had exceeded the elastic limits and had failed the test even though it didn't leak. Continual cycling such a thank would cause it to eventually fail.
Craig that is done on high pressure tanks like oxygen, nitrogen, dive tanks etc. When I was working at a company that used a lot of tanks I often saw tanks delivered that were manufactured in WWII and a few as far back as WWI. They had many cycles and been pressure tested many times. Although there was a series of dive tanks that were known to fail near the neck.
Yup, that was because they used the wrong aluminum alloy (6351-T6) in manufacturing. The neck would develop micro cracks and then fail. We had a lot of them in the fire service as well. Did a lot of hydro testing of SCBA tanks over the years. Those are tested using an eddy current test, visual inspection and then hydro tested if they pass those two first. We just took them out of service, cut them up and scrapped them. Not really something you want strapped on your back if it fails... Have seen the results of that, not a good thing to see...
I'm glad I watched this before putting a used air compressor back into service! I've seen air tanks fail before with compressed air and one took off like a rocket and banged into the shop ceiling, doing lots of damage - and could have killed someone if they were standing nearby! Great job - I would never have thought of using a pressure washer to test it.
Well Sunny beaches! I had a 80 gal tank that rusted through so I found one for 200.00 now when I was not to sure of the tank and wanted to test it. I read about people suggesting water test it, when I did not know who would do it I saw my pressure washer sitting there. After about fifteen minutes I found a quick air connector and put it on the pressure washer. iI figured maybe leave about a cubit foot of air in it and fill it with water, then I thought let’s see what RUclips says about it. Wow found this video! Doing the same thing! God is Good!
i do a lot of hydro pressure testing here in the UK on check valves for the gas and oil industry when doing a test like this with large volumes of water please still take care because if you do have a failure of the tank or any of your fitting you will be surprised at the results as you can see when Keith let the pressure out at the Bottom of the tank if that had being a fitting coming off you would know about it i do pressures from 350 psi up to 15000 psi on Hydro so have plenty of experience with this type of testing it is safe but you still need to take care ENGAGE SAFETY SQUINTS and i would have put my self behind something when doing this test please do not think i am having a go at Keith but unless you witnessed a test go wrong or had one your self go wrong like i have last year when a gasket let go at 4.500 psi you then have a lot more respect for any type of pressure testing (yes i know it was only 250 psi ) but it will still hurt so take care
@@bottomlands I have found through my journeys in life people who care about punctuation and lord it over people lack practical knowledge of the world and cannot actually do what they are critiquing. Iff you use punctuation to prove you superiority you are infact inferior and most likely insecure. That being said. I helped my uncle jack off a horse. I helped my uncle jack, off a horse. Witch one is correct? 🤔
@@bottomlands have you ever written a hydro test procedure for a 25 mile DOT pipeline or actually tested and inspected a hydro test? I have for the last 15 years. Have you ever over seen a 1.8 million dollar project? I am right now. Do you have an IQ of 145 ? I do. My point is dont dennagrat some one over punctuation English may not be his first language. When people try to run a person down over small stuff they don't get the big picture.
Very well explained . Being a boiler plant engineer safety and annual testing is paramount . Few non pros would perform a wall thickness deterioration test on an air receiver ( a good idea after 10 years ) but ya could remove the large bung plug ( most have one ) and do a visual with a borescope or drain camera .
@@calvingreene90 True, but this wasn't a purely hydraulic test. The air cussion at the top was enough to be violent in case of a rupture. See how the water shot out at the end... Still a lot better than a pure air test.
@@jackmclane1826 There was the little air bubble but it was mostly the steel's elasticity. The plastic deformation from rupturing would have been slightly more than a pure hydraulic test but not enough to ruin it for making a smoker. My Jr high school shop teacher had an air tank that had ruptured when filled with air hanging on the wall. I don't underestimate the power of compressed air.
Dude hell yeah! There's nothing like old man knowledge. I just bought an old air compressor but that tank hadn't been drained of water so now I'm scared to pump it up. Now I can test it without spending an arm and a leg at some shop!
Having done countless hydro tests of piping systems I want to add a couple of points. First, respect pressure. All things equal it is true that the dangers of air testing far outweigh hydrotesting but dangers exist any time anything is under pressure. Second, the leak at the gauge is a great visual. Most hydrotests fail because the test apparatus leaks.
No doubt! I was working on a wetland restoration project 12 years ago and a hose about 2-3 times the diameter of a fire hose that supplied water to a hopper used for making slurry blew. up right in front of me… and I didn’t even touch it! Needless to say, it threw me on my ass at least 10’ away from where I was standing! Yeah! Definitely respect pressure!
I enjoyed your video immensely, and have a compressor tank of my own, purchased second hand, that requires testing. Thank you.For all the 13 year old 'experts' and 'keyboard kommandos' out there here is the procedure used in the fire service, their LIVES depend on compressed air tanks."Requirements For Hydrostatic Tank Testing:1. Hydrostatic tank testing must be completed by a licensed certified tank tester with special equipment designed for the task. 2. The tank should be tested every five years. 3. The tank must be tested more often than every five years if there are any visual signs of degradation or damage. 4. Requirements under the law state that the tank to be tested must be filled with water and pressurized to 167% of the maximum operating pressure listed on the side of the tank. 5. The tank, including all of the valves and other closures, must hold the pressure test for at least 30 minutes without leaking or bulging. 6. Details and requirements for hydrostatic testing are covered under OSHA regulations section 180.407."
I had the horrible experience of being a pall bearar at a coworker's funeral. He was killed during a hydro test of a piping system. A hose broke and he was struck by water from the hose. There was a pocket of air in the pipe which added to the thrust of the water coming from the pipe. Lessons learned included included; hard piping all connections, making sure all pipes and vessels were filled 100%, using equipment intended and used exclusively for pressure testing, and keeping unauthorized personnel away from test connections. Good safety practices are required both at work and at home. Whether it be welding, cutting way wipers with a small bandsaw, pressure testing a compressed air receiver, or any other shop activity safe practices need to be followed. Bob
Keith - Thanks for making this episode. I looked at my compressor which sits in a corner of the basement with air lines to my nearby work bench and the garage. Couldn't recall the last time I drained water from the tank. Even forgot I had installed a radiator petcock in the drain! So it's been a while. The water that drained out was pretty clear and less than a quart BUT that compressor was manufactured in 1970! The 2 cylinder cast iron compressor is getting pretty tired. I replaced some reeds about 5 years ago. But it's struggling again so I'm retiring the old girl. Picked up a smaller unit at (sorry!) Harbor Freight - 8 gallon vs. 20 on the old Sears BEST unit. I noticed that every compressor in the store recommends draining the tank every day after use.
When I pressure tested my old Quincy 50 gallon tank a few years back I just filled it to the top with water and put a liquid pressure gauge on it.... I then made sure all the air was out and I capped it and left it in the sun. The heat soaked tank slowly built pressure enough to successfully test it. Works great as long as you have a sunny day.
thank you for the idea of using the pressure washer, I am in the middle of testing a intake manifold on a boat engine that had coolant in the oil I traced it to the intake, so before adding the oil and coolant I want to test it, thanks again
At Ball Aerospace, outside of Boulder Colorado, they had a facility that tested tanks. They were doing a repeat pressurization test, putting the tank in question through multiple cycles of pressure, and failed to realize that some of the water escaped with each venting of the tank. When the tank failed after several days of testing, the top half went through the roof and about 200 feet in the air.
Great way to have peace of mind that the pressure tanks is alright to use. I watched a video yesterday where a mechanic showed the aftermath from a compressed air tank failure. The shop was in disarray, with holes on the wall, & door, as well as all windows busted!
Keith i appreciate your video! i have an old sears air compressor from the 70's unfortunately there is a chunk out of the crank keyway and when i contacted campbell hausfield (who made the pump for the compressor) they wanted to sell me a new pump! After that they wanted to remind me of the safety of an old tank. Now i can hydro test mine mine though i pulled the inspection plugs and looked in the tank!
Informative video; I've had refrigerant recovery tanks "hydro-tested" for recertification, never really liked the idea of introducing water into a refrigerant tank. Now I understand the thought process of using water (safety factor) instead of another medium. Water & refrigerants shouldn't be exposed to each other, causes all sorts of problems inside a refrigeration circuit. I guess I have to trust whomever is hydrotesting the tanks properly dries the interior completely before shipping it back to me. I believe a deep vacuum pump (6 CFM or greater) drawn down to less than 100 Microns vacuum is an additional "no worries" about water inside the vessel. Good video, liked the presentation!
Thank you for clarifying that age-old incorrect statement that "water is not compressible". While it certainly has MUCH, MUCH lower compressibility than "air", it absolutely is compressible... and making a working test fixture that does so (to over 27 bar) has been a serious learning experience in physics.
The small air pocket at the top is actually useful, as that small amount of compressibility, allows the pressure to ramp-up slower. If the tank was completely full and you hit it with 3000psi, then the internal pressure would have risen very fast and it would be difficult for you to set the gauge to 225psi. :)
I can confirm that. I had (virtually) no air pocket in my tank and the pressure meter immediately went off the chart. I mean: way faster than in this video. I'm glad I had read this warning (and the one in the video)
Many, many years ago a friend of my fathers walked into his body shop to find the pump and motor from his compressor setting on the floor by a large hole in the wall. Most of the tank was found in a corn field about 1/4 mile away. All of the tank peaces were never found.
