Go BottomDiesel fuel pipe joints
 | Mark L
Join Date: Posts: 1 
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2002-10-01 43151
Can anyone help me with this one...
I have installed a small bulk storage tank and assembled all the bits including sight guage and delivery hose. All seemed well. After a week or two a couple of the joints between the fittings started to seep. It's very slow but annoying (like less than a drop a day). I've tried tightening the joints but it doesn't work. It'll be a month or 2 before I will emnpy the tank enough to dismantle it. Can anyone suggest how to prevent the problem with or without emptying the tank. I'm an accomplished plumber but this one is really puzzling me.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2002-10-01 43153
My furnace oil tank has a shut off valve first thing out of the tank. Fuel tanks may be required to have a shut off. I had a fitting that seeped a bit after a new furnace was installed. It stopped when I tightened it a bit. If it hadn't stopped, I would have turned off the shut off and replaced the fitting. I don't think Teflon tape and similar things work for either compression or flanged fittings. At least with compression fittings, the threads just supply pressure to seat the flares and don't provide seals like on plumbing and hydraulic fittings. I imagine that there are a standard for what type fittings can be used in fuel lines, and I’d check codes.
If there's no shut off I don't know what I'd do other than wait until I could tip the tank up or pump it in another tank. It's not easy, but it’s maybe easier than the similar situation in which my father-in-law finds himself. The fuel delivery guy comes to his cottage and fills the tank and then says "You know we cant' fill tanks that aren't sitting on concrete pads anymore. FIL says '@#)$(*&$&* why didn't you tell me that before you filled it so I could have moved the tank around?'"
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 | Billy
Join Date: Oct 1999 Posts: 975 Southeast Oklahoma 
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2002-10-01 43154
Maybe you should try some kind of diesel proof joint compound?
Billy ....
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| MRETHICS
Join Date: Jul 2003 Posts: 190 Star City, Indiana
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2002-10-01 43159
Without disassembly of the joint, use the following solution.
Spray ether on the joint to get it as clean as possible.
Then, get bar of Ivory soap. Take the bar of soap, and rub it in the area of the leak. You can do this without takeing the connection apart. Rub hard and shove that soap into the crack where the pipe and the fitting meet. Do this completely around the entire jount.
This should work if repeated every few days untill the tank is empty. Then a more permanent solution, like say teflon tape, can be used.
A bar of parrifin wax will work just as well.
A slice of bread or two wraped around the fitting containing powdered (not granulated) sugar and then pressed in the joint with a hammer and piece of soft wood will also work.
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-10-02 43208
Ops, seems like my furnace oil line isn't relevant to a bulk fuel tank (It would take awhile to fill a fuel can). I guess I did use ordinary iron plumbing fittings to connect an in-line filter to a borrowed fuel pump.
This probably is a gravity flow tank, and the joint probably is between the tank and valve. Otherwise, I don't understand why joints downstream from the valve couldn't be disassembled. I've had similar problems when tightening tapered threads and needed to end up with a particular orientation such as a valve handle up. Sometimes one up is too loose and the next is too tight. Teflon tape worked for me. In the meantime, there are some interesting ideas here about temporarily sealing the joint.
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| Mark L
Join Date: Posts: 1
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2002-10-03 43274
Thanks everyone for your help. I am very impressed with the range of suggestions. The tanks does have a shut off valve but it has a threaded nipple joint then the valve so it leaks at the 2 joints before the shutoff. It was assembled with what we call PTFE tape (which I think is the same as Teflon tape). I discovered when I loosened the joints distal to the shutoff valve thatthe tape appears to act as a wick to the diesel and also appears to be degenrating (certainly doesn't look or fell ike it does when used in water pipes). I removed as much tape from the joints as possible and retightened them and it appears to be much better. I now have a bit of a problem re the alignment of the joints but can't see without using some sort of tape how I can improve this. Anyway I'll wait until I can lift the tank on the FEL and tip it then I'll try to work out how to solve the problem long term. Any suggestions on what to use to fix the alignment problem would be much appreciated. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-10-03 43284
I have had some success ending with valve handles up by varying the width of overlap and the position of tape wrap on the threads, but it does take fooling around. I tend to use liquid rather than tape sealant on hydraulic fittings, but I don't know how liquid hydraulic sealant would work with diesel fuel. At least with hydraulics, care should be taken that neither liquid nor tape is wrapped on the end of the male threads so that it may extend into the oil stream. ....
