Method for leak testing black pipe

[ripsnortMN]

I got my modine hotdawg hooked up and am now testing the black pipe. I have a shut-off at the heater so i dont damage the valve inside the heater. I leak tested it once and had a leak at an elbow. I fixed that and put 10psi back into it and it has held for 20 minutes. How much pressure should i be pumping into the lines during the test? Also how much psi will a regulated propane tank actually put on the pipes?

 

[lametec]

LP for home use is typically regulated to 6 ounces per square inch. That's 0.375psi.

Black pipe will handle over 100psi easy, so if you want to up the pressure even more for leak testing you can. If it doesn't leak at 20psi it won't leak at 0.375psi either, though.

 

[ripsnortMN]

54 views and one response...you guys are killin' me!

 

[Mike Moriarty]

20 psi overnight.

 

[porschedude996TT]

I just had mine inspected last month. I was testing and holding 120psi for days. It took me a couple of tries to get it leak free at 120psi and found the leaks using the Bubble Leak Check Meathod (Soapy water to make bubbles). When the inspector came over I think he only wanted 20psi for 15-20 minutes. I used something like Rectoseal #5. I think it does a better job than Teflon Tape.

 

[ripsnortMN]

Wow 120psi? Thats a little overkill isnt it? Considering a gas line puts out maybe 1 psi or less. I did 10psi over night. I have yet to check it this morning. I will let you guys know if its still steady.

 

[redsky49]

Typical operating pressure for low pressure natural gas lines is 5-7" w.g.
This is less than 0.3 psi. Confirm actual operating requirements with equipment requirements.
Incoming gas (before the pressure regulator) for natural gas is usually 2 psi or less. Propane is different, and may have substantially higher upstream pressures.
There is no need to test at such high pressures, but no harm either.
Generally piping is tested at 200% of operating pressures.

As always, offered only as opinion

 

[nate379]

I just hooked it up to the meter, kicked on the gas and sprayed a little soapy water on the joints.

 

[ripsnortMN]

Last night i put 10 psi in the system. This morning the gauge read 6 psi but it was also 10 degrees cooler out there than it was last night. Do I have a very slow leak or is it just from the temperature change?

 

[bgarrett]

When the inspector came to my house, he suggested 80 pounds overnite so thats what I achieved

 

[ripsnortMN]

When the inspector came to my house, he suggested 80 pounds overnite so thats what I achieved

Did yours drop any pressure at all overnight?

 

[russlaferrera]

I put 175 psi. Checked for leaks with dish soap. Had one leak at an ell. Tightened it. My gas installer put 10 psi and hooked everything up If there was no leaks at 175, there will be no leaks at 10 psi.

 

[redsky49]

A 10 degree temperature change does not result in a 40% drop in line pressure. Sorry, but I suspect that you already knew that.

Recommend that you isolate piping sections, if able, and soap test all joints, fittings and trim. Sometimes the stem of the gas **** can also leak.

Use an appropriate thread sealing compound, suitable for your application. Frequently that is something other than Teflon tape.

Proper sealing can ensure that a leak-tight installation can be made even with a poorly threaded joint. Despite this, make sure that your dies are sharp and in good condition. Poorly made thread flanks account for a great many leaks. Use cutting oil as directed. Monitor feed and speed and you should have a properly made thread.

Be thorough and you will locate the leak(s). Make sure that your monitoring gauge does not leak.

A soap test solution can be store bought or you can make it yourself with a high suds dish washing detergent mixed 50/50 with water. Go slowly over each test location and view the area for at least 30 seconds. I use a flashlight and small magnifying glass. Once you have confirmed a joint, wipe it clean and move to the next.

This is one case where slow and steady does indeed win the race.

Hope this helps.

As always, offered only as opinion

 

[redsky49]

I put 175 psi. Checked for leaks with dish soap. Had one leak at an ell. Tightened it. My gas installer put 10 psi and hooked everything up If there was no leaks at 175, there will be no leaks at 10 psi.

There is considerable danger in testing piping systems at this type of pressure. You face the possibility (more likely the probability) that a fitting will fail with catastrophic results. The shrapnel from such a failure could injure or kill.

If testing with air pressure, 150-200% (max.) of normal operating pressure is standard.

Don't take my word for it. Call your Bldg. Dept. or talk to a master pipe fitter or a well qualified commercial plumber. Go to the Library and see what is recommended.