Thank you Keith! I'm looking to buy an older 360 gallon horizonal tank, and this is a great start. If it has the larger bung I'll have pros look at it, but never in my life would I have thought to use my pressure washer in this manner. I thank you for your video!
Hey Keith, Thanks for making this video. I was watching The Compressor Guru and he mentioned how you do a Hydro test. I posted this question on his channel and I would like to get your opinion. I would like to ask a question, what is the importance of draining the tank every day? I understand water and metal don’t get along with each other, but as soon as you turn these things on condensation starts to build up and pools at the bottom. So even if you drain it every day you’re not going to get 100% of the water out and it’s always gonna be damp inside which is going to promote rust. Thanks! God bless!! Blue
Hi. My late Dad worked for the pumps and compressors division of a globally well known firm. He had some stories about what happens if the valve breaks off a high pressure air cylinder. The air blast from a 3,000 psi one can cut a man in half. If the tank breaks free you have a high power rocket with a mind of its own. Even at one twentyth of that pressure an air or gas cylinder air filled explosion is potentially lethal. That's why there's a 150% oveload water test. In fact, the cylinder expansion should also really be measured occasionaly as over time repeated filling and emptying will lead to fatigue failure. This is a madatory requirement for things like diver's air cylinders. Drain the tank of condensed water vapour regularly, you REALLY do not want it rusting from inside out. It's instructive to multiply the tank pressure by the inside surface area to find out the forces involved. They may suprise you. Incidentally Keith is mentioning 'pounds' a lot when he really means 'pounds per square inch'. But, it's very good of him to raise this subject. It's important. BobUK. (edit to correct my spelling).
You are speaking of the principle that air bags use to lift heavy objects and pneumatic cylinders use simple low air pressure to operate valves over a large surface area. It is all in how one contains the pressure for work or to service that work. BTW, the just the sound a tank exploding makes from weakening due to rust will definitely get your attention.
Yes, know of a case where the oxygen cylinder in a welding set fell off and broke off the valve. Went through 3 floors of a concrete building, and also through one unfortunate standing on the one spot.
Nice easy test setup there Kieth! I imagine it would have done the full amount but it is an old tank and a test like that might cause a future failure. The thought of a tank like that exploding is pretty scary. Thanks I enjoyed the video. I'm restoring a ProAir 80 Gallon 6.5 HP 175 PSI now. It was not locked up but had some build up in the 2nd stage cylinder bore that would stop the piston a 1/2 inch from the top and not letting the piston make its full revolution. I've replaced the tank check valve, cleaned the bore to where it turns freely, replaced one capacitor and ran it with an open valve for ten minutes yesterday. I was going to do the same thing today and it popped the run cap on startup. That was a 2005 cap so I've got one ordered for it along with the oil filler breather cap. We used it for years at our Pipe Construction garage. An old tank is always sort of scary though. It is in very good shape though so I'm not to worried about the tank.
Thanks Keith. Very thoughtful presentation. When you brought that old compressor home I was hoping you would test the tank. Most people would have just let it rip and hope for the best.
Valve Monky covers the essentials below Keith, it is his specialist subject, and mine. If you were doing it again; Tilt the tank till the vent is at the high spot, trapped air is your enemy. Put a positive shut off valve in circuit to hold the pressure in. Working pressure only when retesting an old unit, 200psig would be fine. Remember to test and re-calibrate the relief valve - this is actually more important than hydro testing the receiver. ... and before you test it - ding it with a hammer, and if it goes 'clunk' rather than 'clang', just scrap it.
Because he was using a pressure washer, a *small amount* of trapped air is extremely necessary. It's a compressible buffer that allows you to add pressure in a somewhat controlled manner in the absence of a pressure regulator valve. Notice how the pressure rose very quickly and he over-shot his target. With no air buffer it could have spiked to the full output almost immediately.
It is quite exciting hearing the pops, snaps and other sounds, doing a burst-test on a test-specimen. I have done that :) We pumped up the specimens to 135 bar, before they leaked, no explosion at all with water. Just a pissing little leak of clean water. Of cource, just a little little bit of air was trapped during the test. Good for 25 bar, the design that is. The test specimen destroyed. Non-destructive testing is performed at 1,33 x MAWP (Maximum Allowable Working Pressure) as I recall it, cold or @ 20°C, save for higher temperature curves according to the material properties in question.
I did this about 50 years ago, before homeowners had pressure washers, by filling the tank almost completely with water and then using the air compressor to pump it up to 200 psi. I doubt that I had more than a cupful of space with compressed air. No problem.
That's exactly what I thought as well - I can just image the inside condition of the bottom of the tank especially if the original owner didn't drain the water regularly. It's going to be a rust bucket. Using a borescope is almost the very first test on any pressure vessel.
The good thing about vertical tanks, is that moisture collects at the domed bottom of the tank, unlike a horizontal tank. I had a 50 or so gallon Sears Craftsman air compressor with the horizontal tank marked as being built in 1949. I had no history of the unit when purchased. I owned it for better than 25 years before it developed a pin hole leak at a welded seam. The old Craftsman compressor was retired to become a BBQ smoker, and I purchased a 80 gallon, 5hp Ingersoll Rand vertical tank model.
It passed the pressure test. Not enough corrosion to worry about. And if Keith drains the condensate from the tank on a monthly basis, no worries in the future.
If there was significant corrosion it would have showed up when the receiver was drained. Not a definitive test to be sure but if it passes the squeeze then it's good.
Nice explanation! The comments are interesting as well. Also, I was thinking if the remaining air in the tank mattered, possibly tilting the tank so that bung where you put the gauge was at the highest point while filling with the water to push the remaining air out. If it even matters. Thank you and May God Bless.
Wow, Thanks, That was a great idea and I have learned a nice and safer trick. Wish this grandfather had done this test first, You can search Air Tank exploding on youtube and the explosion was caught on CCTV, The gentleman survived but was in the hospital for 2 months, Thanks again for the idea. The water would just scare the crap out of you but the air test would cut the crap out of you if it failed.
Because water is non-compressible it builds pressure much faster than air for anyone wondering how it built pressure so quickly. For air to build the same pressure you would need to pump in many cubic feet of air, with water it only holds what it holds so you are simply trying to force in more than it will hold and it instantly builds pressure because no more water can fit inside so the pressure is from the cylinder or tank slightly expanding, in this case there is a small amount of air at the top which is compressing too.
When testing any pressure vessel in your yard OSHA requires you to utter the phrase “ here, hold my beer and video tape this “ to your buddy. If a buddy is not available then a nervous girlfriend ( a proper wife would never help you with this ) or your home security system will do and make sure your recording devices are not password protected so the internet can enjoy the results. For those with a pressure washer in their butt , this was a joke.
One way to do this is just pump it up to max capacity with air, then set it vertically on a big pile of dry wood and then light the wood on fire. And then very quickly drive about a half mile away and try and catch it when it drops back in from orbit. I call this the maximum apogee tolerance test.
Good thinking to do hydro testing . I did considerable amount of air-testing to failure and few can imagine the destructive ability of even a medium size vessel when the failure occurs even at rather low air pressures . It is hard to over-engineer the confinement chambers necessary to contain the "shrapnel" as the result of the ultimate failure . Most of the time even the confinement chambers are partially destroyed . Air-testing is indeed life threatening !
I find these lower than tag rated home tests amusing. I've done many tank tests with old odd scrap yard or auction air, propane and other tanks I have picked up over the years and repurposed or added ports to or modified in some way and I have always done my test to 2x rated for a at minimal 10 minute hold and even done a few to 3x and 4x to push dents out. Never had one catastrophically fail either (I do stand around a corner and pressure them up remotely though) even with very rough looking air and propane tanks with build dates going way back into the 1940's!
The pressure washers I've used had a pressure gauge and pressure adjust valve. I'm a fan of cranking the valve down to zero and then back up to about the limit value I want before doing something like this, rather than bumping the wand valve on something set to 3000psi.
well i did not think that my comment would turn in to such a bun fight. just got in from work don't know what's more dangerous high pressure testing or making a comment on You tube ! .
crazy huh? youtube brings out the best of em. gotta keep in mind some of us like Keith didn't have internet nor much of instruction manuals, nor could a lot of read well, but somehow with all the crazy stuff we did, we made and by the way, things in the past were built a lot better. like my dad he had a second sense about building everything with maximum overkill. everything worked and lasted longer than he did. today with all the warnings based on harbor freight junk as the leader in tools for these poor kids to place their trust in, makes me wonder, so that is what their standards are built on. to them it's the deal, i mean it smells like tools when you walk in, but that's as close as it gets. i used to think those flash lights that harbor gave away was ok, but they're trash too.
I tried to get a new tank for my 80 gal compressor. The total cost, including shipping, was about the same as a complete brand new Ingersoll-Rand 480 lb compressor. Good luck with that old tank.
