Leaking Gas Pipes... 3rd attempt :( Any Tips For Me?

Old 12-23-04, 10:04 AM
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Leaking Gas Pipes... 3rd attempt :( Any Tips For Me?

Please read- Questions at bottom.

I installed a new gas system in a rental property. I have a Rigid pipe threader and used a metal cutting disc in my chop saw to assemble the system. I used black iron\steel ? 1" pipe. It feeds from the meter to the heater\ h\w heater & stove.

At first I used the yellow gas teflon tape on all the joints. I topped each piece that I brought a foot up through the floor from the crawlspace with a ball valve.

With all valves closed I put pressure in the system. It was holding pressure over night, but I would fill it with 15lbs+ then come back the next day and there was 1 to 2'bs in there. Not enough to register on my gauge but enough to make a pisst sound when opening one of the valve. So it held a little pressue but not enough at all.

I was told the teflon tape is junk, so I went out and got some pipe joint compound ie: pipe dope. I took the entire system apart, wire brushed all the threads clean.... apllied the dope (very excessivly) and reasyembled everything.

This once again didn't hold pressure. I put in 15lbs and the next morning zero. Pissed I filled a bottle with soapy water, put 30lbs+ in the system and crawled around looking for the leak by sprayin the water on the joints.

I found one leak in a "T" joint.... that jusy happens to be in the middle of everything... have to take it all apart again... well 1\2 of it. Is this common, to have a leak or 2 and have to check the system, retighten pieces and so on? Or do the pro's get it right on every time?

Can anyone give me tips on working with this pipe?

I cranked everything as tight as I could by hand.

Is it possible to over tighten these pipes? Do the fittings "strech" or distort any if there over tightened and reused?

I keep hearing differrent stories and haven't talked with an "expert" yet.

Please give any advice you can... I gotta get this done asap.... it's cold here need to get the gas back on to finish the renovation... the propane jobsite heater eats tanks..... $$$

Last edited by Hillegas; 12-23-04 at 10:06 AM. Reason: Adjusting Title Mistake
Old 12-23-04, 03:41 PM
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Start with checking the threading dies first. The fitting should turn on by hand (with no dope) 3 turns. If less then the threads are too shallow, more, threads are too deep. Should not be 1/4 turn more or less.
Teflon tape and pipe dope compound are not made to seal the joints. They are a lubricant to get the maximum amount of make-up on the threads. I have never seen the yellow tape (teflon) but I understand it is code in some States. If I use teflon for gas I also use dope. I prefer RectorSeal #5. It is yellow in color and is rated for just about every type use.
For 1" pipe I would be using 18" pipe wrenches. I always go for the lightest but also what will give me the leverage I need to tighten effectively. Not likely you streched the fittings. I would be using valves made for gas instead of ball valves.
Hope this sheds some light on your problem. Reply back if you have further questions.Good luck.
Old 12-25-04, 10:47 AM
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I was under the impression the ball valves I used could be used for gas. It said so on the label?

I didn't think of using teflon tape & pipe dope, at that point I figured it would be to much. But like you said it's not meant to seal the joints.

I'm just going off memory, but I believe that I can turn the pipe just about 3 times, mabey more but I know it's not less.

If the threads are to deep, how is that fixed? I'd have to redo the entire system?

Is there any type of solvent of chemical I can use to clean the dope off the pipes? If I have to take the whole thing apart again I'm going to clean all the connections, try how many turns i get dry. And if it's ok then re assemble with both tape and dope.

Hopefully this will be the last time.

How much pressure should the system hold and for how long?

10lbs? 20lbs? etc.... If I put 20lbs in the system, how long should it hold for?

Is it normal to have some type of a loss? I have no idea what psi my gas service is coming out of the meter. So how much psi should my lines be able to hold?

Thanks for your reply, I apreciate the help

Mike Hillegas
Old 12-25-04, 10:59 AM
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For instance, if I put 20psi in the lines and come back 2 weeks later. It should still have 20psi?

Guy in the township office said it only had to hold 10psi over night. But he wasn't the inspector.

If my line holds 10psi over night, but the loses the pressure on the 2nd or 3rd day is that ok?

Makes no sense to me?

