(Not a) Gas Line Union Leak

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Geobrick, Mar 3, 2021.

  1. Geobrick

    Geobrick Member

    Joined:
    Jan 30, 2010
    Location:
    California
    [Update- This turned out not to be a Union leak but there's still some good information on that topic here. By post 14 I realized the leak wasn't at the union and in post 53 I isolated the leak to the service riser pipe buried about 20" underground. Enjoy the process!]

    Need some help on the best method and tool for tightening (or loosening for removal and replacement) a Union fitting on a natural gas line especially if it's in a tight location (I'll add a picture to show the obstacles).

    Background:
    The gas company recently walked through our neighborhood looking for gas leaks (mostly looking for leaks on their side of the meter). They found a leak by my service entrance and isolated it to a line going to our pool equipment. (They turned off all the equipment valves, pressured the line it and watching for a pressure drop. The pressure did drop pretty fast so they turned of the valve feeding that line and red tagged it. It was beyond their scope to find and fix the actual leak (which is understandable).

    I decided to attempt finding the leak myself. I put a pressure test gage on the line and pressurized the line to 8lbs (all equipment valves off along with the valve feeding the line). I used some gas leak detector spray on all the visible fitting connections (above ground) and saw some bubbling on the Union. The pressure was down to 6lbs in a half hour and down to 3 within 2 hours.

    Here are some photos. The first being the union on the pressurized line (8lbs) I was checking and the second picture is another line that wasn't suspected but also shows bubbling. That line is currently in use and only has the normal operating pressure (post meter). The first union is about 13 years old and the 2nd is 21 years old (as old as the house). Should I try tightening them first or would you just replace the unions?

    Leaky-Union-IMG_3236.jpg Leaky-Union-IMG_3237.jpg
     
    Last edited: May 1, 2021
  2. Terry

    Terry Administrator Staff Member

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    I would tighten first. What do you have to lose?
     
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  4. Geobrick

    Geobrick Member

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    Nothing to lose beyond what's already lost. I tried initially but it wouldn't budge.

    I'd welcome any techniques or suggested tools I should try. One of the unions is easily accessible the other is between a wall and the meter.
    I have two 18" pipe wrenches and some 12" crescent wrenches. Do I need some thing bigger or a different type of tool (like an open ended square with a 1/2" breaker bar - I'm not sure what that's called). Should I tap the union nut with a hammer?

    Here's 2 pictures of the area showing the Union on the right side between a wall and the meter.

    Gas-Service-1-IMG_3238.jpg Gas-Service-2-IMG_3239.jpg

    I haven't worked with large Unions before. Everything else I've done with plumbing required more nuanced tightening (like compression fittings).
     
  5. Tuttles Revenge

    Tuttles Revenge In the Trades

    Joined:
    Oct 15, 2014
    What wrenches do you have that you're working with? How close is the union to the wall? Before attempting to tighten the union. I would suggest loosening it some, then tightening it. If that doesn't work, then take it apart, just the nut and see if its lined up properly. if not you may have to sorta tweak that riser til it is lined up. Then tighten it up. It should be a ground joint union, so pretty easy and good seal.

    What material of pipe is that in the ground? Is it covered in a Yellow plastic coating? Black iron isn't supposed to be installed within 6" of the ground where it will be in wet/damp condition.. and its not supposed to be buried unless its coated to prevent corrosion. Hopefully its got a proper coating.
     
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  6. Geobrick

    Geobrick Member

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    I have two 18" pipe wrenches and a couple of 12" crescent wrenches. If I need something bigger or there's a better tool out there, let me know.
    The larger pipe coming out of the ground on the right seems to be a coated metal pipe. I agree it doesn't come high enough out of the ground before connecting to the (I believe galvanized) elbow. The elbow joint was previously wrapped with tape suitable for use underground (I removed the tape to check for leaks and there was no leak there). The pipe about 3' down that runs to the pool equipment is plastic.

    The distance from the union to the back wall is 2.5" and the distance to the right wall is 8".
    The smaller union on the left connects to a green coated metal pipe.
     
  7. Reach4

    Reach4 Well-Known Member

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    Sep 25, 2013
    Location:
    IL
    I like my 15 inch Milwaukee adjustable wrench 48-22-7414. Opens to about 1-5/8 (45 mm).

    But the first tool you should get is a digital caliper to measure what you need. You need two wrenches I think.

    [​IMG]
     
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  8. Jeff H Young

    Jeff H Young In the Trades

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    I have a machinist background from 30 some years ago Lost all my tools by theft a roll away and kenedy top box. But went a bought a cheapie digital caliper it is invaluable around house and it works good even does fractions and metric but I find decimal inches best. Reach 4 you really like that tool me too!
    To the op I use 2 18 inch wrenches on 1 1/4 or 1 1/2 .
     
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  9. Tuttles Revenge

    Tuttles Revenge In the Trades

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    And to be clear. The leak is not at either of the tapered threads of the ends of the union. The leak is coming from the Union nut.. so between the ground joints of the union / the middle.?

    18's should be fine for that as long as there is room to get the jaws all the way around. I would take the union apart, but leave it on the pipe. Clean it up with a brass wire brush to get any debris out of the threads (brass brush would be best to not scratch any of the steel surface). lubricate the threads of the union with a drop or two of oil and then reasemble making sure the two sides line up.
     
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  10. Jeff H Young

    Jeff H Young In the Trades

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    could be other leak/s just stop that one and retest
     
    Last edited by a moderator: Mar 4, 2021
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  11. Geobrick

    Geobrick Member

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    Yes. Could be other leaks and I will retest after stopping these but I needed some advice on the best tools for the job of tightening the unions.
    I'll try again with the tools I have. If that doesn't work, I'll get a bigger pipe wrench or call a Plumber.