Never take safety for granted.

As always, offered only as opinion

 

[ripsnortMN]

It looks like i need to redo my joints. I just pumped 20 psi into it and it droped to 17 psi in a couple hours. I am using the sealant they sell at menards that is for gas piping. It is yellow in color. I cant remember the name. I cant see how it could be leaking. They are pretty tight. I have a 45 degree elbow that I can't get super tight because of the way i need it pointed. I cant have it pointing at the ceiling you know. I have assembled this three times. I found the previous leaks with soapy water. Can I use teflon tape along with the sealant? This is frustrating as hell.

 

[fatboy99]

make sure it's not leaking thrue the shut off valve by the heater un hook your pipe after the valve and see if it bubles there
Brad

 

[Kevin54]

It looks like i need to redo my joints. I just pumped 20 psi into it and it droped to 17 psi in a couple hours. I am using the sealant they sell at menards that is for gas piping. It is yellow in color. I cant remember the name. I cant see how it could be leaking. They are pretty tight. I have a 45 degree elbow that I can't get super tight because of the way i need it pointed. I cant have it pointing at the ceiling you know. I have assembled this three times. I found the previous leaks with soapy water. Can I use teflon tape along with the sealant? This is frustrating as hell.

Can you add a union in before the elbow so you can get the elbow in the right direction and still get the joints tight?

 

[larry4406]

Don't just suspect only threaded joints. I have had many cast fittings that have split during tightening. Also, many of today's import fittings have casting defects and pinholes thru them. Use the soap solution, spray the entire fitting. I pressure tested all my black pipe at 100 psi and soaped 100% of all fittings - the higher pressure enabled me to find the leaks that I could not find at 10 lbs. Once I was leak free, I set the pressure at 10 pounds for the inspector on my gas piping.

 

[nate379]

Isn't black pipe rated to 300psi?

I have worked in shops that had 150psi in the air lines.

There is considerable danger in testing piping systems at this type of pressure. You face the possibility (more likely the probability) that a fitting will fail with catastrophic results. The shrapnel from such a failure could injure or kill.

If testing with air pressure, 150-200% (max.) of normal operating pressure is standard.

Don't take my word for it. Call your Bldg. Dept. or talk to a master pipe fitter or a well qualified commercial plumber. Go to the Library and see what is recommended.

Never take safety for granted.

As always, offered only as opinion

I have better luck with the yellow teflon tape vs the paste. I redid a water heater install in an old house and ended pulling almost all the pipes apart because the paste wasn't sealing well even with teh pipes Bubba tight.

 

[redsky49]

"Isn't black pipe rated to 300psi?
I have worked in shops that had 150psi in the air lines."


You raise a valid point. However, once you remove pipe wall thickness by cutting threads you reduce the safe working pressure to closer to 200 psi, depending on actual pipe size. This is for normal Sched. 40 black steel. The heavier wall thickness Sched. 80 is much higher pressure rated.

Remember that pipe produced under ASTM A-53 is seamed tubing, joined by welding. I have seen split piping!

If the intent is to design for an operating pressure of 150 psi, every component in that system must be rated to safely operate at that pressure. Compressed air systems are such systems, and should be constructed with an adequate safety factor to allow safe operation. However the OP is talking about a propane gas line, not a compressed air line.

For a gas line, different operating requirements apply. A standard gas shut-off **** (isolation valve) that would be installed at the appliance is typically rated for 0.5 psi. Even the main service shut-off valves are, to the best of my knowledge, rated only to 125 psi. By testing a gas line at 175 psi, or roughly 100 times the normal operating pressure, you are going to find the weak link in the system, most likely in a very dramatic manner.

If the gas-fired heater was exposed to these pressures I would suspect that it has been permanently damaged. As a matter of fact, I would be surprised if the heater didn't explode at such pressures.

So the point I am trying to make is that any mechanical system should be tested according to its intended purpose. You don't test a plumbing vent according to domestic water standards for example.

For (generally) any system, testing at 150% of operating pressure, or at the most 200% of operating pressure, is adequate to properly assess the system. Note that this applies to air testing, not hydrostatic testing.

"If some is good, more must be better" does not apply in this matter.

