Old compressor tank - hydro or not?

[lakeroadster]

Other issues i have yet to be satisfied about are claims that asme tanks don't usually rupture when they fail from corrosion, they just spring leaks due to "superior ductility" etc etc.

Oh, they'll rupture.

Yes, they are made from mild steel which is in fact ductile... but if a pinhole turns into a crack and it propagates... it usually ends badly when the tank contains a compressed gas. A lot of energy being released very quickly.

 

[Fixin'Stuff]

Even little tanks can make a big boom. Jump to 1:30:

 

[LS6 Tommy]

Your tank is thin to be 120 Gal. It's got an ASME "U" stamp so that says it met the boiler and pressure vessel code rules and satisfied an inspector when it was made.

Per the interweb:

"The U Code Symbol on a vessel is used to confirm that the stamped item is in conformance to the latest edition of the Code and that the pressure vessel has been designed and manufactured in accordance with ASME."

I looked into hydro-testing tanks quite a bit for the same reasons you are. There are places that do hydro tests on all kinds of stuff as you might imagine.

What all the youtube grease-gun testers miss is checking for yield.

The "real" places submerge the tank in a larger tank and both fill it with water and submerge it in water. They pressurize the tank under test AND very accurately measure the displaced water in the outer tank. When the test tank gets pressurized, it swells. The testers make sure that it returns to the pre-test non-pressurized volume. If there is any displaced volume once the tank under test is de-pressurized, the assumption is the tank yielded and failed the test.

I've brought all that up a few times before in threads where grease guns and pressure washers were recommended. I was dismissed as a "Safety Nazi"...

Tommy

 

[Lelandwelds]

The "real" places submerge the tank in a larger tank and both fill it with water and submerge it in water. They pressurize the tank under test AND very accurately measure the displaced water in the outer tank. When the test tank gets pressurized, it swells. The testers make sure that it returns to the pre-test non-pressurized volume. If there is any displaced volume once the tank under test is de-pressurized, the assumption is the tank yielded and failed the test.

I believe you are confusing DOT cylinders with pressure vessels. Different regulatory rules.

The end user of a "U" stamped ASME Section VIII Div. 1 pressure vessel should never pressurize the vessel above its rated MAWP... never.

Manufacturer's and Repair organizations go through strict audits in order to be qualified to build, repair and alter pressure vessels. They have mandatory 3rd party inspection to ensure compliance. They are authorized, under certain rules and regulations, to test a vessel above it's rated capacity. This is typically done during the vessels hydrostatic test before the ASME "U" Stamp is applied, or during a vessel alteration.

An in-service hydrostatic test is performed by filling a vessel with water and pressurizing it to or below the vessels MAWP. You don't do the test under water. You are checking the vessel for leaks. I have seen vessels where pin hole leaks didn't become apparent for hours... as was evident by water on the outside of the vessel. Extreme care should be exercised to ensure air is not trapped in the vessel during this test. This can end in catastrophic results and is why untrained individuals performing these tests can be very dangerous.

Sometimes a manufacturer will perform a proof test. A proof test is when the vessel is pressurized until it fails. This is done under controlled conditions by professionals, according to written approved procedure. Proof tests are used when a design is beyond the scope of the ASME code... something where there are no calculations applicable to the new design.



The thickness stamped on the nameplate is the minimum required thickness.... not the thickness of the tank when it was new. Newer nameplates do not show this data.

Accurate but actually mixing DOT, pressure vessels, and firearms practices. Thats destructive testing not proofing. Proofing is hitting a target pressure without the dramatic failure.

I
I did get a small amount of rust out of the tank by standing on end with my engine hoist. Probably a quart? (guess)




What would you do?

A quart of dry powder rust is a fairly large amount. Buy an inexpensive USB camera and look inside. Can this one be tumbled with a media? Build a version of drag race transmission blanket if you absolutely must. I Instead of 175 PSI tank pressure, use it as a dry tank and operate it at 90 PSI line pressure.

Oh, they'll rupture.