I was replacing a jammed safety relief valve on a hot water tank once. I stupidly did not release the water pressure on the unit and the damn fitting shot across the room with quite some force the moment I was done unscrewing it. It was just residential, so probably not more than 30 psi on it. I've also cut into plenty of water supply pipes while forgetting to depressurize... (seeing a pattern, eh?) When it's just water shooting at you it's just fun and giggle, like Keith says. The thing you want to be careful of is any fittings or similar coming loose for whatever reason during your test. Those could easily knock out teeth.
When I was with the Genesee County Parks & Recreation Commission we used a weed sprayer to hydro test air tanks. We would adjust the pressure regulator for the pressure we wanted.
Well done Keith. Some important points. Never screw in a gauge by the gauge body. Always use a wrench or you will damage the gauge. After filling the tank, always let the temperature stabilize. Preferably stand behind a wall when pressurizing. That dog didn't get old by being dumb! The leg of my small 3 gal tank is stamped with a "Destroy By" date. Sadly the cheap drains are a coupling welded in that protrudes Inside the tank, and does not allow complete drainage of any condensate. Never buy one at a Garage Sale! I have done countless Hydro tests and once witnessed a pipe coupling failure and 3,500 psi. Impressive. Pressure Gauge pipe on top of a vessel was not screwed in properly or threads let go. 3' length of 2" pipe does a lot of damage to a lot of things! The Nameplate shouid give you data on the original Hydrostatic test Pressure. Normally 1.5 times Operating Pressure. 125 Psi rating would be tested at about 190 PSI.
When I was in the Air Force we did some pressure testing on some tanks about the size of yours, but we were required to go around all the welds and tap them with a ball peen hammer. It made me nervous, but when you encountered a leak it was uneventful. You just got a little wet.
Im all for the diy but as long as the correct tests applied for the tank. For a start the name plate or stamp should state the standard the tank was built, probably an ASME Section VIII tank, so you would follow UG-99 standard hydro static test procedure. At a min some of the test points are below: Test at least 1.3 x MAWP (name plate) Pt = 150psi*1.3*LSR ~ 200psi minimum for the tank in the video, if the plate test pressure is 200psi its probably a 150psi max tank (dont confuse MAWP and test pressure). We dont know the exact test temp and material design temp and stresses so LSR is fudged here ~2-10% since its tested with cold water. Dont over pressurize a tank during the test as you could actually push it to yield. The tank design and test is meant to keep it well in the elastic region when its first built, tanks have safety factor and corrosion allowance but defiantly loose wall thickness over time and are weakened with age and cycles. P inspection min = Pt /1.3 ~153psi, reduce the test pressure from 200psi to 153psi and do a visual inspection of the welds and joints for leaks, (dont go poking near a tank at test pressure). Test hold time is not specified for a hydro static test but it would be sufficient enough hold time to finish the visual inspection. One note of caution, UG-100 allows a pneumatic pressure test of tanks where a hydro test would not work. In that case P test = 1.1 x MAWP and its done in incremental steps. Always reference the MAWP to determine the actual test pressure. Not the case for compressor tanks though, they are readily able to be hydro tested so UG-100 test is forbidden in this case, but good to note. What the guy did in the video was more or less correct (for a compressor tank) but did not perform a visual check correctly, did not reference the test procedure (UG-99 test) and arbitrarily chose 1.5-2x because the tank can take it, confused it with ASME B31 process piping as a test pressure or boiler test pressure which is done at a higher multiple because the test fluid temperature is much lower then operating fluid temp of a boiler so the calculated LSR is much higher on a boiler then it would be on a room temp compressor. A cowboy kind of test approach in the video but within spec, and its better to test like this then not to test.
I'm about to do some tom foolery - but I'm glad I stumbled across this - Definitely going to give this a try to give myself some peace of mind with my repair lol.
Use a pi diameter tape measure when hydro testing your tanks, they cost less than $20. Measure the circumference of the tank in three spots, top, middle, and bottom before testing. Measure them again after hydro testing is complete. If the measurements are the same then you had no permanent deformation. On older tanks hydro testing can cause unseen deformation, so you basically stretched it out and actually weakened it during the test, leading to catastrophic rupture when put in use later.
I remember doing a 600psi test on a boil with a hand pump, dam it took time. But for air I do the same as you did but just use a cheep home electric one, and yes I have done a few. I also remember the day I used a pressure washer to save a 100 odd year old traction engine boiler that had both the mechanical water pump and the injector pump fail at the same time whiled heavy fired, when someone (and no not me) used a huge hose from a pump out of a dam, they pumped sludge into the tank. everyone was so worried and so I just found a quick connect and fitted it to the steam pipe and filled the boil with town water, it took a few minutes for the water to show on the gage glass but it did the job and saved the boiler, tho it needed a major clean out and retesting because of the event, but hey it worked.
we don't do pressure tests in my state, Washington. either the state inspector or your insurance inspector does an inspection with an ultrasonic thickness gauge. this has to be done every 2 years for any pressure vessel in commercial use or any above 80 gal.
I did this test twice, and my nerves are still shot every time i fire up the compressor, lol... I used to run 150 psi, but I don't fill truck tires nearly as often as I used to, so I cranked the regulator down to 120 cutout. But the test was run at 270 psi both times and the tank stayed silent and held each time for well over 30 minutes. The safety valve is currently rated at 175 but I plan to get a new one rated at 150 or 145 because this one is starting to leak and pressure governors/regulators (mechanical) can fail and I just want more piece of mind. I had already used the tank for a few years, just put some brackets on it to make it portable and mount the compressor and engine to.
If you were to measure the mid point diameter increase I wonder if it would be enough to emulate the results available from a full submersion volume increase test. I'm reminded of an interesting problem at a paint department. They had a fancy lacquer paint job on an old secondary air tank that helped to diagnose a collection of errors. In addition to their main compressor they bought a detuned to 175psi setup to provide high pressure whenever they ran their spot welder and through a series of plumbing and control mistakes over pressurized everything. This was during a rare BBQ lunch break when no one was around. A few older hoses had ruptured but the pumps managed to keep up long enough to trip a 225psi safety high pressure lock. My name was on the CSA document so I got the opportunity to sort it out, not that it matters. Their old secondary tank's lacquer paint job was full of tiny lines around the mid point indicating that cracks had formed. Everyone agreed they weren't there before. I don't know what pressure it actually shut down at but the safety switch was a fixed setting guaranteed to pop within a percentage, the new one says 2%. An old 150psi relief valve and two 200psi burst disks were pressured into accepting early retirement... with severance. An idea... A mid point diameter checking device could have a multiplier that made a dangerous increase easily noticeable or better yet detectable by a switch. You never know when a BBQ might happen.
Compressors are no joke my brother inlaws neighbor lost his arm when the person made the mistake of dead heading a air compressor which exploded injuring 2 adults in the garage where the accident took place
When compressed gas cylinders are hydro tested, they're monitored for volumetric changes by submerging the cylinder in a sealed water tank during the test. The amount of water expelled equals the volumetric growth of the cylinder under test, and you can also verify that the tank returned to its original size. This way, thin (corroded) walls are detected even if they don't rupture. I'm not suggesting you should do this in your situation, it just seemed like something of interest. Now we just have to figure out the optimum air/water ratio and bottom nozzle diameter to get that tank to rocket as high in the air as possible. I would like to start with 70% water and 30% air at 225 PSIG. If that's a 100-gal tank, a 3" nozzle should be good for a gentle lift-off, so I vote for 4" to launch with gusto. You can pull the cork!
I've always wondered about stress testing like this. How do you know that the test itself, exceeding the stresses of the intended application, doesn't weaken it and cause premature failure after one or more pressure cycles?
Thanks for some great and timely information. I have the exact same tank and am putting it in service after it sat a long time, now I know how to safely test it.
See? You just explained the problem with water cooled Nuclear reactors. They use pressurized water(very high pressure), which for every pound of pressure you get about 3 degrees increase of temperature before boiling (212deg F). So how much pressure for 600 Degrees F? In a building the size of a football field? Your car is happy with 30 psi in your tires, and they are rather small but carry thousands of pounds of weight. Molten salt is far better, and is happy at 700 deg C. Radiation isn't the problem compared to water explosions dispersing it. But I did come to this channel for the hydrostatic testing procedure, and appreciate it. Nice explanation, Sir.
The test shown is what DOT calls a low pressure hydrostatic test, it does not require measuring expansion. For this type of test, the cylinder is inspected internally for rust and corrosion, which should be mechanically or chemically cleaned, flushed and filled with water. The tank is then pressurized to the rated pressure for a minimum of 30 seconds without any leaking. If the pressure holds, the tank has passed the test and is good for 12 years before the next test. The pressurizing device should have a shut off valve to keep the pump from supplying water in the event of a cylinder failure, no big explosion, you just get very wet.
12 years? Is this a typo? If the tank is in an ASME code state, that states law determines time interval between tests but the insurance company has the say also.
@@garwilliams4937. From the Manchester Tank web site. " Built in accordance with the ASME Section VIII Division I code latest addition. Vessels are "U" stamped and registered with National Board" You misunderstood my 'L' remaek.
