uncledj Posted September 22, 2015 Share #1 Posted September 22, 2015 The propane tank on my motorhome is leaking where the float / gauge assembly threads in. I gave up on trying to get the gauge assembly to seal, (Aluminum) and tried cleaning the female threads on the tank, then putting a brass 1" plug in with a hardening pipe dope, and tightened the heck out of it, but it still leaks. The female threads on the tank are less than perfect, ....looking a bit chipped and burred. I'm to the point where I'm considering welding a pipe coupling to the tank to get a decent thread, but if I can "chase" the threads on the tank, I should be able to get a good seal, but a 1" tap must be a rare item, since I don't have one in the garage. (I have 1/8 up to 3/4) Anyhoo, a couple of turns with a good tap should do the trick. If anyone out there has one and is willing to lend it, lemme know. Of course I'll pay shipping both ways, and may include a little extra something with the return. Thanks for your attention. Link to comment Share on other sites More sharing options...
slowrollwv Posted September 22, 2015 Share #2 Posted September 22, 2015 My son gave me a large tap and dye set I will look. Link to comment Share on other sites More sharing options...
slowrollwv Posted September 22, 2015 Share #3 Posted September 22, 2015 Yes I have a 1"nc8 tap. Do you need the handle with it? send me your address in PM and I will get in the mail tomorrow. Link to comment Share on other sites More sharing options...
uncledj Posted September 23, 2015 Author Share #4 Posted September 23, 2015 Yes I have a 1"nc8 tap. Do you need the handle with it? send me your address in PM and I will get in the mail tomorrow. That's a big ol' tap, but it won't do it for me. The one I need should say 1" NPT, for National Pipe Thread. A pipe tap is tapered, to cut a tapered thread, which is why a pipe joint will get tight before it runs out of threads. The further you turn it in, the tighter it gets, which is why a pipe thread seals, and a straight thread won't. I REALLY appreciate the offer, but I need a pipe tap. Thanks a bunch for the offer. Link to comment Share on other sites More sharing options...
kevin-vic-b.c. Posted September 23, 2015 Share #5 Posted September 23, 2015 I add this to the things you should not do..... and welding it is even worse. Just a gas fitter talking. If you are doping it and tightening it as much as you indicate, my bet is that the threaded fitting has a crack in it.... likely caused by over tightening or physical impact damage. If you can hand thread a clean pipe fitting into it and it will not seal when you put a wrench on it it likely has bigger issues just being me Link to comment Share on other sites More sharing options...
Flyinfool Posted September 23, 2015 Share #6 Posted September 23, 2015 I got close, I have a 1" 11-1/2 NPS tap. Same thread as an NPT but straight instead of tapered. I agree with Kevin that a tap is unlikely to fix your problem. It is likely that when you "tightened the heck out of it" that you stretched the thread and made it to big, or cracked the fitting, a tap will only make it bigger yet. Welding a new fitting on to a cracked fitting will only make a bomb. Link to comment Share on other sites More sharing options...
uncledj Posted September 23, 2015 Author Share #7 Posted September 23, 2015 Kevin and Flyinfool. Thanks for the input, but it's one of those things ya gotta see to understand. The female fitting that's part of the tank has a shallow thread, seems to be a poor grade of steel, and only protrudes from the tank barely more than the depth of the weld. Maybe 3/8" (from memory) This doesn't give it much room to expand and crack. Next time I take it apart I take a closer look, but the leak is small enough that if I fill it halfway (10 gal) it'll run the fridge and the water heater for a couple of months. (Minimal use.....a couple of weekends) Point being, it'll hold the gas that long. Anyway, if I weld a 1 1/4 threaded coupling to the tank....heck, I may just cut the old fitting out and insert a coupling through the tank and weld it in, it would be a whole new, proper threaded port. Been a while since I've welded anything that'd have to hold pressure, but I'm sure I'll get by. I was just hoping to avoid going through that by trying cleaning up the thread first. Link to comment Share on other sites More sharing options...
billmac Posted September 23, 2015 Share #8 Posted September 23, 2015 would it not be easier to get as new tank. maybe it's the gauge that's bad? Link to comment Share on other sites More sharing options...
jonesy Posted September 23, 2015 Share #9 Posted September 23, 2015 I never mess with propane gas, I'd get new tank, gauge in a heart beat. Never took chances at all. Link to comment Share on other sites More sharing options...
jimmy99 Posted September 23, 2015 Share #10 Posted September 23, 2015 Get another propane tank. It's just not worth messing around with when you consider the risk vs reward. I haul bulk propane for a living and I would not bother messing around with this thing once the simple solutions you have tried had been done. Even a very small leak can be catastrophic. If you modify the tank, welding etc., where would you get it filled? The guy filling it should refuse as he will be held liable if there is a problem later. Also consider the age of the tank, they do have to be pressure tested and certified at certain intervals. You might be able to buy a new tank from a local propane distributor rather than the RV dealer, might save some $$ Jimmy Link to comment Share on other sites More sharing options...
uncledj Posted September 23, 2015 Author Share #11 Posted September 23, 2015 Thanks for all the input....I'll give it due consideration. But...back to my original question....Anybody have a 1" pipe tap I can borrow???.....lol.... Link to comment Share on other sites More sharing options...