Yes, they are made from mild steel which is in fact ductile... but if a pinhole turns into a crack and it propagates... it usually ends badly when the tank contains a compressed gas. A lot of energy being released very quickly.

Well, that does sum up the problem.

Its not a pinhole. It is a line of corrosion weakened steel for horizontal tanks. (Bomb like failure) Vertical tanks have nearly the entire bottom fail. (Rocket like failure.) It is rare but I know of three failures local ( well, local for Texas) to me. One was fatal.

 

[LS6 Tommy]

I have been to hydrotests of ASME recerts of compressor receivers. They absolutely are submerged in water.

Tommy

 

[86turbodsl]

I have been to hydrotests of ASME recerts of compressor receivers. They absolutely are submerged in water.

Tommy

Jeez, with the kind of fear and death talked about in this thread, i'm amazed anyone will dare to have an air compressor.

It can't be that common to have a catastrophic failure. I haven't ever met or talked to anyone who had one.

A quick scan of the mlive.com (website search for all michigan newspapers) shows ZERO stories about tank explosions. It goes back quite a few years.

Perhaps the thread title drew mainly those with tank explosion experience?

Not trying to belittle anyone here, and i certainly fully understand the stored energy of the tank, but i don't think it's that common.

What i was really looking for was some data points on other's experiences and how likely a problem would be.

Consensus in this thread seems to indicate put my coffee down, back away slowly from the tank and call the bomb squad (said in jest).



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[Mooky]

Check your private messages, I can send the ASME / API "Fitness For Service" code to your email.

As an engineer, the calculations will be straightforward.

Mooky:
MSME
API 570 / National Board Inspector
AWS CWI

 

[86turbodsl]

Check your private messages, I can send the ASME / API "Fitness For Service" code to your email.

As an engineer, the calculations will be straightforward.

Mooky:
MSME
API 570 / National Board Inspector
AWS CWI

Replied. Thanks.

Also thought if this tank passes the required testing, perhaps stand on end and convert to vertical? The material thicknesses closely match a modern Hanson tank i just looked up. 250psi WP, 120 gal vertical. The bottom would then be new material and the old bottom not be exposed to any standing water. I also planned to add a solenoid auto drain so even that would be minimal. Probably the main issue will be the humid air contained in the tank. Hoping a coating will mitigate that.

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[lakeroadster]

Jeez, with the kind of fear and death talked about in this thread, i'm amazed anyone will dare to have an air compressor.

Folks are looking out for you and your families best interest.

There's some good data in this thread 86turbodsl in regard to testing... https://www.garagejournal.com/forum/showthread.php?t=343459&highlight=asme

 

[6768rogues]

A whole quart of rust scale-powder seems like a lot, maybe not??




NOW.........yer scare'in me....

Do you happen to have any pics of the damage you could share on here?

No pics. It was about 20 years ago. I remember when it happened and I saw the damage, and then after he passed away I found the old tank when cleaning up a scrap pile.

 

[86turbodsl]

Sweet. Got a quote to do ultrasonic checking of the bottom of the tank. $725. YIKES.
New 120 gallon tanks are about $650.



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[Lelandwelds]

Also thought if this tank passes the required testing, perhaps stand on end and convert to vertical? The bottom would then be new material and the old bottom not be exposed to any standing water. I also planned to add a solenoid auto drain so even that would be minimal. Probably the main issue will be the humid air contained in the tank. Hoping a coating will mitigate that.

All are excellent plans. I would add " operate at line pressure not tank pressure".

Jeez, with the kind of fear and death talked about in this thread, i'm amazed anyone will dare to have an air compressor.

It can't be that common to have a catastrophic failure. I haven't ever met or talked to anyone who had one.

A quick scan of the mlive.com (website search for all michigan newspapers) shows ZERO stories about tank explosions. It goes back quite a few years.

Perhaps the thread title drew mainly those with tank explosion experience?

Not trying to belittle anyone here, and i certainly fully understand the stored energy of the tank, but i don't think it's that common.

