Repairing compressor tank - possible?

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So about 2 years ago I got a really nice buy on a OLD 80 gallon upright tank with a 5hp/19 CFM compressor for $340.  I changed the oil and airfilter, switched the pressure switch to 125psi, built an air line (with the help of forum postings here), and have been enjoying it ever since.I have a manual release set up on the bottom drain valve.  I keep the tank pressurized and manually switch off the valve to the airline when I am not using it.  Through some very minor tank leakage that used to mean the tank would switch on and repressurize every 4-5 days.Well, yesterday I was working in the garage and the compressor fired up - the second time I had heard it that afternoon.  It's kept in a storage closet with the hot water heaters behind a closed door.  After the motor cut off, I hear a loud hissing sound at the bottom of the tank.  Hmm, I thought, I must have left the bottom release valve open.  Nope, it was closed.  I reached back behind the valve and felt air coming out - from the tank!  I put a mirror back there and saw a 2mm size hole!  There is no exterior rust.I dread the answer that I think I might get - that the bottom must be rusted out and that I will have to replace the tank.  Any way to at least attempt to patch this?  what about drilling out the hole and exploring the damage?  As you can imagine, the unit is 500+ pounds and mounted in the concrete floor on blocks.  It's gonna be a pain to do anything with.  I appreciate your thoughts....
Reply:You say you changed the pressure switch to 125psi...what was it originally?As far as tank repair, not a snowballs chance in hell. Scrap it and buy a new one.
Reply:Take tank, cut it up for scrap, go buy a new compressor.  Its just a ticking time bomb waiting to go off at this point.Lincoln 300 Vantage 2008300 Commander 1999SA250 1999SA200 1968Miller Syncrowave 200XMT350MPA/S-52E/xr-15Xtreme 12vs Millermatic 251 w/30A  Millermatic 251 Dialarc 250 Hypertherm 1250 GEKA & Bantom Ironwokers
Reply:I reallize this goes against all advise. Clean the hole and use JB Weld. Push it in with your finger. Let it cure for 24 hours. Fire it up and see if it leaks. Did it to mine with no problems holds 125 lbs.
Reply:dude , it will leave the ground , pull anchors , destroy property and possibly killl sumone........im a witness and there's another member on this site whom recently was hospitalized by this......b care        thermal arc 252i  -  millermatic 350P -   miller XMT, cp300ts, 30a 22a feeders, buttload of other millers, handfull of lincolns, couple of esabs  -   Hypertherm 1250 G3
Reply:See this thread, then decide...http://weldingweb.com/vbb/showthread.php?t=48232
Reply:Take my word for it, scrap it!!!                                    MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Wow.  That thread sounds kind of like me...or what could have been.Guess I'll scrap it.  Thanks for the heads up.  BTW I swapped a 175psi valve for a 125.
Reply:Dont scrap it, theres still a lot of things that you can do with it. I can speak from expierence when I say they make great BBQs Good move on not attempting to fix it. The hole on the outside is caused by rust on the inside, it has rusted to the point of being paper thin and now its not even paper thin in spots. Theres really only one thing that you have to do, take it out of use. BBQs, Smokers, gongs, cut in half and make two fire pits, water table for use with a plasma hand torch, target practice, the list goes on. I wish I were closer, Id pick it up and give you more than scrap for it.[Account Abandoned 8/8/16 Please Do Not Attempt Contact Or Expect A Reply]. See you on YouTube! -ChuckE2009
Reply:Ditto with what Lanse said.  Be creative and make something else with the tank and you might be able to sell it to help defer costs of a replacement tank or compressor.
Reply:donate the tank to me, i would love a good bbq pit
Reply:Watch Craigslist for a compressor with a bad pump or motor, buy it and use your components. A lot of the cheap import 60 and 80 gallon tanks last way longer than the pumps. I bought an 80 gallon compressor tank...less than 5 years old for $50....I just plumbed it into my existing air system for extra capacity.Jim
Reply:When you find the new tank, I'd leave the compressor and tank separate.  You really don't want the nasty vibrations from the compressor on your pressure tank.  Bolt the compressor down firmly to a concrete pad.  Lightly bolt the tank so you don't introduce any more stress.Dynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:depressurize it and tap on the bottom of the tank with a pointy bit of metal and see if it punctures it.Doesnt your tank have a screw in bung somewhere for inspection?  I think even my cheap craftsman has a 2" screw in bung on the top of it.miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:Originally Posted by jdchmieldepressurize it and tap on the bottom of the tank with a pointy bit of metal and see if it punctures it..
Reply:then feel completely at ease that there was no recourse to taking it out of service.  I expect that he will poke holes all through it with a ballpeen hammer.  I dunno, I just figured it was obvious that some destructive testing to prove it was in bad shape was always worthwhile.miller syncrowave 250hobart handler 140home made 400 amp engine driven in progress...
Reply:I'd think yourself damn lucky, it didn't take you on an aerial tour of your workshop.Get a grip and bin it before it bins you
Reply:definate decomission as a preasure vessal. but that doesn't mean you can't use it for something else. like what has already be posted by lanse. be creative. Everyone does a BBQ. why not do a wheel barrow or dual planters, etc.There are no problems. There are only solutions. It's your duty to determine the right one.Hobart Handler 210Airco 225 Amp MSM Stinger
Reply:So how do you know when it's time to put a compressor tank out of service? Mine is about 20 years old now, although it is not used daily and the climate is dry here most of the year.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:Originally Posted by bigbSo how do you know when it's time to put a compressor tank out of service? Mine is about 20 years old now, although it is not used daily and the climate is dry here most of the year.