    Is it ok to attempt tightening a Union with gas still in the line or should it be purged?
     
  12. Geobrick

    Geobrick Member

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    Yes the leak appears to be at the union ground joints with the bubbles appearing at the union nut. The parts where it connects to the pipe seem fine right now. I'll see if I can attempt tightening it today. If not today, tomorrow for sure.

    From what I read about these unions, they have a beveled mating section with materials that will seal when pressed together by tightening the union nut. So no sealant is required at the union side, correct? Should I put something on the union side threads to help with tightening the nut and ease of removal in the future (besides a bit of oil)?
     
  13. Jeff H Young

    Jeff H Young In the Trades

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    Just tighten them up in a perfect world unions don't leak . In my world I fix leaks that never should have occurred and a little dope on union has fixed countless leaks. but they normally have brass imbedded on mating surface, hence Tuttles Revenge statement of caution around the mating surface. His advice is good a more proper way . but mine isn't going to hurt a thing , 15 minute job whichever way try the oil , or try my idea , or ? look for a new idea. let us know how it turns out we like to hear if you fix it or if further leaks show up
     
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  14. Tuttles Revenge

    Tuttles Revenge In the Trades

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    pipe dope on the two mating surfaces fills up any minor misalignment or gaposis. The oil or any lubricant on the threads just aids in reducing friction and allowing a bit more Umph with less effort.
     
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  15. Geobrick

    Geobrick Member

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    Location:
    California
    Jeff H Young may be right. I don't think the Unions are the problem.
    I think the bubbling in the photos above are created from spraying the Camco leak detector fluid onto the joints. There's no active bubbling going on at those locations (or at any of the visible joints). If I put my finger over the bubbles, they dissipate with the fluid still at the joints with no new bubbles. I probably need a better way to find leaks. I filled the pipe with air at 11 psi and saw no sign of active bubbling or heard any air leaking yet the pressure was down to 10psi in less than 15 minutes and much lower an hour later. Once I verify the pressure gauge isn't leaking (it's new), I'll dig a little deeper into the ground to inspect the joint at the underground plastic pipe. It's the only accessible area left to check. The rest is under cement. On the plus side, the gas company guys were sensing a leak down in the dirt at that location so there's a chance it's there.

    Does anyone have a recommendation for a good gas leak detector similar to what the gas company uses?

    Before I figured out the leak probably wasn't at the union, I was able to open the smaller union and close it back up again and I was able to tighten the larger union (by maybe about 5 degrees). I used a rubber hammer to help loosen the small nut and did the same to get the large one to budge a bit. It didn't require a lot of force.

    Here some pictures:
    Opened-Union-1-IMG_3240.jpg Tightening-Union-2-IMG_3245.jpg Underground-Pipe-IMG_3244.jpg Elbow-to-underground-pipe-IMG_3243.jpg
     
    Last edited: Mar 5, 2021
  16. Tuttles Revenge

    Tuttles Revenge In the Trades

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    Yeah.. out of the spray bottle the solution will be agitated and form bubbles.. but if you have a leak, you would see the bubbles growing. If you brush it on you may get less initial bubbles. Some of the detect solution comes with a dauber built onto the cap. But even with the small bubbles, you are looking for actively expanding bubbles.

    I bought a Klein detector that I like.. I can easily change the sensitivity on the front and get a visual display.

    All leak detectors will get false positives from a variety of chemicals... like pipe dope.. which is on threaded pipe.. that was annoying to figure out by trial.
     
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  17. Jeff H Young

    Jeff H Young In the Trades

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    Geobrick, I wasn't questioning a leak at union but thought the bubbling small to drop that fast.
    Seeing the tracer wire tells me there is likely PE or PVC underground . I'd say dig up and expose down to first 90 on both ends. Is this for pool heater? disconnect and cap at unit soap up everything exposed first. chances are good a leak will be found near the ends . I'd say do this first before a pro detection is hired. Depending on other factors like condition of piping and ease of replacement you might decide to run a new line as opposed to chase leaks on old pipe in poor condition. on other hand the plastic might be in good condition. So some discovery digging may be in order
     
  18. Geobrick

    Geobrick Member

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    Thanks. Will check out what Klein has and any others that get recommended.
     
  19. Geobrick

    Geobrick Member

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    Location:
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    There's a BBQ, a Fire pit and a pool heater on that branch. The valves at the heater and pit are off and I put the gauge on the bbq pipe. There's no easy access to the PE under ground at any location except the area shown in the picture. The good news is, that's where the gas company was detecting a leak and they were putting their sensor probe into the ground at that area. I'll dig that up next to inspect that junction. Hopefully that's the problem becuase if it's anywhere else, it will require breaking up cement. The pool was installed in 2008 making the underground pipe 13 years old.
     
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  20. Tuttles Revenge

    Tuttles Revenge In the Trades

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    as silly as it may sound. Call 811 and have them locate the utilities in the area you're planning on digging. You don't want to put a shovel through the gas companies line without those marks to CYA. Its free and its required.
     
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  21. Geobrick

    Geobrick Member

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    Jan 30, 2010
    Location:
    California
    Not silly at all. The gas co was out here and they started the digging in that area and their main line is about 2 feet away and goes down then to the left. I also won't be using a big shovel or pickaxe. I'm going to dig like an archeologist to clear the area around the pool gas line going into the ground. I was there in 2008 when they dug the trench so fortunately I remember what's in that area.
    But your recommendation is always a good one.
     
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