What i was really looking for was some data points on other's experiences and how likely a problem would be.

Consensus in this thread seems to indicate put my coffee down, back away slowly from the tank and call the bomb squad (said in jest).

Three in forty years of my experience. I know of more people who were literally struck by lightning.

The problem with newspapers is when someone screws up that bad, they make serious attempts to cover it up. The newspaper story said "industrial accident" for the one fatality. The other two did not make the paper and corporate was not informed and OSHA NEVER heard about it.

Duh.

Folks are looking out for you and your families best interest.

]

Nah, we just like to flame and pile on.

 

[86turbodsl]

All are excellent plans. I would add " operate at line pressure not tank pressure".



Three in forty years of my experience. I know of more people who were literally struck by lightning.

The problem with newspapers is when someone screws up that bad, they make serious attempts to cover it up. The newspaper story said "industrial accident" for the one fatality. The other two did not make the paper and corporate was not informed and OSHA NEVER heard about it.

Duh.



Nah, we just like to flame and pile on.

I had figured on operating at 150-160 psi, not 200. I need a little more than normal for the tire machine. Otherwise it would probably be 130.

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[Lelandwelds]

I had figured on operating at 150-160 psi, not 200. I need a little more than normal for the tire machine. Otherwise it would probably be 130.

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Typical is 175 PSI at tank and 90 PSI in the loop for small installations. The big guys will operate at as few PSI as possible for dramatic energy savings. I find the different strategies used oddly fascinating.

My dream system is variable pumping volume, variable storage volume, and variable pressure. It's way simpler than it sounds. A few check valves and ball valves added. A small single stage handles routine air needs. A larger two stage with additional storage operates only when an air hog is used.

I am hoping the new Eastwood scroll works as hyped. It would be the ticket. Or, its success inspires a bunch of competitors to announce models.

 

[sberry]

My dream system is variable pumping volume, variable storage volume, and variable pressure. It's way simpler than it sounds. A few check valves and ball valves added. A small single stage handles routine air needs. A larger two stage with additional storage operates only when an air hog is used.

This is the kind of thought Iwould have had earlier in my career. Today its more along the lines of a 2 stage pump and a regulator at the end to get to working pressure which may vary a bit with load and hose size/length.

 

[86turbodsl]

Typical is 175 PSI at tank and 90 PSI in the loop for small installations. The big guys will operate at as few PSI as possible for dramatic energy savings. I find the different strategies used oddly fascinating.

My dream system is variable pumping volume, variable storage volume, and variable pressure. It's way simpler than it sounds. A few check valves and ball valves added. A small single stage handles routine air needs. A larger two stage with additional storage operates only when an air hog is used.

I am hoping the new Eastwood scroll works as hyped. It would be the ticket. Or, its success inspires a bunch of competitors to announce models.

As i mentioned in my other thread where i showed my quincies, i'd like to do variable speed/vfd drive and monitor demand too. I'll set the pressure just high enough to get my tire machine to dismount tires. I think that's my only constraint here. I don't need high pressure for most of the tools.

I was intrigued enough by the Eastwood scroll announcement to look into HVAC compressors but my HVAC buddy told me that they don't have a high enough compression ratio to be useful. Darn...

 

[LS6 Tommy]

Jeez, with the kind of fear and death talked about in this thread, i'm amazed anyone will dare to have an air compressor.

It can't be that common to have a catastrophic failure. I haven't ever met or talked to anyone who had one.

A quick scan of the mlive.com (website search for all michigan newspapers) shows ZERO stories about tank explosions. It goes back quite a few years.

Perhaps the thread title drew mainly those with tank explosion experience?

Not trying to belittle anyone here, and i certainly fully understand the stored energy of the tank, but i don't think it's that common.

What i was really looking for was some data points on other's experiences and how likely a problem would be.

Consensus in this thread seems to indicate put my coffee down, back away slowly from the tank and call the bomb squad (said in jest).