Reply:do you drain the water from the tank regularly?"Those who hammer their guns into plows will plow for those who do not."Thomas Jefferson."When the people fear their government, there is tyranny when the government fears the people, there is liberty."Thomas Jefferson.
Reply:Originally Posted by jgrinerdo you drain the water from the tank regularly?
Reply:Those tanks don't have any rust prevention inside, I doubt if it makes any difference if you drain them or not, to their longevity, there's always moisture in there. When I went thru the same situation a few years back, I couldn't find a replacement tank for less than a new compressor. Now I have a nice new 3 cyl 2 stage pump and motor taking up space.edit: They do seem to always rust out on the bottom tho, so my theory may be BS. Maybe the air should be taken out of the bottom to stop using the tank as a trap...Last edited by Jake98; 09-10-2011 at 08:53 AM.
Reply:The older my pancake compressor gets, the farther away I keep it when using it.  Paranoid........Yep!I would guess (and hope i'm right) that pin holes are more common than catastrophic failures.
Reply:Ok guys, thanks everyone for chiming in on this topic.So I have since learned quite a bit - thanks to your advice - and am currently shopping for a replacement.First place I called wanted $715 for a new 80gal tank with a top plate.  Ouch.Makes me want to just find a whole new compressor similarly sized.  There are plenty of good deals out there on CL.  Problem is, I would be right back where I started with a used compressor of unknown condition.  And when DOES one retire a tank anyway?  Fortunately it seems like when most tanks fail they do so as mine did with a small hole and not a catastrophic failure.Anyhow, my next question is this:  if I went with a new tank without a top plate, could I use my old top plate and weld it on the new tank?  Would welding to a new tank compromise the integrity of the tank?  OR...keep it separate, mounting the motor/pump on the floor next to the tank.  The second option would not be preferable since floor space is needed in my shop.I cleaned out a jobsite where the guy was a mechanic, and there were a couple aluminum air-brake tanks there. I figured 'there's my answer'. They had leaks too.. Bet you end up at Lowes. My 60 gal. with 6hp? was half of what I could get a tank for.. good luck.
Reply:Originally Posted by grohlAnyhow, my next question is this:  if I went with a new tank without a top plate, could I use my old top plate and weld it on the new tank?  Would welding to a new tank compromise the integrity of the tank? OR...keep it separate, mounting the motor/pump on the floor next to the tank. The second option would not be preferable since floor space is needed in my shop.
Reply:+1 to what Stick-man said. Either find one with a mounting plate or mount it separately.
Reply:mount your compressor solidly to the floor.  *BOLT* leg extensions on to the tank and set it over the compressor.  Same floorspace used.  No vibrations on the tankDynasty200DX w/coolmate1MM210MM VintageESAB miniarc161ltsLincoln AC225Victor O/A, Smith AW1ACutmaster 81IR 2475N7.5FPRage3Jancy USA1019" SBAEAD-200LE
Reply:Hi all, with a tank that size and cost for replacement, I'd cut the hole bigger to eliminate the pitting from rust that has broken through, and then weld the hole up.The crucial test would be to fill it full with water, eliminating ALL air, and plug it off and then do a hydraulic test to 1-1/2 times the working prssure....leave at this pressure for 1/2 an hour, checking for further leaks.The water, if''n the tank ruptures due to serious corrosion internally, will just spurt out of the rupture and with depressurisation no further damage can occur.....i.e. there can not be an explosion with water under pressure as long as all the air is expelled before plugging and pressurising with a hand pump.You'll also need a pressure gauge indicating at least 200 PSI to test your 125 PSI to 1-1/2 times that pressure.....which is 185 PSI.Boilers are tested this way.Water, being incompressible will only exert a static force while the pressure is contained, and rapidly dissipates with even the tiniest leak.If'n you get another leak, examine the new leak and if'n it looks lik it is bulging at that area, then 10:1 the inside is beyond repair.....only fit for a BBQ.BTW, there is a device selling on Ebay called a USB endoscope, selling for about $45.It plugs into and is powered by the USB port of your computer...(laptop for portability), and you can use it to look inside anything with a 1/4" hole and up to a metre deep.The unit consists of a black box with a flexible 1 metre (3 feet) length of cable which carries a small video camera and an LED light in the end.For the price you can see inside anything you can stick the thing into, even look at the back of your head to check on your hair loss....LOL, or see if'n you've got the wax out of your ears etc.For your air tank problem, you could just drill the leak out to 1/4" plus, and stick the endoscope cable into it and have a sticky beak round the inside of the tank...it's got a light too so you will be able to see the damage and also take a few photos to save on your computer for analysis later.They also do one of these devices for plumbers, and it has a small screen in the black box and is self contained and battery powered so you don't need to hook it up to a computer, but it also cost about $150 to $200 or so.Any of those big pressure vessels should be tested regularly, as they are poterntial bombs with air under pressure.....even the hobby type can be lethal too if'n they aren't drained regularly and are a bit old.BTW, I think the Myth Busters did a test on a 2 litre Coca Cola bottle and pumped it up to 150 PSI, making a water powered rocket in one of their TV series.One of the biggest problems with pressure vessels is the stress that happens when the metal casing flexes during the inflation and deflation cycles....which can lead to a sudden and catastrophic rupture form the metal fatigueing and cracking, much like when you bend a piece of steel strip back and forth to break it.Ian.
Reply:Horizontal smoker time!   Once you see the inside of that old tank, you will know why. On a difficulty level, pressure vessels are, more than a few steps, above amateur. City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny