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Drill & tap compressor tank?
"DaveC" wrote in message news.net... I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? I'd be totally surprised if your tank has the wall thickness you speak of. They typically are thinner, especially if it's rated for 125 PSI. If it has, it would be adequate for a 1/4" pipe thread, but marginally. Best policy is to weld in a bushing, assuming you have the capability. Are there rules to follow for such stuff? Pressure vessels are generally built to the pressure vessel code, so, yes, there are rules. Ernie is our chief cook and bottle washer where welding is concerned. With luck, he'll chime in. Is there a better n.g. to ask this question in? The one he frequents most, which I don't recall. I think it's scientific welding and joining, or some such. Others will probably provide the proper group for you. Harold |
On Thu, 25 Aug 2005 20:24:29 -0700, DaveC wrote:
I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? Thanks, It is nowhere near 1/4" thick. Probably less than 1/8". I don't recommend welding on it. But if you're going to anyway, why not just weld on a coupling that is already threaded? |
"DaveC" wrote in message news.net... I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? Thanks, -- Please, no "Go Google this" replies. I wouldn't ask a question here if I hadn't done that already. DaveC Dave Since this is a drain, and you are concerned about the integrity, maybe you'd be less concerned with a 1/8th pipe valve, or petcock. But, if the tank pressure never gets higher than 125 psi, the force on 1/2 inch diameter area is only about 25 pounds. Besides, the valve is on the bottom so there is minimal probability of any failure injuring anyone. Jerry |
"Harold and Susan Vordos" wrote: (clip) Others will probably provide the proper group for you. ^^^^^^^^^^^^^^^^ It's sci.engr.joining.welding Ernie follows this group pretty closely as well--he will probably read your post. |
On Thu, 25 Aug 2005 20:24:29 -0700, DaveC wrote:
I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? It won't be thick enough to tap. Have a plumbing fitting welded or brazed in. I'd braze it. That's what I did on my tank. Plumbing fittings are often cast iron which can be welded to steel -- but brazing is a lot easier, would have ample strength and is less likely to have pinhole leaks or cracks. Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? There are rules for damned near everything, but if it's for your own use I wouldn't worry about it. As Jerry noted, there isn't much hydrostatic force on a small fitting like that at 125 PSI. |
"Andy Asberry" wrote in message
... | On Thu, 25 Aug 2005 20:24:29 -0700, DaveC wrote: | | I've got an old 20 gal (?) compressor tank in which I want to install a | drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to | 125 psi. | | Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" | welded to it that I can drill & tap? | | Are there rules to follow for such stuff? Is there a better n.g. to ask this | question in? | | Thanks, | | It is nowhere near 1/4" thick. Probably less than 1/8". I don't | recommend welding on it. But if you're going to anyway, why not just | weld on a coupling that is already threaded? If the coupling stuck up inside the tank, there'd be a puddle that the drain could not get to. I wonder how well a flange would work brazed to the tank. Drill the hole, shape the flange to match very closely, then braze in place. The low heat of brazing will not affect the heat treatment of the tank wall that much. The flange ought not to be small, though. Weld a coupling to the flange before brazing and connect that to the drain valve. Does this sound safe? |
"carl mciver" wrote in message k.net... snip---- The low heat of brazing will not affect the heat treatment of the tank wall that much. Not true, Carl. Anything above 700 F will change any heat treat present in carbon steel for the worse, but I'm not convinced tanks are heat treated, so it's a non-issue. Brazing, even silver brazing, occurs at a temperature over 1,000 F. Harold coupling to the flange before brazing and connect that to the drain valve. Does this sound safe? |
"DaveC" wrote in message news.net... I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? I got a great find last year in a nice two-stage pump that only needed the valves re-seated to make it cherry again. I was also given a beautiful, hot-dip galvanized upright propane tank of 100gal capacity. Hmmmm..... I think I see a picture here. I didn't want to compromise the tank's integrity because I'm NOT a good weldor. So, I looked at things from a Rube Goldberg point of view. Here we fill port, output port, and gauge port. The fill and output were both 1" NPT bosses in good shape. The gauge port was a huge 2-1/4" machined flange with the gauge bolted down onto a gasket. Ok... fill will be fill; just screw in a check valve. Output was output; natch. Took off the gauge and extracted the float assembly. Machined a manifold that sat where the gauge used to. In the manifold is a: Pressure relief port (tested... it does keep ahead of the pump), a pressure gauge port, and... and... a dip-tube drain. It's just a copper pipe that kisses the bottom of the tank, and a petcock valve to open it to ambient pressure. Air pressure pushes the water up the tube. I welded the pump base to the top flange and the feet to the bottom flange -- never once touched a torch to the tank itself. Since I'm not a weldor, I feel safer, and I've got a perfectly servicable upright that has a drain valve I can actually reach without aggravating my knees. LLoyd |
"DaveC" wrote in message news.net... I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? Thanks, don't all compressors already have a drain, unless this is a homebrew job? |
"DaveC" wrote in message news.net... This sounds like a very creative idea, but I'm having difficulty picturing what your set-up is. (A compressor with a "float assembly"? Water actually accumulates enough to require a float?) It was a propane tank in real life. It had a float-actuated gauge. The gauge port was BIG, so it was a nice place to combine some functions. I've got 2 ports on this tank: input (small boss fitted with 1/4 copper tube connecting to compressor output), and output (large (2-inch?) threaded boss with 1/4ntp threaded adapter (plug) connecting to 1/4 pipe with tees for gauge and quick disconnect hose fitting). Hmm... I could adapt the input to also act as output, and put the dip-tube drain on the large boss. How, exactly, is a dip-tube drain constructed? How do you fit a tube internally and connect that to the backside of a 1/4ntp (or such) output? The manifold had two holes straight through into the top of the tank: one for the relief valve and one for the new pressure gauge. It had a THIRD hole that had a petcock on the outside, and a copper compression fitting on the inside to accept the dip tube. LLoyd |
"DaveC" wrote in message news.net... Thus spake DaveC: In the manifold is a: Pressure relief port (tested... it does keep ahead of the pump) What's the purpose of a pressure relief port? Is this an "open at x psi" valve to keep pressure below the tank's limit? But this is what an electrical pressure switch does. Dave, pressure switches weld shut in storms, or with age, or with mud-dauber nests inside them. EVERY compressor must have a pop-off valve to protect the tank from over-pressure. LLoyd |
In article .net,
DaveC wrote: Thus spake Charles Spitzer: don't all compressors already have a drain, unless this is a homebrew job? no, this one doesn't. Craftsman brand, old. That sounds very strange. I have an old Craftsman -- horizontal tank, belt-driven pump, two wheels at one end and a handle at the other. Between the wheels, on the underside, is the drain valve. It was rather small -- perhaps 1/4" NPT thread. It had a T-handled valve, which was hollow for the water to flow out. It was rather prone to jam, so I replaced it with one with a knurled knob on the end, and a silicone rubber-gasketed seat on a wider portion on the inside. That one remains controllable with just my fingers. If there were room, I would replace it with a timer controlled solenoid valve, but there is not on this one. You might consider looking up the parts list for your model on Sears' website, to see whether it lists a drain valve as part of what it should have. I could imagine taking the output fitting and replacing it with a concentric fitting, with the inner part being a dip tube to drain from near the bottom, and the outer part passing air to the regulator. Enjoy, DoN. -- Email: | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- |
"DaveC" wrote in message news.net... I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? Thanks, -- Please, no "Go Google this" replies. I wouldn't ask a question here if I hadn't done that already. DaveC This is an invalid return address Please reply in the news group Are there rules for such stuff? I would hope there are, in your country. If you don't know the answer without asking don't mess with air or gas filled pressure systems. There are some very scary answers to this question. |
DaveC wrote:
So I guess without some custom "manifold" or such, there's no way to fit a dip tube, internally. All I have is threaded holes in the tank for 1/4 inch input, and 3/8 inch output ... I assume that your 3/8 threaded hole is NPT. In which case, use a npt-compression adapter/union, 3/8 NPT to 1/4 (OD) compression. Such as McMaster-Carr #50915K316: http://www.mcmaster.com/ But also generally hardware-store available. Drill out the adapter to 1/4" to allow the tube to pass through it. The fitting has plenty enough "meat" to do this, but as-made it stops the tube for ease of assembly. Screw the adapter to the tank, pass the tube through it, tighten the compression sleeve/nut, add a compression-fitting valve to the tube. If you file a notch on the in-tank end of the tube, you can lower it all the way to the bottom and still have an opening for the water. If you first fit a 3/8 NPT tee to the tank, with the straight-through vertical, you can take your tank output from the horizontal leg, while fitting the dip tube adapter to the top. The dip tube will be co-axial with part of the output path, but with enough room for air flow. HTH, Bob |
In article .net,
DaveC wrote: I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? Thanks, You could try avoiding modifying the tank altogether. Get a pipe cross, mount the tank above so the pipe has to go up to get into the tank, then have a six to eight inch (assuming it's 3/4 or 1"--longer for thinner pipes unless you don't mind draining more often) leg of pipe go out the bottom of the cross to collect water and gunk. Stick a drain at the bottom of that pipe. Then use the remaining two sides of the cross for inlet and outlet. Not pretty or very mobile, but works OK. -- B.B. --I am not a goat! thegoat4 at airmail dot net http://web2.airmail.net/thegoat4/ |
DaveC wrote:
I've got an old 20 gal (?) compressor tank in which I want to install a drain. I'm guessing it to be 1/4-inch (6.3 mm?) thick steel. Tank is rated to 125 psi. Can I drill and tap this for 1/4 or 3/8-inch pipe? Or should i get a "plug" welded to it that I can drill & tap? Are there rules to follow for such stuff? Is there a better n.g. to ask this question in? A welded iron half-coupling is the correct way to go. Do it yourself if you can. Your tank isn't worth what a shop would have to charge--about $80 or their one hour minimum. good luck, Boat_dreams |
A 'Pressure relief port or valve' is a redundant safety feature. (Required
by most codes for any pressure vessel.) Electrical pressure switches do fail. -- $.02 Chipper Wood useoursatyahoodotcom "DaveC" wrote in message news.net... Thus spake DaveC: In the manifold is a: Pressure relief port (tested... it does keep ahead of the pump) What's the purpose of a pressure relief port? Is this an "open at x psi" valve to keep pressure below the tank's limit? But this is what an electrical pressure switch does. What's a relief port? -- Please, no "Go Google this" replies. I wouldn't ask a question here if I hadn't done that already. DaveC This is an invalid return address Please reply in the news group ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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