The quotes I have received for hydro-testing were more than the cost of a new tank. Having watched this video, I can now do my own test on my 100-year-old tank. I just have to figure out how to move that monster out of my garage. It took an engine hoist to get it in there.
For all the nervous Nellie's you need to search out "lpg cylinder burst test" (hydro pressure testing tank failure) on RUclips You'll see how undramatic it is when these fail with water in them. They bulge a LPG cylinder out with 1200+psi.
@Mike T what?? pressure can't build up with just water? how bout if it's filled with water and a grease gun pushing water or grease won't get it to a test pressure? i always thought it would, according to the gauge it did. i've only tried it on horizontal tanks. i got a few air compressors, get this, one of them my dad had since the 60s and it has a built in square tank that always cracked and he brazed it and added another tank under it, the weld cracks all the time and i braze it back up, it runs up to 120psi. i got a 30 gal boiler compressor tank and pump, it had some pretty bad cracks on the flywheel, and i v'd it out and arc welded it back together. it should work fine. i don't stand in the line of fire though. just hoping it don't go through the neighbors wall.
Keith you have a very humble dog that knows how to behave when there is a video cam running so he came really close to your garage house wall like " YEP I'M NOT GONNA BE IN THIS VIDEO SHOT " HE DID IT LIKE TAKING CARE OF NOT RUINING YOUR SHOT " !! HAHAHAHA AMAZING FUNNY DOG !!
Good practical information Keith a little surprised about the release of pressure after the test I assume that was from a small air pocket above the pressure gauge which you mentioned in the video.
we use to do pressure testing on hot water heaters and let me tell ya water is just as bad as air iv seen them explode and take 1/2 the house with it, it take 2 failures releaf valve stuck for both and ether the water pump pressure switch fails or the thermostat and they start to build pressure till they pop from 300psi to up to 1000psi at 300psi the tank can wipe out 1 floor above and below at 500psi and they will wipe out the 1 below and 2 above and at 1000psi they can rip 1/2 a 3 story house down. go watch some video of water heaters failing in 15yrs of doing hvac i seen only 3 times but its amazing the power they have when the pop. thanks for sharing
I think that, when the thermostat runs away, you have a steam vessel. Steam at atmospheric pressure is about 1000 times the volume of the water. I’m sure it’s damaging.
The main reason for testing at a higher safety margin for steam vessels is temperature so if you're testing with a cold liquid increasing the margin helps account for the fact that steam will heat the vessel and make it expand/affect it's metallurgical properties.
I bought an $85 Chinese Digital metal Thickness Gauge on Ebay. Checked it repeatedly against metal of known (and easily measurable) thickness. It appears to be quite accurate. Then I checked many spots on the bottom of my 1986 80 gallon Ingersoll Rand vertical Air Receiver. Several places on the tank bottom showed corrosion thinning down to 50% of the thickness indicated on the build plate. This tank was drained frequently from the day it was installed new.
I imagine if the corrosion has affected a weld or a long pit of corrosion causes a weak point and the tank rips open... and maybe combined that with an over pressure.
Losing that much thickness. The original manufacturers head thickness is shown on the "U" for the serial number of the tank from the National Board in Columbus, Ohio. If there was a corrosion allowance in the design, that amount is shown also. This is important to know for down rating the MAWP, scrapping or safely using.
Since moisture laying in the bottom of a tank is the most common point of failure when it rusts through I have often wondered why the manufacturers don't galvanize the interior? Is there some reason that wouldn't be viable other than the few dollars of cost? It is a given no matter how much or how often you drain the tank in such an oxygen rich environment (ten atmospheres or so), the fact moisture will always be present and that it takes so little to start and continue the oxidation process that this would be a problem that should be solved. Especially so since most drains have a welded in boss that is actually slightly higher than the bottom of the tank creating a reservoir of constant water. Nice project. Take care. Doug
The interior might BE galvanized, how would we know? But, whatever the manufacurer did, the tank seems fine after 30+ years, so it was... good enough. Welded tank seams would have to be complete, and clean on the inside of the tank, before galvanizing, though.
I like this idea. I'd make a few minor tweaks(Mostly being more careful about the air purge as others mentioned), but nothing really different. Love this idea. Very good about the 'pressure washers can go up to stupid high values, so be carefull' warning.. I can easly imagine someone just holding down the trigger and hydro-forming instead of hydro-testing their tank.. :)
If the working pressure in a tank is 175 psi, you figure out how many square inches of tank surface you have and multiply it by 175. This is how manty thousands of pounds of explosive pressure you have waiting. That's why some call portable air tanks "Air Bombs". If you pressure test get all of the air out. Keith should have had a helper to tilt the tank to get more air out. I was trained at Quincy Company over 40 years ago.
Good job. I bought an old Manchester pressure water tank (120 gal) for $70. I’m in the process of trying to clean the inside. But should I do this pressure test first? Either way? How would I clean the inside? I’ve seen fancy rollers (pitch) that roll abrasive material inside while slowly tilting (roll) to get the ends. But this beast is big. I’d rather find an easier way to scrub the inside. Thinking of Evap-o-rust followed by a wet sandblaster with my pressure washer. Then apply a rust stopper coating inside followed by epoxy resin. I just don’t know. You look like you know what you’re doing (except when you said “solid water 😬), so I’m asking you for advice. The tank is 40 years old and was being used as an air reservoir when I bought it. It has a lot of ports on it and a handle on top. Also has a drain valve underneath. Thanks for your attention. I like the quality of your work. (Max pressure inside will be 150 psi. It’s rated for 200). Paul.
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When I was an engineer working for a major oil company we used to hydrotest pressure vessels by filling them with hydraulic fluid or light oils (diesel fuel) and compress them up with a hand-pump (similar to what you see with a small hydraulic jack). We factored in the compressibility of fluids, temperature and something known as "the steel factor". Steel does stretch under pressure and it adds a fraction of a percent to the capacity of the pressure vessel and in a failure, that steel stretch will cause an outpouring (jet, spray, stream, etc..) at the point of failure. On some of the things we tested we operated at up to 2250 PSI (on 0.375 wall thickness steel) where things were connected with ANSI 600 flanges. The pressure had to hold for twelve hours and we had to record pressure to the fraction of a PSI and temperature of the vessel. On some of these systems it was for a 30 mile long segment of pipeline that had blind flanges added at the ends (or double block-and-bleed valves).
We had one notable failure on a 12" diameter pipeline that ruptured at a point where it was four feet underground. It blew a crater in the ground that looked like an artillery shell had gone off. The pressure at the end (where we were) dropped off very quickly but there still was enough dynamic energy in the system because of the steel-factor stretch.
"We had one notable failure ..." What was in the line that ruptured? Apparently a gas or something superheated.
Keith, long time lurker of your channel, here. I inherited a vintage Sears Craftsman air compressor and have been wanting to do some kind of hydro test on it just for, as another connector said, peace of mind. I didn't want to purchase any equipment that i would probably only use one, or pay to have a fully-certified test done, but as yet-another connector says, Ice seen the aftermath of a small shop compressor blow-out due to a rusty tank and I'd just feel safer with literally ANY test. I had no idea i could potentially use my little pressure washer as a pump, it never occurred to me, so thank you for that! I likely won't push the old thing over 150, I'll probably never use it for more than 80-100psi but i have over 4 decades of find memories for it and i want it to run again.
When they hydro test high pressure gas cylinders they get pumped up with water to the test pressure but at the same time they measure the expansion of the tank under the test pressure. The test I watched was done by placing the test tank inside another unpressurized tank filled with water. As the test cylinder expanded it displaced some of the water in the outer tank. The displaced volume was recorded by reading a site glass affixed to the top cover of the testing tank. They were looking to see that when the when the pressure was released, the cylinder returned to its original volume (shape). and there was no peppermint deformation to that tank being tested. If the sight glass didn't return to the same starting point that indicated the tank had exceeded the elastic limits and had failed the test even though it didn't leak. Continual cycling such a thank would cause it to eventually fail.
Craig that is done on high pressure tanks like oxygen, nitrogen, dive tanks etc. When I was working at a company that used a lot of tanks I often saw tanks delivered that were manufactured in WWII and a few as far back as WWI. They had many cycles and been pressure tested many times. Although there was a series of dive tanks that were known to fail near the neck.
Yup, that was because they used the wrong aluminum alloy (6351-T6) in manufacturing. The neck would develop micro cracks and then fail. We had a lot of them in the fire service as well. Did a lot of hydro testing of SCBA tanks over the years.
Those are tested using an eddy current test, visual inspection and then hydro tested if they pass those two first. We just took them out of service, cut them up and scrapped them. Not really something you want strapped on your back if it fails... Have seen the results of that, not a good thing to see...
Peppermint deformation?? Damn you, auto-correct! :-)
I agree totally with this. Some should be careful as what they are posting on RUclips
@@marcbeaudry9084 Post safety disclaimers at the least.
I'm glad I watched this before putting a used air compressor back into service! I've seen air tanks fail before with compressed air and one took off like a rocket and banged into the shop ceiling, doing lots of damage - and could have killed someone if they were standing nearby!
Great job - I would never have thought of using a pressure washer to test it.