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| Mike C.
Join Date: Posts: 1
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2002-10-05 43396
I install fuel oil piping on boilers that use diesel and heavy oil. Fuel weeping from the joints is annoying. The condition of the pipe threads is the most important thing. There are many products available that claim to stop fuel leaks. However, I have found that by having good clean threads and then using locktite (blue)hydraulic thread sealant (on the male threads), wrapping a layer of teflon tape around that, and then a few more drops of hydraulic sealant will stop fuel (and steam) leaks. Compression and tapered threads do not use sealants.I can't imagine teflon tape decomposing since the half life of that stuff is say, 10,000 years. ....
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 | Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-10-05 43409
PTFE = polytetrafluroethylene = DuPont's Teflon
DuPont invented the process for the polymerization of tetrafluroethylene.
PTFE tends to wick if the joints is not tight. The Loctite is probably better or pipe dope. For a large tapered pipe fitting you need a lot of torque to get the pipe threads tight.
For external problems there is material available to cover the joint. I have a seep in a braised joint on my MF 65 fuel tank. I few years ago I cleaned the area and applied the 2 part solid epoxi. Has not leaked in 3 years. ....
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 | Art White
Join Date: Jan 2000 Posts: 6898 Waterville New York
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2002-10-05 43413
Peters, I wouldn't have a chance in what ever of saying that word much less what I think is spelling it right. Glad someone here is up for it. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-10-05 43417
I guess I should add that TPFE is one of most chemically stable polymers. For example extremely strong acids such as HF are kept in PTFE bottles. Polyethylene gas tanks are flurinated to reduce the release of volatiles from the tanks. ....
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| karmakanic
Join Date: Jul 2003 Posts: 5 NE Texas
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2002-10-11 43721
Hi Mark,
Concerning your alignment problem. I assume you're referring to the valve no longer being straight up and down, but it's tilted clockwise because you tightened the intake pipe beyond it's original position. I'm also assuming you're working with taper pipe threads.
(probably gonna be in trouble with all these assumptions, but here goes, my 1.5 cents worth.)
If that's the case the only true fix is to continue tightening a full turn to get your valve turned the way you want it. Taper pipe threads are designed with enough clearence between male and female to allow you to do this.
May take a cheater pipe on the old pipe wrench, but it should be do'able.
You can't back up, and you shouldn't use teflon tape or any other sealer to allow you to position the valve.
Taper pipe fittings seal by deforming the male and female threads to match each other as you tighten up. Once they've deformed, you have to always go forward to maintain the seal. This also means you have to tighten the heck out of them, especially in the larger sizes.
HTH,
Dave
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-10-12 43735
Thanks for the note Dave. I'll probably give up my use of tape on tapered threads to position valves. When I was a kid, I created enough nightmares for myself by breaking or stripping things so I now avoid what I think of Hercules maintenance, so use of tape was a natural for me. ....
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| Mark L
Join Date: Posts: 1
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2002-10-14 43816
Dave,
Thanks for the definitive answer on this one. I guess I too was worried about stripping a thread. I'll get out bigeest wrenches and give that thing some real stick.
Once again the CTB has given me the info - Thanks everyone. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-10-15 43859
Dave & Mark
Thanks Dave I was not sure how large his pipe fitting was there for used the term a lot of torque. I thought about but did not describe large pipe wrenches, cheater pipes, straining and sweating. ....
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley
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2002-10-16 43865
Some place way back in my tinkering history I think I put a coupler in a pipe just so I wouldn't have to go huge in the power department to get a valve aligned right. There probably are problems with that solution too. I seem to recall having to put a pipe wrench on the coupler to get both sides to seal. ....
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