Sent from my SM-N910T using Tapatalk

I never said anything along those lines. I just stated that I was dismissed as a
Safety Nazi for suggesting a DYI hydro test using a pressure washer or grease gun is not the best idea and that I have witnessed compressed air receivers get hydro'd for recertification and they were submerged in water.

Tommy

 

[86turbodsl]

Tommy,

I wasn't focused just on what you wrote. No worries man. We're good.

 

[Lelandwelds]

As i mentioned in my other thread where i showed my quincies, i'd like to do variable speed/vfd drive and monitor demand too. I'll set the pressure just high enough to get my tire machine to dismount tires. I think that's my only constraint here. I don't need high pressure for most of the tools.

I was intrigued enough by the Eastwood scroll announcement to look into HVAC compressors but my HVAC buddy told me that they don't have a high enough compression ratio to be useful. Darn...

I am less than thrilled about small VFD air compressors. If you slow enough to be interesting, it doesnt splash oil so good. If spin it enough to wake things up, it starts to get a bit noisy.

I would like soft start, though. Avoiding inrush current and frequent starts would be nice.

Monitoring demand is far beyond my abilities to inexpensively homebrew. Commercial offerings are freakishly expensive. When I want less, my needs are really minimal and extra storage would overwork my little guy. When I need more, I really need more of everything.

More, more, more!

 

[86turbodsl]

I am less than thrilled about small VFD air compressors. If you slow enough to be interesting, it doesnt splash oil so good. If spin it enough to wake things up, it starts to get a bit noisy.

I would like soft start, though. Avoiding inrush current and frequent starts would be nice.

Monitoring demand is far beyond my abilities to inexpensively homebrew. Commercial offerings are freakishly expensive. When I want less, my needs are really minimal and extra storage would overwork my little guy. When I need more, I really need more of everything.

More, more, more!

Compressors have a range of speeds. Just make sure you run between the range ends. For instance, my Quincy 325s are rated from 400 to 900 rpm. Set 400 at about 30Hz and run frequency up to whatever it needs for 900.

I do plan to use a 4-20ma transducer and one of my plcs for monitoring so i might be overcomplicating it, but i enjoy these types of engineering excercises.

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[LS6 Tommy]

Tommy,

I wasn't focused just on what you wrote. No worries man. We're good.

Same here!

Tommy

 

[metlmunchr]

I was intrigued enough by the Eastwood scroll announcement to look into HVAC compressors but my HVAC buddy told me that they don't have a high enough compression ratio to be useful.

Standard operating pressures for R410a air conditioning systems is 420 psi on the high side and 130 psi on the low side. Differential across the compressor would be 290 psi at those conditions.

The real problem with any home brewed scroll or screw compressor would be removal of oil from the compressed air. IIRC, Eastwood has moved the release date back 2 or possibly 3 times on their comparatively cheap scroll. I suspect that's due to resolving oil removal problems while maintaining the price point.

 

[86turbodsl]

Standard operating pressures for R410a air conditioning systems is 420 psi on the high side and 130 psi on the low side. Differential across the compressor would be 290 psi at those conditions.

The real problem with any home brewed scroll or screw compressor would be removal of oil from the compressed air. IIRC, Eastwood has moved the release date back 2 or possibly 3 times on their comparatively cheap scroll. I suspect that's due to resolving oil removal problems while maintaining the price point.

Right, so a cr of about 3. Not useful. We will see what Eastwood comes up with.

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[dkmc]

I do plan to use a 4-20ma transducer and one of my plcs for monitoring so i might be overcomplicating it, but i enjoy these types of engineering excercises.

Now you've got my attention....
A nice 6 or 7" touch screen HMI on the wall to monitor and manually adjust speed/pressure would be nice as well!

 

[Lelandwelds]

This is the kind of thought Iwould have had earlier in my career. Today its more along the lines of a 2 stage pump and a regulator at the end to get to working pressure which may vary a bit with load and hose size/length.

I just dont know how to interpret this one comment.

Set 400 at about 30Hz and run frequency up to whatever it needs for 900.