Well Sunny beaches! I had a 80 gal tank that rusted through so I found one for 200.00 now when I was not to sure of the tank and wanted to test it. I read about people suggesting water test it, when I did not know who would do it I saw my pressure washer sitting there. After about fifteen minutes I found a quick air connector and put it on the pressure washer. iI figured maybe leave about a cubit foot of air in it and fill it with water, then I thought let’s see what RUclips says about it. Wow found this video! Doing the same thing! God is Good!
i do a lot of hydro pressure testing here in the UK on check valves for the gas and oil industry when doing a test like this with large volumes of water please still take care because if you do have a failure of the tank or any of your fitting you will be surprised at the results as you can see when Keith let the pressure out at the Bottom of the tank if that had being a fitting coming off you would know about it i do pressures from 350 psi up to 15000 psi on Hydro so have plenty of experience with this type of testing it is safe but you still need to take care ENGAGE SAFETY SQUINTS and i would have put my self behind something when doing this test please do not think i am having a go at Keith but unless you witnessed a test go wrong or had one your self go wrong like i have last year when a gasket let go at 4.500 psi you then have a lot more respect for any type of pressure testing (yes i know it was only 250 psi ) but it will still hurt so take care
@@bottomlands I have found through my journeys in life people who care about punctuation and lord it over people lack practical knowledge of the world and cannot actually do what they are critiquing.
Iff you use punctuation to prove you superiority you are infact inferior and most likely insecure.
That being said. I helped my uncle jack off a horse.
I helped my uncle jack, off a horse.
Witch one is correct? 🤔
If you can't understand what he's trying to say without punctuation your going to find life a real struggle
@@frankinjeep1194 Wow, All you did there is prove what a self righteous douche bag you are! lmao
@@dept.ofredundancydept.94 I'm just tired of grammar police. Its RUclips not English class. And yes I'm an ass hole.
@@bottomlands have you ever written a hydro test procedure for a 25 mile DOT pipeline or actually tested and inspected a hydro test?
I have for the last 15 years. Have you ever over seen a 1.8 million dollar project? I am right now. Do you have an IQ of 145 ? I do. My point is dont dennagrat some one over punctuation English may not be his first language. When people try to run a person down over small stuff they don't get the big picture.
Very well explained . Being a boiler plant engineer safety and annual testing is paramount . Few non pros would perform a wall thickness deterioration test on an air receiver ( a good idea after 10 years ) but ya could remove the large bung plug ( most have one ) and do a visual with a borescope or drain camera .
Scrapyard?! Come on Keith, no respecting southern boy would scrap that tank. It's the new BBQ smoker at the deer camp!
exactly!
@@johnbrian118 If it blew like a boiled sausage it wouldn't be good for that either... ;)
@@jackmclane1826
It wouldn't during the hydraulic test.
@@calvingreene90 True, but this wasn't a purely hydraulic test. The air cussion at the top was enough to be violent in case of a rupture. See how the water shot out at the end...
Still a lot better than a pure air test.
@@jackmclane1826
There was the little air bubble but it was mostly the steel's elasticity. The plastic deformation from rupturing would have been slightly more than a pure hydraulic test but not enough to ruin it for making a smoker.
My Jr high school shop teacher had an air tank that had ruptured when filled with air hanging on the wall. I don't underestimate the power of compressed air.
Lol, the dog walked off into the woods for cover during the test and strolled back when it was over.
It was not his first rodeo. Did you see the greybeard on the ole boy?
Like us little kids when dad used to turn on the table saw.
Dude hell yeah! There's nothing like old man knowledge. I just bought an old air compressor but that tank hadn't been drained of water so now I'm scared to pump it up. Now I can test it without spending an arm and a leg at some shop!
Having done countless hydro tests of piping systems I want to add a couple of points.
First, respect pressure. All things equal it is true that the dangers of air testing far outweigh hydrotesting but dangers exist any time anything is under pressure.
Second, the leak at the gauge is a great visual. Most hydrotests fail because the test apparatus leaks.
No doubt! I was working on a wetland restoration project 12 years ago and a hose about 2-3 times the diameter of a fire hose that supplied water to a hopper used for making slurry blew. up right in front of me… and I didn’t even touch it! Needless to say, it threw me on my ass at least 10’ away from where I was standing! Yeah! Definitely respect pressure!
I enjoyed your video immensely, and have a compressor tank of my own, purchased second hand, that requires testing. Thank you.For all the 13 year old 'experts' and 'keyboard kommandos' out there here is the procedure used in the fire service, their LIVES depend on compressed air tanks."Requirements For Hydrostatic Tank Testing:1. Hydrostatic tank testing must be completed by a licensed certified tank tester with special equipment designed for the task.
2. The tank should be tested every five years.
3. The tank must be tested more often than every five years if there are any visual signs of degradation or damage.
4. Requirements under the law state that the tank to be tested must be filled with water and pressurized to 167% of the maximum operating pressure listed on the side of the tank.
5. The tank, including all of the valves and other closures, must hold the pressure test for at least 30 minutes without leaking or bulging.
6. Details and requirements for hydrostatic testing are covered under OSHA regulations section 180.407."
I had the horrible experience of being a pall bearar at a coworker's funeral. He was killed during a hydro test of a piping system. A hose broke and he was struck by water from the hose. There was a pocket of air in the pipe which added to the thrust of the water coming from the pipe.
Lessons learned included included; hard piping all connections, making sure all pipes and vessels were filled 100%, using equipment intended and used exclusively for pressure testing, and keeping unauthorized personnel away from test connections.
Good safety practices are required both at work and at home. Whether it be welding, cutting way wipers with a small bandsaw, pressure testing a compressed air receiver, or any other shop activity safe practices need to be followed.
Bob
Keith - Thanks for making this episode. I looked at my compressor which sits in a corner of the basement with air lines to my nearby work bench and the garage. Couldn't recall the last time I drained water from the tank. Even forgot I had installed a radiator petcock in the drain! So it's been a while. The water that drained out was pretty clear and less than a quart BUT that compressor was manufactured in 1970! The 2 cylinder cast iron compressor is getting pretty tired. I replaced some reeds about 5 years ago. But it's struggling again so I'm retiring the old girl.
Picked up a smaller unit at (sorry!) Harbor Freight - 8 gallon vs. 20 on the old Sears BEST unit. I noticed that every compressor in the store recommends draining the tank every day after use.
When I pressure tested my old Quincy 50 gallon tank a few years back I just filled it to the top with water and put a liquid pressure gauge on it.... I then made sure all the air was out and I capped it and left it in the sun. The heat soaked tank slowly built pressure enough to successfully test it. Works great as long as you have a sunny day.
This was a random video picked by RUclips
Thanks
I never knew how they tested Compressor tanks
How do they rustproof the insides ????
thank you for the idea of using the pressure washer, I am in the middle of testing a intake manifold on a boat engine that had coolant in the oil I traced it to the intake, so before adding the oil and coolant I want to test it, thanks again
At Ball Aerospace, outside of Boulder Colorado, they had a facility that tested tanks. They were doing a repeat pressurization test, putting the tank in question through multiple cycles of pressure, and failed to realize that some of the water escaped with each venting of the tank. When the tank failed after several days of testing, the top half went through the roof and about 200 feet in the air.
I used to work at Ball in Boulder. Optical design. Never saw the facility you speak of. But that’s no surprise.
Really. I wonder where Ball gets their special compressible water for such tests. They certainly don't sell that on McMaster-Carr.
@@Kandralla Read it again, slowly this time. You'll understand eventually.
Great way to have peace of mind that the pressure tanks is alright to use. I watched a video yesterday where a mechanic showed the aftermath from a compressed air tank failure. The shop was in disarray, with holes on the wall, & door, as well as all windows busted!
I came here from that same video
Keith i appreciate your video! i have an old sears air compressor from the 70's unfortunately there is a chunk out of the crank keyway and when i contacted campbell hausfield (who made the pump for the compressor) they wanted to sell me a new pump! After that they wanted to remind me of the safety of an old tank. Now i can hydro test mine mine though i pulled the inspection plugs and looked in the tank!
Informative video; I've had refrigerant recovery tanks "hydro-tested" for recertification, never really liked the idea of introducing water into a refrigerant tank. Now I understand the thought process of using water (safety factor) instead of another medium. Water & refrigerants shouldn't be exposed to each other, causes all sorts of problems inside a refrigeration circuit. I guess I have to trust whomever is hydrotesting the tanks properly dries the interior completely before shipping it back to me. I believe a deep vacuum pump (6 CFM or greater) drawn down to less than 100 Microns vacuum is an additional "no worries" about water inside the vessel. Good video, liked the presentation!
Thank you for clarifying that age-old incorrect statement that "water is not compressible". While it certainly has MUCH, MUCH lower compressibility than "air", it absolutely is compressible... and making a working test fixture that does so (to over 27 bar) has been a serious learning experience in physics.
The small air pocket at the top is actually useful, as that small amount of compressibility, allows the pressure to ramp-up slower. If the tank was completely full and you hit it with 3000psi, then the internal pressure would have risen very fast and it would be difficult for you to set the gauge to 225psi. :)
I can confirm that. I had (virtually) no air pocket in my tank and the pressure meter immediately went off the chart. I mean: way faster than in this video. I'm glad I had read this warning (and the one in the video)
Many, many years ago a friend of my fathers walked into his body shop to find the pump and motor from his compressor setting on the floor by a large hole in the wall. Most of the tank was found in a corn field about 1/4 mile away. All of the tank peaces were never found.
I forgot who i saw do this, but a grease gun can be used to add pressure to a tank full of water. Love the channel, thanks.
I think AVE does a video with the grease gun hydro set up.
Thank you Keith! I'm looking to buy an older 360 gallon horizonal tank, and this is a great start. If it has the larger bung I'll have pros look at it, but never in my life would I have thought to use my pressure washer in this manner. I thank you for your video!
That was interesting, always wondered how I could hydrotest a tank. Thanks
Fun, in the first few second it thought, “what is that little fence on top...” 🤪
Hey Keith,
Thanks for making this video. I was watching The Compressor Guru and he mentioned how you do a Hydro test. I posted this question on his channel and I would like to get your opinion.
I would like to ask a question, what is the importance of draining the tank every day? I understand water and metal don’t get along with each other, but as soon as you turn these things on condensation starts to build up and pools at the bottom. So even if you drain it every day you’re not going to get 100% of the water out and it’s always gonna be damp inside which is going to promote rust.
Thanks!
God bless!!
Blue
I love the disclaimer for the solid water remark
Hi. My late Dad worked for the pumps and compressors division of a globally well known firm. He had some stories about what happens if the valve breaks off a high pressure air cylinder. The air blast from a 3,000 psi one can cut a man in half. If the tank breaks free you have a high power rocket with a mind of its own. Even at one twentyth of that pressure an air or gas cylinder air filled explosion is potentially lethal. That's why there's a 150% oveload water test. In fact, the cylinder expansion should also really be measured occasionaly as over time repeated filling and emptying will lead to fatigue failure. This is a madatory requirement for things like diver's air cylinders. Drain the tank of condensed water vapour regularly, you REALLY do not want it rusting from inside out. It's instructive to multiply the tank pressure by the inside surface area to find out the forces involved. They may suprise you. Incidentally Keith is mentioning 'pounds' a lot when he really means 'pounds per square inch'. But, it's very good of him to raise this subject. It's important. BobUK. (edit to correct my spelling).
You are speaking of the principle that air bags use to lift heavy objects and pneumatic cylinders use simple low air pressure to operate valves over a large surface area. It is all in how one contains the pressure for work or to service that work. BTW, the just the sound a tank exploding makes from weakening due to rust will definitely get your attention.
Yes, know of a case where the oxygen cylinder in a welding set fell off and broke off the valve. Went through 3 floors of a concrete building, and also through one unfortunate standing on the one spot.
Nice easy test setup there Kieth! I imagine it would have done the full amount but it is an old tank and a test like that might cause a future failure.
The thought of a tank like that exploding is pretty scary. Thanks I enjoyed the video.
I'm restoring a ProAir 80 Gallon 6.5 HP 175 PSI now. It was not locked up but had some build up in the 2nd stage cylinder bore that would stop the piston a 1/2 inch from the top and not letting the piston make its full revolution.
I've replaced the tank check valve, cleaned the bore to where it turns freely, replaced one capacitor and ran it with an open valve for ten minutes yesterday.
I was going to do the same thing today and it popped the run cap on startup. That was a 2005 cap so I've got one ordered for it along with the oil filler breather cap. We used it for years at our Pipe Construction garage.
An old tank is always sort of scary though. It is in very good shape though so I'm not to worried about the tank.
Tanks a million for your video , as it is good to know how to test these vessels.
Cheers from John in Australia.
Thanks Keith. Very thoughtful presentation. When you brought that old compressor home I was hoping you would test the tank. Most people would have just let it rip and hope for the best.
Valve Monky covers the essentials below Keith, it is his specialist subject, and mine.
If you were doing it again;
Tilt the tank till the vent is at the high spot, trapped air is your enemy.
Put a positive shut off valve in circuit to hold the pressure in.
Working pressure only when retesting an old unit, 200psig would be fine.
Remember to test and re-calibrate the relief valve - this is actually more important than hydro testing the receiver.
... and before you test it - ding it with a hammer, and if it goes 'clunk' rather than 'clang', just scrap it.
Because he was using a pressure washer, a *small amount* of trapped air is extremely necessary. It's a compressible buffer that allows you to add pressure in a somewhat controlled manner in the absence of a pressure regulator valve. Notice how the pressure rose very quickly and he over-shot his target. With no air buffer it could have spiked to the full output almost immediately.
It is quite exciting hearing the pops, snaps and other sounds, doing a burst-test on a test-specimen. I have done that :) We pumped up the specimens to 135 bar, before they leaked, no explosion at all with water. Just a pissing little leak of clean water. Of cource, just a little little bit of air was trapped during the test.
Good for 25 bar, the design that is. The test specimen destroyed.
Non-destructive testing is performed at 1,33 x MAWP (Maximum Allowable Working Pressure) as I recall it, cold or @ 20°C, save for higher temperature curves according to the material properties in question.
I did this about 50 years ago, before homeowners had pressure washers, by filling the tank almost completely with water and then using the air compressor to pump it up to 200 psi. I doubt that I had more than a cupful of space with compressed air. No problem.
It would be interesting to poke a borescope inside and see what inside of the tank looks like in terms of corrosion.
That's exactly what I thought as well - I can just image the inside condition of the bottom of the tank especially if the original owner didn't drain the water regularly. It's going to be a rust bucket. Using a borescope is almost the very first test on any pressure vessel.
The good thing about vertical tanks, is that moisture collects at the domed bottom of the tank, unlike a horizontal tank.
I had a 50 or so gallon Sears Craftsman air compressor with the horizontal tank marked as being built in 1949. I had no history of the unit when purchased. I owned it for better than 25 years before it developed a pin hole leak at a welded seam.
The old Craftsman compressor was retired to become a BBQ smoker, and I purchased a 80 gallon, 5hp Ingersoll Rand vertical tank model.
It passed the pressure test. Not enough corrosion to worry about. And if Keith drains the condensate from the tank on a monthly basis, no worries in the future.
If there was significant corrosion it would have showed up when the receiver was drained. Not a definitive test to be sure but if it passes the squeeze then it's good.
He didn't ring it like a bell to set off any stress fractures.
Nice explanation! The comments are interesting as well. Also, I was thinking if the remaining air in the tank mattered, possibly tilting the tank so that bung where you put the gauge was at the highest point while filling with the water to push the remaining air out. If it even matters. Thank you and May God Bless.
Got the same tank and I did the same hydraulic testing to over 300 PSI. I feel safe as well. Nothing like piece of mind
Wow, Thanks, That was a great idea and I have learned a nice and safer trick. Wish this grandfather had done this test first, You can search Air Tank exploding on youtube and the explosion was caught on CCTV, The gentleman survived but was in the hospital for 2 months, Thanks again for the idea. The water would just scare the crap out of you but the air test would cut the crap out of you if it failed.
Because water is non-compressible it builds pressure much faster than air for anyone wondering how it built pressure so quickly. For air to build the same pressure you would need to pump in many cubic feet of air, with water it only holds what it holds so you are simply trying to force in more than it will hold and it instantly builds pressure because no more water can fit inside so the pressure is from the cylinder or tank slightly expanding, in this case there is a small amount of air at the top which is compressing too.
When testing any pressure vessel in your yard OSHA requires you to utter the phrase “ here, hold my beer and video tape this “ to your buddy. If a buddy is not available then a nervous girlfriend ( a proper wife would never help you with this ) or your home security system will do and make sure your recording devices are not password protected so the internet can enjoy the results.
For those with a pressure washer in their butt , this was a joke.
A bad joke in poor taste. (This is sarcasm, you mental midgets.) I liked it. And to all you PC people out there, PO.
Plus you have to say "watch this"..usually after several beers.
I think in the south the correct OSHA phrase starts with "Hey Y'all..................
One way to do this is just pump it up to max capacity with air, then set it vertically on a big pile of dry wood and then light the wood on fire. And then very quickly drive about a half mile away and try and catch it when it drops back in from orbit. I call this the maximum apogee tolerance test.
Good thinking to do hydro testing . I did considerable amount of air-testing to failure and few can imagine the destructive ability of even a medium size vessel when the failure occurs even at rather low air pressures . It is hard to over-engineer the confinement chambers necessary to contain the "shrapnel" as the result of the ultimate failure . Most of the time even the confinement chambers are partially destroyed . Air-testing is indeed life threatening !
Thanks for making a good education source me and my sons can get something from.... good work. 👍
I find these lower than tag rated home tests amusing.
I've done many tank tests with old odd scrap yard or auction air, propane and other tanks I have picked up over the years and repurposed or added ports to or modified in some way and I have always done my test to 2x rated for a at minimal 10 minute hold and even done a few to 3x and 4x to push dents out.
Never had one catastrophically fail either (I do stand around a corner and pressure them up remotely though) even with very rough looking air and propane tanks with build dates going way back into the 1940's!
