How to find "black pipe" leaks

[twostory]

I installed my Mr Heater 45,000 btu heater this weekend. I have a propane tank outside the garage. I put a regulator on the tank with a rubber hose.

The hose connects to a black iron pipe at the exterior side of the wall. The black pipe has six 90 degree fittings, 2 unions, and a few couplers. The pipe is 1/2 inch. The black pipe goes all the way to the heater connection.

I used the yellow pipe sealant on every connection and all the fittings are firmly tightened with a 14 inch pipe wench. I bought the pipe and fitting at home depot.

My problem is the system does not hold pressure after one hour. I turn the gas to pressurize the pipe, then turn off the valve on the exterior wall where the rubber pipe connects to the black pipe. Thus removing the propane tank, regulator & rubber hose from my system.

After one hour, I turn the propane tank back on, then open the exterior wall valve. I hear the gas rush into the black pipe system. I have sprayed soapy water on every fitting and do not see and bubbles. I can not smell any gas, even if I leave the propane tank connected for an hour.

I also have a cut off valve right at the heater. If I run leak test, with the "heater" turned off, the result are the same. So I do not think the "heater" is leaking gas.

My question, any thought on how to find my leak?

Thanks in advance...

 

[walrus]

My question, any thought on how to find my leak?

Thanks in advance...

Unhook the piping from the tank and from the heater, put a tee in the line with a gauge and use air to test it. Black iron piping should be able to handle up to 150 psi. soap the fittings

 

[ddrewyor]

Re: How to find "black pipe" leaks

I had a leak one time on the surface of an elbow, not at the connection. It looked to be very porous almost like a rough casting and some paint had filled in a crevice. I kept checking every connection but no luck. I finally ran air pressure in the line, the paint blew off and there was a pinhole. Probably one in a million, but you might want to take a look at the fittings also. Good luck

Dave
________
YAMAHA GX1 SPECIFICATIONS

 

[kbs2244]

It is the couplers.
They are designed for water not gas.
Go to a plumbing supply house and explain what you are doing.
They will have couplers with better matching parts.
Be prepared to pay for better stuff.

 

[twostory]

Thanks for the advice. I will get some more fittings so I can put some air pressure in my system to figure out were the leak is.

I will let you know what I find.

 

[walrus]

I've never heard of a blk iron coupling made for water and not gas. Your pipe dope might not be compatible with propane

 

[Ron Lombardo]

Exactly ... teflon pipe dope disolves ..I;m not sure you will find that in wrtiting ..but ask your gas comapny ..we use gray pipe dope ... leak detector spray or air pressure should reveal the leaks .. we use a Magnahelic guage 5lbs or a low pressure guage 5 lbs ..the sell it with a air valve conenction you can pump it up with a bike pump.

Ron

 

[walrus]

Exactly ... teflon pipe dope disolves ..I;m not sure you will find that in wrtiting ..but ask your gas comapny ..we use gray pipe dope ... leak detector spray or air pressure should reveal the leaks .. we use a Magnahelic guage 5lbs or a low pressure guage 5 lbs ..the sell it with a air valve conenction you can pump it up with a bike pump.

Ron

The can of dope should say what its compatible with. If not google their website and find out. I use Rectorseal no. 5 for gasoline, I think its rated for use with propane??

 

[rickairmedic]

A spray bottle with several drops of dish washing liquid and filled the rest of the way with water . Spray it on the pipe and fittings you will see bubbles where its leaking do a small section at a time so you can watch for the bubbles .


Rick

 

[Chetter]

I have the same heater installed and I will warn you not to pressurize the lines with air while hooked to the heater, you will damage the heater. The pressure for the LP is only like 2 lbs by what the tech guy said at Mr Heater when I called to ask what pressure they run. The regulator controls the pressure. I hooked mine the same way as you, 1/2" black pipe with pipe dope, ball style shutoff inside, and 2 40lb bottles and an automatic regulator that switches from the empty to full tank. All parts I used are good for water, gas, propane or air. It works perfectly and I leave mine on 24/7 at 52 degrees to keep my garage dry and warm. I can go out and work on my cars, wash and wax without being cold.

 

[flat350]

The couplings that come on the pipe are not couplings they are thread protectors , a black mallable coupling will have a cast texture . Don't use the thread protectors as couplings they will leak . Some steel pipe can have a welded seam running it's length very rare for it to leak but have seen it happen . A cheap union or gas valve are good for leaks also , as already posted spray it all down with a little soapy water with some pressur in it and it will bubble where it leaks .

Steve

 

[Aceman]

The couplings that come on the pipe are not couplings they are thread protectors , a black mallable coupling will have a cast texture . Don't use the thread protectors as couplings they will leak .

Exactly what I was going to mention.

 

[RPH]

Cheap fittings on the market today can have small pin hole leaks where you would'nt expect one. Spray the entire pipe and fittings down with soapy water. We have found this on some cheap fittings while building our machines. Purchasing sometimes saves money in the wrong area!