I do plan to use a 4-20ma transducer and one of my plcs for monitoring so i might be overcomplicating it, but i enjoy these types of engineering excercises.

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Now you've got my attention....
A nice 6 or 7" touch screen HMI on the wall to monitor and manually adjust speed/pressure would be nice as well!

Ok, you lost me. Please post more. My google fu needs the work out. The only transducers Ive seen are on ultrasonic cleaners. I hope Arduino works instead of plcs.

A googling we go... hi ho...

I got interested in compressed air systems about fifteen years ago. One of my customers modernized their plant and saved pretty close to $100k the first year in electrical costs alone. If they could have put a firm, true dollar figure on maintenance costs and production slowdown costs, I think some people would have gotten fat bonuses or pink slips. It was scary for them and fascinating for me. Hooked ever since.

 

[Tracs]

Sweet. Got a quote to do ultrasonic checking of the bottom of the tank. $725. YIKES.
New 120 gallon tanks are about $650.



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A lot of great technical info in this thread. I was just about to ask the cost for pressure/ultrasonic check of the tank. I had a suspicion that it would cost more than a new tank.

 

[86turbodsl]

A lot of great technical info in this thread. I was just about to ask the cost for pressure/ultrasonic check of the tank. I had a suspicion that it would cost more than a new tank.

Yeah, the guy didn't even bat an eye at quoting me for a little tiny tank either. I wonder how many he does... I've decided not to UST the tank. It will either pass the proof test or it wont.

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[86turbodsl]

I just dont know how to interpret this one comment.





Ok, you lost me. Please post more. My google fu needs the work out. The only transducers Ive seen are on ultrasonic cleaners. I hope Arduino works instead of plcs.

A googling we go... hi ho...

I got interested in compressed air systems about fifteen years ago. One of my customers modernized their plant and saved pretty close to $100k the first year in electrical costs alone. If they could have put a firm, true dollar figure on maintenance costs and production slowdown costs, I think some people would have gotten fat bonuses or pink slips. It was scary for them and fascinating for me. Hooked ever since.

Ok, so i'm into Automation Direct PLCs. I have a DL06 in my home for HVAC control and an assortment of DL205's for other various projects. I'm setting one up in the shop right now to control the lights and security. One of the features in these plcs is PID control of a process. So i plumb a pressure transducer into the tank, with an analog output such as 0-10V or 4-20mA. Input into an analog card in the plc, and monitor the tank pressure. Using that value, i can program the plc to match the tank pressure by varying the output speed of the VFD. Assuming i get a VFD with the correct input of course. Since i plan to use both of my quincy 325s to replace an old 10hp curtis, i can set them to come on alternately to spread the load, and/or vary the rpm from a low of 400 rpm to a high of 900. If the demand exceeds one, i can bring the other online at that point. Energy savings should be pretty good over the old 10hp + phase converter to run it.

I don't know you could do this with an arduino, i've never played with those.

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[sberry]

What it means is that when I was 20 I had to try to put every fitting they ever invented in, every idea I saw somewhere I thought I needed, every pipe was 2 sizes bigger than it needed to be.
Today I try to work on design fundamentals vs more fittings, try to be somewhat simple and typical vs thinking I am really inventing something, follow alone with the code over "making it better" at every turn.
It doesn't mean I wont fix it or take care of it but I tend to take the factory unit as it was designed, plug it in, hook the hose to it and a regulator on the other end and every time I read about an auto drain fuk up I walk over to the comps and kick the drain valve open a blast which is plumed to a hose thru the wall.
I had it shut down to fix the motor, while I was at it changed the oil.
There was a thread a while back about a failed auto drain. Instead of getting rid of the pos the guy started adding several redundant systems in case it happened again. As I recall, a light setup and some kind of control, timers, new drain and some other **** that could have been solved with a ball valve.

 

[sberry]

Energy savings should be pretty good over the old 10hp + phase converter to run it.

How much is it running?