Always so pleasant and knowledgeable. Thanks for sharing. I always learn something from your videos.
The pressure washers I've used had a pressure gauge and pressure adjust valve. I'm a fan of cranking the valve down to zero and then back up to about the limit value I want before doing something like this, rather than bumping the wand valve on something set to 3000psi.
I love Mondays and Fridays.
well i did not think that my comment would turn in to such a bun fight. just got in from work don't know what's more dangerous high pressure testing or making a comment on You tube ! .
It brings the self-righteous subject police out of the woodwork. Just like the punctuation police, that's all they know about!
crazy huh? youtube brings out the best of em. gotta keep in mind some of us like Keith didn't have internet nor much of instruction manuals, nor could a lot of read well, but somehow with all the crazy stuff we did, we made and by the way, things in the past were built a lot better. like my dad he had a second sense about building everything with maximum overkill. everything worked and lasted longer than he did. today with all the warnings based on harbor freight junk as the leader in tools for these poor kids to place their trust in, makes me wonder, so that is what their standards are built on. to them it's the deal, i mean it smells like tools when you walk in, but that's as close as it gets. i used to think those flash lights that harbor gave away was ok, but they're trash too.
I tried to get a new tank for my 80 gal compressor. The total cost, including shipping, was about the same as a complete brand new Ingersoll-Rand 480 lb compressor. Good luck with that old tank.
I was replacing a jammed safety relief valve on a hot water tank once. I stupidly did not release the water pressure on the unit and the damn fitting shot across the room with quite some force the moment I was done unscrewing it. It was just residential, so probably not more than 30 psi on it. I've also cut into plenty of water supply pipes while forgetting to depressurize... (seeing a pattern, eh?) When it's just water shooting at you it's just fun and giggle, like Keith says. The thing you want to be careful of is any fittings or similar coming loose for whatever reason during your test. Those could easily knock out teeth.
Home Brew Hydro Testing using a Pressure Washer, Gotta Love It.
When I was with the Genesee County Parks & Recreation Commission we used a weed sprayer to hydro test air tanks. We would adjust the pressure regulator for the pressure we wanted.
Well done Keith. Some important points. Never screw in a gauge by the gauge body. Always use a wrench or you will damage the gauge. After filling the tank, always let the temperature stabilize. Preferably stand behind a wall when pressurizing. That dog didn't get old by being dumb! The leg of my small 3 gal tank is stamped with a "Destroy By" date.
Sadly the cheap drains are a coupling welded in that protrudes Inside the tank, and does not allow complete drainage of any condensate. Never buy one at a Garage Sale! I have done countless Hydro tests and once witnessed a pipe coupling failure and 3,500 psi. Impressive. Pressure Gauge pipe on top of a vessel was not screwed in properly or threads let go. 3' length of 2" pipe does a lot of damage to a lot of things! The Nameplate shouid give you data on the original Hydrostatic test Pressure. Normally 1.5 times Operating Pressure. 125 Psi rating would be tested at about 190 PSI.
Nice to be here. Lance & Patrick.
Great information Keith thanks for sharing 👍
When I was in the Air Force we did some pressure testing on some tanks about the size of yours, but we were required to go around all the welds and tap them with a ball peen hammer. It made me nervous, but when you encountered a leak it was uneventful. You just got a little wet.
Im all for the diy but as long as the correct tests applied for the tank. For a start the name plate or stamp should state the standard the tank was built, probably an ASME Section VIII tank, so you would follow UG-99 standard hydro static test procedure. At a min some of the test points are below:
Test at least 1.3 x MAWP (name plate) Pt = 150psi*1.3*LSR ~ 200psi minimum for the tank in the video, if the plate test pressure is 200psi its probably a 150psi max tank (dont confuse MAWP and test pressure). We dont know the exact test temp and material design temp and stresses so LSR is fudged here ~2-10% since its tested with cold water. Dont over pressurize a tank during the test as you could actually push it to yield. The tank design and test is meant to keep it well in the elastic region when its first built, tanks have safety factor and corrosion allowance but defiantly loose wall thickness over time and are weakened with age and cycles.
P inspection min = Pt /1.3 ~153psi, reduce the test pressure from 200psi to 153psi and do a visual inspection of the welds and joints for leaks, (dont go poking near a tank at test pressure). Test hold time is not specified for a hydro static test but it would be sufficient enough hold time to finish the visual inspection.
One note of caution, UG-100 allows a pneumatic pressure test of tanks where a hydro test would not work. In that case P test = 1.1 x MAWP and its done in incremental steps. Always reference the MAWP to determine the actual test pressure. Not the case for compressor tanks though, they are readily able to be hydro tested so UG-100 test is forbidden in this case, but good to note.
What the guy did in the video was more or less correct (for a compressor tank) but did not perform a visual check correctly, did not reference the test procedure (UG-99 test) and arbitrarily chose 1.5-2x because the tank can take it, confused it with ASME B31 process piping as a test pressure or boiler test pressure which is done at a higher multiple because the test fluid temperature is much lower then operating fluid temp of a boiler so the calculated LSR is much higher on a boiler then it would be on a room temp compressor. A cowboy kind of test approach in the video but within spec, and its better to test like this then not to test.
I'm about to do some tom foolery - but I'm glad I stumbled across this - Definitely going to give this a try to give myself some peace of mind with my repair lol.
This is a really great idea Keith and one I will be putting to use myself soon. Thanks for posting.
Use a pi diameter tape measure when hydro testing your tanks, they cost less than $20. Measure the circumference of the tank in three spots, top, middle, and bottom before testing. Measure them again after hydro testing is complete. If the measurements are the same then you had no permanent deformation. On older tanks hydro testing can cause unseen deformation, so you basically stretched it out and actually weakened it during the test, leading to catastrophic rupture when put in use later.
Excellent explanation and demonstration.
I remember doing a 600psi test on a boil with a hand pump, dam it took time.
But for air I do the same as you did but just use a cheep home electric one, and yes I have done a few.
I also remember the day I used a pressure washer to save a 100 odd year old traction engine boiler that had both the mechanical water pump and the injector pump fail at the same time whiled heavy fired, when someone (and no not me) used a huge hose from a pump out of a dam, they pumped sludge into the tank.
everyone was so worried and so I just found a quick connect and fitted it to the steam pipe and filled the boil with town water, it took a few minutes for the water to show on the gage glass but it did the job and saved the boiler, tho it needed a major clean out and retesting because of the event, but hey it worked.
You just answered all my questions in one video 😊
Thanks again Keith, was wondering what had happened to that tank! Good to see you are being "safe" as best you can! Enjoy your day my friend!
we don't do pressure tests in my state, Washington. either the state inspector or your insurance inspector does an inspection with an ultrasonic thickness gauge. this has to be done every 2 years for any pressure vessel in commercial use or any above 80 gal.
Thanks go the magic of TV we didn't have to wait like you did to fill that sucker up with water. It's a neat setup for testing.
I did this test twice, and my nerves are still shot every time i fire up the compressor, lol... I used to run 150 psi, but I don't fill truck tires nearly as often as I used to, so I cranked the regulator down to 120 cutout. But the test was run at 270 psi both times and the tank stayed silent and held each time for well over 30 minutes. The safety valve is currently rated at 175 but I plan to get a new one rated at 150 or 145 because this one is starting to leak and pressure governors/regulators (mechanical) can fail and I just want more piece of mind. I had already used the tank for a few years, just put some brackets on it to make it portable and mount the compressor and engine to.
Tanks for showing us that
If you were to measure the mid point diameter increase I wonder if it would be enough to emulate the results available from a full submersion volume increase test.
I'm reminded of an interesting problem at a paint department. They had a fancy lacquer paint job on an old secondary air tank that helped to diagnose a collection of errors. In addition to their main compressor they bought a detuned to 175psi setup to provide high pressure whenever they ran their spot welder and through a series of plumbing and control mistakes over pressurized everything. This was during a rare BBQ lunch break when no one was around. A few older hoses had ruptured but the pumps managed to keep up long enough to trip a 225psi safety high pressure lock. My name was on the CSA document so I got the opportunity to sort it out, not that it matters. Their old secondary tank's lacquer paint job was full of tiny lines around the mid point indicating that cracks had formed. Everyone agreed they weren't there before. I don't know what pressure it actually shut down at but the safety switch was a fixed setting guaranteed to pop within a percentage, the new one says 2%.
An old 150psi relief valve and two 200psi burst disks were pressured into accepting early retirement... with severance.
An idea... A mid point diameter checking device could have a multiplier that made a dangerous increase easily noticeable or better yet detectable by a switch. You never know when a BBQ might happen.
Compressors are no joke my brother inlaws neighbor lost his arm when the person made the mistake of dead heading a air compressor which exploded injuring 2 adults in the garage where the accident took place
don't they x ray the fittings? or is that only on breathing gas tanks?
That was a SOLID test.
Something practical that most can do at home. Thanks Keith!