 

[malibu101]

Cheap fittings on the market today can have small pin hole leaks where you would'nt expect one. Spray the entire pipe and fittings down with soapy water. We have found this on some cheap fittings while building our machines. Purchasing sometimes saves money in the wrong area!

I've been in this nightmare. Piped in a compressed air system in my dad's barn, all black iron. When done, under pressure, heard a leak.
A tee had a very small hole in it. Virtually invisible, but enough to leak.
Had to cut, thread, unioun to repair. LOTS of needless work for a bad fitting.
Check them real close! I do now.

 

[kbs2244]

When he said "couplers" I thought he was refering to the "cheaters" that let you work from both ends with threaded pipe and then join them in the middle of the run.
If he didn't use dope, I have to agree that may be the problem.

 

[twostory]

Well I got some new fittings, detached the heater and propane tank and put 20 psi of air into the pipe system.

I found that one union was leaking. I still have a slight leak somewhere, so I will check all fittings for a pin hole leak. As for the leaking union, I replaced it with another one, the new one does not leak.

I have Gainger near me, are the grainger $10 unions any better than what home depot sells?

Thanks for all the advice, I will post more info after I find all the leaks.



To avoid confusion, the following pictures are what I used.

1 - union
2 - elbow
3 - coupling
4 - Tee
5 - RectorSeal Thread Sealant No. 5 on all the fittings. This is yellow, soft setting and rated for gas.

 

[Chetter]

I used that same sealant, works great, no leaks. Good luck..

 

[walrus]

To avoid confusion, the following pictures are what I used.

1 - union
2 - elbow
3 - coupling
4 - Tee
5 - RectorSeal Thread Sealant No. 5 on all the fittings. This is yellow, soft setting and rated for gas.

Looks fine to me. good luck finding the leak

 

[flat350]

The Rector Seal is O.K. for gas and it's not always the cost of the fittings , I've had better luck over the years with domestic fittings opposed to imported but not always . The unions that you are using are called " ground joint unions " some people will tell you not to put any pipe dope on the center mating surface , you'll find that sometimes a little dope there is all that it takes to stop it from leaking .

 

[Elroy]

The couplings that come on the pipe are not couplings they are thread protectors

If that was true, why does the mill only install them on one end of the pipe. And if this were the case why the hell would they tap both ends of the coupler?

Elroy would venture to say that the reason you are making these clams is because typically a mill supplied section of T&C pipe will incorporate a steel coupling and not a cast iron coupling. Steel couplings require greater torque to seal via thread deformation than a malleable cast iron coupling.

Please be advised that Elroy is NOT singling you out for reticule, He is simply attempting to preventing false information from getting a foot hold and being propagated as fact.

Mill supplied couplers are in fact couplers. Thread protectors are the red and blue plastic caps.

You also want to be cautious that "electrical" couplers are not mistakenly applied in pressure piping applications as these have straight internal treads and are NOT properly tapper to generate liquid or gas tight seals regardless of what kind of "dope" is applied to the thread.

 

[jadon]

Don't know if it has been mentioned, or if you checked, but in the past I have tracked down hard to find leaks to be the result of a valve leaking internally.

I have been reading this forum for months and never have posted. When I read "find" and "leak" I felt for you so here is my first post!

Hope I helped.

 

[therealjakeg]

Gas? call the gas company if you think you have a leak they will find it. Im a gas guy.

 

[larry4406]

Elroy - you seem to talk with some experience but the smooth threaded "couplers" that come on black pipe I have been told are an aritifact of the pipe manufacturing process that are left in place for additional duty as thread protection with the other end having a plastic cap. I know for certain that in my area the inspectors will bust you every time if they see one of these installed in a system. In our area, those "couplers" are thread protectors and become dumpster food.

 

[mmg440]

LP gas pressure can change with temp and is a lot more affected if only a gas as in the line. Not liquid/gas mixture like in the tank. The onrush flow heard when turning the valve on may not be indicated a leak. It may only be the changes in pressures balancing out. Cap off the heater end (to eleminate and protect the heater) of your line and use air pressure to first check for leaks then install a temp gauge and pressurize it and see if it holds.

 

[flat350]

Elroy - you seem to talk with some experience but the smooth threaded "couplers" that come on black pipe I have been told are an aritifact of the pipe manufacturing process that are left in place for additional duty as thread protection with the other end having a plastic cap. I know for certain that in my area the inspectors will bust you every time if they see one of these installed in a system. In our area, those "couplers" are thread protectors and become dumpster food.

Ditto for the inspectors in this area , don't try to use them if you want to pass inspection . To Elroys statement that they are true couplings , run a pipe ****** with a tapered thread into a mallable coupling and then try it on the " thread protector coupling " and you will see a world of difference as to how it makes up . Most of the couplings that come on the pipe will make up until they bottom out on the unthreaded portion of the pipe , if that was a true tapered thread on the coupling it would'nt happen that way . Say what you want about the thread protector couplings but I'll save myself a lot of time and aggravation by not using them at all !