 

[dkmc]

I just bought a UT gauge on EBAY for $118. It'll either work or it will be a POS. We'll see.... Easy enough to verify the accuracy I think. I have plenty of samples of various metal thicknesses around the shop. If it checks out, I'll run a grid pattern on the tanks I need to test. There are 4 of them, all vertical. And I'm directly replacing 2 horizontal tanks that have pin holes right now. Never kept up on draining them. The replacements will have auto drains. The 4 replacements all are ASME stamped.
I can't complain, the 2 old tanks have served well for 30+ years at this point.

Yeah, the guy didn't even bat an eye at quoting me for a little tiny tank either. I wonder how many he does... I've decided not to UST the tank. It will either pass the proof test or it wont.

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[86turbodsl]

How much is it running?

I couldn't tell you other than the phase converter is quite large and gets turned on whenever i need to use any 3 phase so the move to VFDs with out RPC is implicitly understood to be more efficient.

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[Strouty]

I just bought a UT gauge on EBAY for $118. It'll either work or it will be a POS. We'll see.... Easy enough to verify the accuracy I think. I have plenty of samples of various metal thicknesses around the shop. If it checks out, I'll run a grid pattern on the tanks I need to test. There are 4 of them, all vertical. And I'm directly replacing 2 horizontal tanks that have pin holes right now. Never kept up on draining them. The replacements will have auto drains. The 4 replacements all are ASME stamped.
I can't complain, the 2 old tanks have served well for 30+ years at this point.

I will be curious to see how well it works. I needed the certification, so mine was a bit more expensive than that.

Auto drains are definitely the way to go, most people forget about draining compressors.

 

[lakeroadster]

Auto drains are definitely the way to go, most people forget about draining compressors.

Why? Do theses same folks forget to turn the lights off in the shop at the end of the day?

It's just a matter of course... put tools away, blow off the work areas with air, sweep the floor, turn the compressor power off, open the drain valve, close the drain valve, close the overhead doors, pull down the shades, turn off the lights, yadda, yadda, yadda.

I just drain the moisture once a day, when I am using my compressor. Save the air for another day.

A simple street elbow, piece of pipe and a ball valve does the trick.

I built a puke tank for mine using a Folgers can and some kitty litter to capture the rusty water.....

A flap cut in the lid, and a shop rag between the lid and can, allows the pressure to escape / vent.

easy peazy.

 

[Strouty]

You need to remember, most people are too busy to do the little things, of course the little things are what really matter.

 

[lakeroadster]

You need to remember, most people are too busy to do the little things, of course the little things are what really matter.

Too busy... that's just an excuse. This takes 15 seconds.

Automatic stuff breaks eventually...

 

[86turbodsl]

Too busy... that's just an excuse. This takes 15 seconds.

Automatic stuff breaks eventually...

And memories break too. It's called age.

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[dkmc]

Too busy... that's just an excuse. This takes 15 seconds.
Automatic stuff breaks eventually...

I get about 1/2 cup out of my one 35 gallon tank.....per month if I remember to open the drain valve. Which means if I did it each day, I might get 3 drops.
Probably why that tank lasted 30 years before the pinhole's on the bottom showed up.
Incidentally, that tank is a horizontal home made one, made from a 100lb propane tank that was a rebuilt unit. It didn't have propane in it, and has never smelled like propane.
It has legs welded to it, black iron fittings welded to it for air inlet and outlet, and a platform for the motor and Quincy 210 pump welded on top of it (lays horizontal).
Has worked well all these years. Would I do it again? Based on what I know about Air Receivers NOW.......NO I would not.

So anyway, it's not worth draining it every day. And the compressor is in the back room which I sometimes don't venture into for several days. (The contactor is in the main shop area, so I don't have to go all the way out there to turn it on or off)

The new cheap Chinese auto drain valves sold on EBAY for $25-50 seem to be quite reliable. They have built in strainers to protect the seats from dirt and damage. I'll check them to make sure they work a few times a year, and when I change the oil once a year. I think they'll be fine.

 

[Strouty]

Propane doesn't smell, the additive does.

 

[dkmc]

Propane doesn't smell, the additive does.

Whatever.......