When compressed gas cylinders are hydro tested, they're monitored for volumetric changes by submerging the cylinder in a sealed water tank during the test. The amount of water expelled equals the volumetric growth of the cylinder under test, and you can also verify that the tank returned to its original size. This way, thin (corroded) walls are detected even if they don't rupture. I'm not suggesting you should do this in your situation, it just seemed like something of interest. Now we just have to figure out the optimum air/water ratio and bottom nozzle diameter to get that tank to rocket as high in the air as possible. I would like to start with 70% water and 30% air at 225 PSIG. If that's a 100-gal tank, a 3" nozzle should be good for a gentle lift-off, so I vote for 4" to launch with gusto. You can pull the cork!
I want to be there!
I've always wondered about stress testing like this. How do you know that the test itself, exceeding the stresses of the intended application, doesn't weaken it and cause premature failure after one or more pressure cycles?
Thank you Keith!
Thanks for some great and timely information. I have the exact same tank and am putting it in service after it sat a long time, now I know how to safely test it.
See? You just explained the problem with water cooled Nuclear reactors. They use pressurized water(very high pressure), which for every pound of pressure you get about 3 degrees increase of temperature before boiling (212deg F). So how much pressure for 600 Degrees F? In a building the size of a football field? Your car is happy with 30 psi in your tires, and they are rather small but carry thousands of pounds of weight. Molten salt is far better, and is happy at 700 deg C. Radiation isn't the problem compared to water explosions dispersing it. But I did come to this channel for the hydrostatic testing procedure, and appreciate it. Nice explanation, Sir.
Great looking Golden. We lost our 'golden girl' last year.
The test shown is what DOT calls a low pressure hydrostatic test, it does not require measuring expansion. For this type of test, the cylinder is inspected internally for rust and corrosion, which should be mechanically or chemically cleaned, flushed and filled with water. The tank is then pressurized to the rated pressure for a minimum of 30 seconds without any leaking. If the pressure holds, the tank has passed the test and is good for 12 years before the next test.
The pressurizing device should have a shut off valve to keep the pump from supplying water in the event of a cylinder failure, no big explosion, you just get very wet.
12 years? Is this a typo? If the tank is in an ASME code state, that states law determines time interval between tests but the insurance company has the say also.
@@larselder874 If the tank has a DOT symbol or number on it, the rules I quoted apply.
@@garwilliams4937. From the Manchester Tank web site. " Built in accordance with the ASME Section VIII Division I code latest addition.
Vessels are "U" stamped and registered with National Board" You misunderstood my 'L' remaek.
Hey Keith, where did you find the quick disconnect fitting you used on the tank ?? I can't find one anywhere .
You're right about the compressibility of water. You'll experience much more flexing by the tank stretching, than by water compressing.
Great video! What kind of fitting did the pressure washer wand hook up to? Thank you!
The quotes I have received for hydro-testing were more than the cost of a new tank. Having watched this video, I can now do my own test on my 100-year-old tank. I just have to figure out how to move that monster out of my garage. It took an engine hoist to get it in there.
For all the nervous Nellie's you need to search out "lpg cylinder burst test" (hydro pressure testing tank failure) on RUclips You'll see how undramatic it is when these fail with water in them. They bulge a LPG cylinder out with 1200+psi.
Hydrotesting isn't explosive as water is, for all practical purposes, non compressible. Two different beasts.
@@stevenbiars4817 Yes, but as someone pointed out, a fitting coming off under pressure CAN be pretty dangerous.
@Mike T what?? pressure can't build up with just water? how bout if it's filled with water and a grease gun pushing water or grease won't get it to a test pressure? i always thought it would, according to the gauge it did. i've only tried it on horizontal tanks. i got a few air compressors, get this, one of them my dad had since the 60s and it has a built in square tank that always cracked and he brazed it and added another tank under it, the weld cracks all the time and i braze it back up, it runs up to 120psi. i got a 30 gal boiler compressor tank and pump, it had some pretty bad cracks on the flywheel, and i v'd it out and arc welded it back together. it should work fine. i don't stand in the line of fire though. just hoping it don't go through the neighbors wall.
Hi mate, thanks for showing us how to do hidráulic test
Keith you have a very humble dog that knows how to behave when there is a video
cam running so he came really close to your garage house wall like " YEP I'M NOT GONNA BE IN THIS VIDEO SHOT " HE DID IT LIKE TAKING CARE OF NOT RUINING YOUR SHOT " !!
HAHAHAHA
AMAZING FUNNY DOG !!
Good practical information Keith a little surprised about the release of pressure after the test I assume that was from a small air pocket above the pressure gauge which you mentioned in the video.
Yeah that was my thought too. It expanded and forced the water downward for a moment.
we use to do pressure testing on hot water heaters and let me tell ya water is just as bad as air iv seen them explode and take 1/2 the house with it, it take 2 failures releaf valve stuck for both and ether the water pump pressure switch fails or the thermostat and they start to build pressure till they pop from 300psi to up to 1000psi at 300psi the tank can wipe out 1 floor above and below at 500psi and they will wipe out the 1 below and 2 above and at 1000psi they can rip 1/2 a 3 story house down. go watch some video of water heaters failing in 15yrs of doing hvac i seen only 3 times but its amazing the power they have when the pop. thanks for sharing
I think that, when the thermostat runs away, you have a steam vessel. Steam at atmospheric pressure is about 1000 times the volume of the water. I’m sure it’s damaging.
you're a good man keith, do enjoy your videos.
That tank looks amazing for being 35 years old!
new paint
The main reason for testing at a higher safety margin for steam vessels is temperature so if you're testing with a cold liquid increasing the margin helps account for the fact that steam will heat the vessel and make it expand/affect it's metallurgical properties.
Carbon steel metalurgical / mechanical are AOK thru 650 degrees F. Critical pressure steam is 3,006 PSIG and yes, I have photos of a leak. serious.
Good example of how to do this.
Thanks,
John
That was fantastic information, thank you
I bought an $85 Chinese Digital metal Thickness Gauge on Ebay. Checked it repeatedly against metal of known (and easily measurable) thickness. It appears to be quite accurate. Then I checked many spots on the bottom of my 1986 80 gallon Ingersoll Rand vertical Air Receiver. Several places on the tank bottom showed corrosion thinning down to 50% of the thickness indicated on the build plate. This tank was drained frequently from the day it was installed new.
steel is neet stuff. It will form a cell and crrode through at that point resulting in a leak versus an explosion.
@@forbesmathews89 That's great! So explain some explode then if that's the case?
I imagine if the corrosion has affected a weld or a long pit of corrosion causes a weak point and the tank rips open... and maybe combined that with an over pressure.
Losing that much thickness. The original manufacturers head thickness is shown on the "U" for the serial number of the tank from the National Board in Columbus, Ohio. If there was a corrosion allowance in the design, that amount is shown also. This is important to know for down rating the MAWP, scrapping or safely using.
Since moisture laying in the bottom of a tank is the most common point of failure when it rusts through I have often wondered why the manufacturers don't galvanize the interior? Is there some reason that wouldn't be viable other than the few dollars of cost? It is a given no matter how much or how often you drain the tank in such an oxygen rich environment (ten atmospheres or so), the fact moisture will always be present and that it takes so little to start and continue the oxidation process that this would be a problem that should be solved. Especially so since most drains have a welded in boss that is actually slightly higher than the bottom of the tank creating a reservoir of constant water. Nice project. Take care. Doug
The interior might BE galvanized, how would we know? But, whatever the manufacurer did, the tank seems fine after 30+ years, so it was... good enough.
Welded tank seams would have to be complete, and clean on the inside of the tank,
before galvanizing, though.
I like this idea. I'd make a few minor tweaks(Mostly being more careful about the air purge as others mentioned), but nothing really different.
Love this idea. Very good about the 'pressure washers can go up to stupid high values, so be carefull' warning.. I can easly imagine someone just holding down the trigger and hydro-forming instead of hydro-testing their tank.. :)
If the working pressure in a tank is 175 psi, you figure out how many square inches of tank surface you have and multiply it by 175. This is how manty thousands of pounds of explosive pressure you have waiting. That's why some call portable air tanks "Air Bombs". If you pressure test get all of the air out. Keith should have had a helper to tilt the tank to get more air out. I was trained at Quincy Company over 40 years ago.
Quincy Illinois,or one of their other plants?
My uncle worked at the Ill plant.
The instructions on French aerosol cans used to refer to the can as "la bombe" but in the last couple of decades this has been changed to "l'aerosol".
Good job. I bought an old Manchester pressure water tank (120 gal) for $70. I’m in the process of trying to clean the inside. But should I do this pressure test first?
Either way? How would I clean the inside? I’ve seen fancy rollers (pitch) that roll abrasive material inside while slowly tilting (roll) to get the ends. But this beast is big. I’d rather find an easier way to scrub the inside.
Thinking of Evap-o-rust followed by a wet sandblaster with my pressure washer. Then apply a rust stopper coating inside followed by epoxy resin. I just don’t know. You look like you know what you’re doing (except when you said “solid water 😬), so I’m asking you for advice. The tank is 40 years old and was being used as an air reservoir when I bought it. It has a lot of ports on it and a handle on top. Also has a drain valve underneath.
Thanks for your attention. I like the quality of your work.
(Max pressure inside will be 150 psi. It’s rated for 200).
Paul.