As always, offered only as opinion

 

[ripsnortMN]

I did find two leaks. One at that damn elbow and one on the pipe cap on the drip leg. I am going today to get some teflon tape rated for gas lines and some new pipe dope. This is the pipe sealant that I am using...http://plumbing.hardwarestore.com/52-304-thread-sealant-compounds/pipe-thread-compound--610427.aspx

It says it dries slowly but doesnt say how long it takes to dry. So how do I know when to hit it with an air test?

 

[benjamming]

ASME requires 1.1 times design pressure for a pressurized system tested pneumatically. That is not design pressure of the pipe.

 

[HoosierBuddy]

A lot of good infomation in this thread.

Out on the big pipe I work with, CFR192 of the federal code generally requires pipe to be tested at 1.5 times the maximum operating pressure. This is because a pressure test is not just a leak test. It is also a strength test. That portion of code does not apply on the customer side of a gas meter though so it will fall to the local building inspector or even the local fuel distributor to specify what pressure they want to see.

If you just wanted to find leaks, you could use any pressure you wanted to. The previous poster is correct when he says a pipe that doesn't leak at 100 psi won't leak at 10 psi. What I've learned is the opposite is also true. A gas line that's going to leak at 100 psi will leak at 10 psi too.

So...don't get hung up on the pressure. Get a lot more hung up on finding all the leaks. When you're dealing with gas, any leak in the building structure is unacceptable, no matter how small. Unless you have access to high dollar instrumentation, like a Combustible Gas Indicator (CGI Unit), and even if you do, soap is still the plumber's best friend when looking for leaks.

If you just can't get a fitting to seal...replace the fitting.

As far as pipe dope vs teflon, I much prefer pipe dope (thread sealant). I use the blue Leak Loc brand and if your READ THE INSTRUCTIONS it says to put sealant on BOTH the male and female threads, allow the sealant to tack, and then assemble the joint.

I would especially recommend that method if you are worried about a particular fitting or joint.

Phil

 

[Falcon67]

Isn't black pipe rated to 300psi?

I have worked in shops that had 150psi in the air lines.



I have better luck with the yellow teflon tape vs the paste. I redid a water heater install in an old house and ended pulling almost all the pipes apart because the paste wasn't sealing well even with teh pipes Bubba tight.

Yes - same with my air system I just installed. I pulled down 40' of pipe and a dozen joints that I re-did with tape after the TFE 3000psi paste leaked like it was toothpaste. Toothpaste might have been better, actually. The tape seals.

 

[ripsnortMN]

Well guys I got 40 psi over night. I changed up my method of sealant. I used the teflon tape that is specified for gas and I also use some rector seal in addition to the tape. Just for the record the harveyseal on its own will not make a good seal in my experience.

 

[nate379]

I have not had good luck with teflon paste with black pipe. I think mainly because of the junk "made in China" stuff that is everywhere.

I use a couple 3-4 wraps of yellow tape on it and it's good to go. The white tape works as well, but diesel for sure eats it away. (found that out the hard way)

 

[tcianci]

MY FIL is a plumber and he always seems to use a combination of tape and pipe dope.

 

[ripsnortMN]

Whats the best material to use for connecting the propane tank to the black pipe? I only have to go about three feet between the two. Could I use that flexible line you buy to connect appliances? Or is bendable copper tubing a better way to go?

 

[Falcon67]

If the tank is outside, I would use copper because I think it would weather better. All the outside propane tanks around here have a copper line snaking out from under the hood.

 

[ripsnortMN]

Great thats what i'll do then. I was thinking 3/4" copper rather than the 1/2". I think 3/4" would carry some more volume.

 

[HoosierBuddy]

Contact your propane supplier for the specs they recommend or require.

I absolutely can't imagine you need to use 3/4".

I'm not a propane expert, or even a propane novice...so I hesitate to tell you what kind of copper to use, but if you do it wrong they will likely refuse to fill up your tank for you if they see it. It'd be safer to make a phone call first.

Phil

 

[cicliste]

I got my modine hotdawg hooked up and am now testing the black pipe. I have a shut-off at the heater so i dont damage the valve inside the heater. I leak tested it once and had a leak at an elbow. I fixed that and put 10psi back into it and it has held for 20 minutes. How much pressure should i be pumping into the lines during the test? Also how much psi will a regulated propane tank actually put on the pipes?