At worst, if I decide to give up, any local plumbers in the south jersey area care to look at my problems and fix for $$$... lol
Old 12-25-04, 12:19 PM
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Two cents.
I grew up in the East Texas oilfield with natural gas "everything" (central heating, space heating, gas fireplace logs, cooking, water heaters, fixed outdoor grills, etc.), and we never used anything but pipe dope.
I also worked as a roustabout for an East Texas oil and natural gas pipeline company a couple of summers in college, and they never used anything but pipe dope...and that was on everything up to 8" threaded heavy duty pipe for high pressure natural gas and crude oil. (We welded the larger stuff.)
I prefer teflon tape for water plumbing, but I always use pipe dope on gas.
I knew of a few East Texas old timers that would use plain dry bar soap for thread lube on gas space heater flared fitting connections when they would drag them out for the winter, but I do NOT recommend that. LOL
Go with pipe dope and shower down on the pipe wrenches. Can't go wrong.
Old 12-25-04, 04:15 PM
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Test 15 lbs for 15 min is the normal test, should not lose any air on test.

Use a 30 lb test gage.
Old 12-25-04, 08:08 PM
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Thanks for the replys.

I'm using a air comp. gauge that reads up to 120psi. I can't seem to find a gauge anywheres that'll read 30psi and have a 1\4 or 3\8 thread on it. Where can I get one?

So if it holds 15lbs for 15 min it's ok?

I have no clue but I thought it would be longer then that. What if after 15min it leaks?

Last edited by Hillegas; 12-25-04 at 08:21 PM. Reason: Fic Mis-spelling
Old 12-26-04, 06:21 AM
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You can find them here.

Test Gages by Plum Best

Reason for 30 lbs is if there is a leak you will know real soon, if it loses air then there is a leak, you will need to take apart pipes and reassemble them.

The test gage can not exceed more the twice the pressure your going to test at.

There should be no leak, no lose of pressure.

Done many test and returned after inspections to remove the test and gage was still at 15psi, gas in static state is 1/2psi.

Last edited by Plumber2000; 12-26-04 at 10:03 AM.
Old 12-26-04, 08:28 AM
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Hello: Hillegas

The advice you have obtained thus far is highly accurate.
My 10 worth of additional info....

Local codes for air pressure testing vary. 10 to 15 or 10 to 25 lbs for about 4 to 6 hours in some areas. No leakage should be noted regardless of the pressure testing lbs or time frame but there has to be some reasonable time limits.

Or an inspector would not be able to complete testing and code pass the building permit, for that aspect of the construction phrase, during tract building construction.

The gas pressure out of a natural gas meter is about 7-10 inches of water column...(WC) which is much less that 1/2 pound pressure. So a 15-20 air pressure test over a time frame of 12 hrs to 24 hours or per local codes is enough.

Ball valves (used for gas isolation valves) are okay and meet all codes. Ball valves have all but replaced the formerly used core valve shut off valves in many areas. Ball valves may or may not be all that is currently available in your arear or currently the code in many areas of the USA.

Pipe thread compound (pipe dope) is more widely used than pipe thread tape. Makes for easier, faster and more accurate assembly. Amount used can not be too much as it can be with pipe tape.

Excessive compund simply builds up externally, for the most part. Excessive pipe tape can cause binding of the threads. Which gives the false impression of a tight joint which may not be true in all instances. Thus, gas pipe (iron or steel, galavnized, etc.) thread compound is best...IMO.

In order to do an accurate air pressure test against any type of line isolation valve (ball or core type) is also risky. All exposted ending pipe where an appliance is to be later connected should be capped off.

No shut off valve installed for an air pressure test. Code in many areas. Risks of minor valve leaking or sppeking occurring during an air pressure test using those pressures. The valves are not designed to with stand high pressures for the most part.

Be sure the gas meter is NOT connected to the gas line. The inlet line, to the house, etc. must be removed from the meter, if a meter is currently installed. The inlet line to the house, building and/or structure must be capped off. Unless the pressure test is done at that location. And not done at another location.

All the above is an assortment of variations to several applications and/or methods. Offered to compliment the already provided professional advice offered. Hope it helps.