Great White Posted September 24, 2015 Share #12 Posted September 24, 2015 (edited) Seriously, just spend 30 bucks and get a new tank....pressure vessels holding flammables are not a place for "making it work". Heck, even pressure vessels holding non flammables is not a place to muck about! I'm not trying to sound like your "dad" or talk down to you, it's just I've seen the end result of a "bodge gone bad" with pressure vessels several times.....definitely not a place to take a chance. Edited September 24, 2015 by Great White Link to comment Share on other sites More sharing options...
jimmy99 Posted September 24, 2015 Share #13 Posted September 24, 2015 Seriously, just spend 30 bucks and get a new tank....pressure vessels holding flammables are not a place for "making it work". Heck, even pressure vessels holding non flammables is not a place to muck about! I'm not trying to sound like your "dad" or talk down to you, it's just I've seen the end result of a "bodge gone bad" with pressure vessels several times.....definitely not a place to take a chance. This will be a larger tank with a float gauge etc and worth more than $30. I understand the desire to make it work over replacing it. If you can borrow the pipe tap - chase the threads and test the connection for leaks. If it still leaks it is likely done and a replacement tank is needed. You might consider taking it to a propane distributor (not your local gas station) as they probably have the NPT taps and might be able to repair your tank. Jimmy Link to comment Share on other sites More sharing options...
Ozlander Posted September 24, 2015 Share #14 Posted September 24, 2015 There's one on e-bay for $22 free shipping. Good enough for one job. Link to comment Share on other sites More sharing options...
Great White Posted September 24, 2015 Share #15 Posted September 24, 2015 This will be a larger tank with a float gauge etc and worth more than $30... Regardless, that doesn't negate the rest of my post. Link to comment Share on other sites More sharing options...
uncledj Posted September 24, 2015 Author Share #16 Posted September 24, 2015 I'll look for the tap on e-bay. At $22 I can't go wrong. Clean up the threads on the tank, maybe even run a die over the threads on the gauge assembly and give it a try. I've been looking at new tanks as well. A 20 gallon horizontal goes for between $500 and $700. A bit pricey. Thanks to everyone that responded. Link to comment Share on other sites More sharing options...
uncledj Posted September 24, 2015 Author Share #17 Posted September 24, 2015 Bought a used one on e-bay, $17.95 to my door. After I freshen up the threads, I'll pressurize it to ? 30 or 40 lbs less than the rating on the relief valve and let y'all know how it went. Before everyone goes haywire....I'll pressurize with CO2, so no worries. Assuming it works, I'll probably then pull a mild vacuum on the tank to get most of the CO2 out. Us Commercial / Industrial HVAC guys have access to all kinds of cool stuff. Just not 1" pipe taps. They're not the sort of thing I normally need. Link to comment Share on other sites More sharing options...
billmac Posted September 25, 2015 Share #18 Posted September 25, 2015 got a picture of this $500.00 tank Link to comment Share on other sites More sharing options...
uncledj Posted September 25, 2015 Author Share #19 Posted September 25, 2015 (edited) Going from memory, this looks like an exact match to the one I have now. It's a 16 gallon, but I'd swear I saw a 20 gallon stamp on the one I have, although the 16 gal may be a max fill level. Anyhoo, I think this is the one I'd need,....fittings the same, mounts the same. http://www.amazon.com/Manchester-14-40-ASME-Tank/dp/B00HTN3GSY/ref=sr_1_15?ie=UTF8&qid=1443170825&sr=8-15&keywords=horizontal+propane+tank This is the first one I looked at. It's only a 11 gal, but it looks to be the biggest one that Adventurer has that looks like mine. http://www.adventurerv.net/gas-tank-112-gal-p-8389.html Edited September 25, 2015 by uncledj Added link Link to comment Share on other sites More sharing options...
billmac Posted September 25, 2015 Share #20 Posted September 25, 2015 thought you were messing with a bottle tank. Link to comment Share on other sites More sharing options...
BlueSky Posted September 25, 2015 Share #21 Posted September 25, 2015 Have you tried teflon tape? Link to comment Share on other sites More sharing options...
Ozlander Posted September 25, 2015 Share #22 Posted September 25, 2015 Have you tried teflon tape? Then you would be guaranteed a leak. Link to comment Share on other sites More sharing options...
BlueSky Posted September 26, 2015 Share #23 Posted September 26, 2015 Then you would be guaranteed a leak. I used teflon tape to stop my TT gas bottles from leaking at the threaded joints, or was that my imagination?? Link to comment Share on other sites More sharing options...
uncledj Posted September 27, 2015 Author Share #24 Posted September 27, 2015 I've no problem with Teflon tape, but something tells me you're not supposed to use it on propane. I'll have to look into it. Link to comment Share on other sites More sharing options...
BlueSky Posted September 27, 2015 Share #25 Posted September 27, 2015 Teflon is inert and won't react with anything. It is good for up to 500 degrees F. The only applications it isn't allowed that I know of is at nuclear power plants. Gamma radiation will break it down and cause leaks. Link to comment Share on other sites More sharing options...
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