LP is like 6 oz/s.i., and natural gas is 2/3 of that. Crazy to think that it's so hell-bent on escaping the pipes! I have found that DIY black pipe has been one of the most difficult, tiring and rewarding things I have done on this renovation. I tested to 3 psi and let it sit for a couple days, plus also brushed soap solution on all the joints. You're not supposed to do DIY gas work around here but I took meticulous care and way way too much time and it worked out fine.

I started out using both tape and pipe dope but then switched to just pipe dope, on the advice of a plumber. The key is to get things super tight. 1/2" pipe takes a very very good pull with a ~14" pipe wrench, but the 1" pipe has to be absolutely nuclear tight!! Use a big wrench and pull like a mofo!!!

I really don't like the plumbing forums where the old guys imply that everything is rocket science. It's _not_ -- you just have to think hard about your plan of attack, take your sweet time doing it, and not ever allow yourself to take a quick hack. Then you must test your work carefully. It's crazy how much they charge, but moreover it really is not THAT difficult to pull off a superb job and there's immense satisfaction in that.

 

[D45]

8 year old thread bump......and no one freaked out?!?!?

 

[jhelrey]

I just about did...

 

[zmaxmotorsports]

A bic lighter.

 

[LS6 Tommy]

It looks like i need to redo my joints. I just pumped 20 psi into it and it droped to 17 psi in a couple hours. I am using the sealant they sell at menards that is for gas piping. It is yellow in color. I cant remember the name. I cant see how it could be leaking. They are pretty tight. I have a 45 degree elbow that I can't get super tight because of the way i need it pointed. I cant have it pointing at the ceiling you know. I have assembled this three times. I found the previous leaks with soapy water. Can I use teflon tape along with the sealant? This is frustrating as hell.

The yellow tape IS teflon and is the proper material for your job. I have seen a few plumbers use both tape and dope. I have never needed to do so.

Tommy

 

[mrobins297aaa]

A bic lighter.

dam you beat me to it...........lol

 

[ripsnortMN]

LP is like 6 oz/s.i., and natural gas is 2/3 of that. Crazy to think that it's so hell-bent on escaping the pipes! I have found that DIY black pipe has been one of the most difficult, tiring and rewarding things I have done on this renovation. I tested to 3 psi and let it sit for a couple days, plus also brushed soap solution on all the joints. You're not supposed to do DIY gas work around here but I took meticulous care and way way too much time and it worked out fine.

I started out using both tape and pipe dope but then switched to just pipe dope, on the advice of a plumber. The key is to get things super tight. 1/2" pipe takes a very very good pull with a ~14" pipe wrench, but the 1" pipe has to be absolutely nuclear tight!! Use a big wrench and pull like a mofo!!!

I really don't like the plumbing forums where the old guys imply that everything is rocket science. It's _not_ -- you just have to think hard about your plan of attack, take your sweet time doing it, and not ever allow yourself to take a quick hack. Then you must test your work carefully. It's crazy how much they charge, but moreover it really is not THAT difficult to pull off a superb job and there's immense satisfaction in that.

Thanks for digging up my 9 year old thread. Leak free for nine years. I will say that the chinese black pipe from the home improvement stores is junk. Horrible fitup and its hard to get it to seal without yellow tape and pipe dope together.

 

[D45]

I have always just used paste (pipe dope), never had a leak

Tape and paste seems like a good idea though

 

[Lelandwelds]

Most of the pipe and fittings are 600PSI WOG. I stuck a magnetic thermometer out of the pump room and wrote the temp and psi (date and time too) on a piece of masking tape. Any pressure in the middle third of the gauge was OK. Main thing was to pick something easy to read.

If a fitting leaks, just replace it. Easier than figuring the reason. I am confident in my ability to evenly wrap tape and spread goop. Chinese brass and Chinese stainless have fewer flaws than Chinese black pipe fittings. Installs are easier if you can standardize on lengths and sizes.

The pipe threader, pressure recording, cleaning and packaging for oxygen service, refilling factory leak check solution bottles with dish soap, etc. was really just for customer confidence. Fewer frivolous call backs if customer confidence is high.

If you really obsess about such things, a helium sniffer is the ultimate. A mechanical or vacuum pump company who works with the semiconductor industry will have the equipment. Just using helium with soap bubbles will find leaks missed by pressurized air or nitrogen.