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Old 12-26-04, 09:00 AM
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The meter isn't installed. This is in an older row home. The gas company came and removed the meter. The meter was inside, in the back utility room.
So as of right now, the main gas feed comes in, up through the floor and is shut off and locked.

I installed the new gas lines from that point, to all the areas that need gas. Also sent a new line from that location outside for the vent or whatever it is.

Thanks for everyones replies. I guess I'm having bad luck. I'm going to take the system apart and reassemble. Since I've located the leak, hopefully I'll be able to get the system to hold air once again. And if it'll hold 15lbs overnight then I should be fine.

I guess I should also install a length of pipe above my ball valves and cap it so there no chance of leakage through the vavle.

I'm glad I found this site.

One more question..... is it normal to have to go back and take apart \ reassemble? Do the "pros" have leaks too.....


Thanks everyone, hope you all had nice holidays
Old 12-26-04, 09:18 AM
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DAMN! Excuse my language...

I went to that plumb best website, and theres exactly what I need, a cap with a valve and a gauge that read up to 30psi.

But I can't buy it. It says they won't sell to homeowners and contractors which happens to be me

Can someone get me a gauge like this?

I've checked home depot, lowes, and 3 local supply houses and none have what I'm looking for like in that link.

Is there any other websites that sell what I need that I can buy from?

Thanks again everyone.
Old 12-26-04, 09:43 AM
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Try here there is no picture of it but it could be the one you need read the list.

Plumbing World
Old 12-26-04, 09:56 AM
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the main gas feed comes in, up through the floor and is shut off and locked.
Your newly installed line cannot be already attached to the gas companies supply line. Their own shut off valve can be leaking. Therefore, the air pressure in the line used for testing can be and most likely is leaking backwards into the gas supply header pipe.

Header pipe is the gas companies supply pipe (manifold) which supplies nat gas to multiple meters. Most commonly used on multiple dwellings. (Condos, apartments and/or any variety of multple housings or building structures, etc.

Header pipes (manifold supply pipes) usually but not always are installed horizontally and have two or more meters on them. Each having it's own seperate shut off valve. Variations apply, depending on meter locations.

Primary point:
The entire newly added gas line you installed cannot be connected to anything. Capped on all ends. Including the gas pipe supplied by the gas company.

As stated above, "Their own shut off valve can be leaking. Therefore, the air pressure in the line used for testing can be and most likely is leaking backwards into the gas supply header pipe."

I have been to far too many such installations as you describe to find newly installed gas lines which a leak free air pressure test cannot be obtained simply because the new line was installed onto the existing gas supply line.

CAUTIONARY NOTE: (May or may not apply in this instance)
Air pressure testing, while any gas line is still connected to the gas supply line, with a shut off valve installed, on a header gas supply manifold pipe!

Air pressure highly exceeds water colume pressures. Any bleedback past an isolation line backwards flow into the nat gas supply line will create problems. Severe to minor depending upon conditions, etc.

Excessively high gas pressure damages gas appliances internal regulators and controls. Over pressurizes burners, creates noisy burners, exceesively large burner flames and allows leak to exist where none where prior, etc!

Never air pressure test any gasline still attached to gas company supply lines and/or equipment.

FYI Note:
Excessively High Air pressures used during testing of gas lines for leaks, when lines are attached to gas company lines or equipment, causes backflow air pressure through shut off valves to bleed backwards which can and will overpressure street pressures too!

Which effects district pressures. Which sets off my office equipments alarms.... .... Service persons must be dispatched to the effected area(s) immediately, if not sooner. I hate when that happens. And it happens daily somewere in the vast areas served. Frisco to San Diego.

Alarms are preset to detect pressures in either direction, up or down. Any increase or decrease outisde of alloweable limits, sounds the alarms and flashes strobe lights...etc.

The natural gas pressure, from the street into the gas companies regulator is not usually more than 30-35 psi. After the companies regulator, outlet side into the meter, is W/C (water colume) pressure...7-10 inches.

Disclaimer notes: (For the purpose of clarifications)
All the above refers strictly to Nat gas only. Not propane.
Disclaimer added to clarify and avoid confusion....
Also lessens the #'s of PM's I get for posting "My 2 to 10 Cents Worth".....

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