I watched a licensed plumber install a union in a 3/4" gas line and was curious about one thing: he didn't use any pipe dope or wrap on the flange portion of the union, i.e., the part where the union actually connects the 2 ends of pipe. Of course he doped the threaded connections on the union. Is that OK? Thanks.

although a little pipe dope or grease on a union connection can be beneficial, it is not required for a leakproof joint.

The complete terminolgy for a union like that is "ground union" meaning the mating surfaces are machine-ground to be perfect mates. The metal-to-metal seal is in theory perfect, allowing no leaks. Also, many unions on the market today actually have a soft "seat" of copper or brass alloy, creating almost a gasket.

I, like many others, do like to put a thin coat of a non-hardening teflon dope on the surfaces to ward off corrosion or pitting.

I use the dope to make the nut turn easier, and to permit the mating surfaces to slide together and eliminate any small defects in the metal to metal seal.

Ditto to that.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

ditto ditto to that

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PLUMBERS "Protecting The Health Of The Nation"

the gas company came to turn on the gas and told me I have a leak somewhere in my in-house lines and then split the scene as I now have learned they do. As I have learned from this nice site a leak is nothing to mess with, but is it really $300 for a plumber to show up at the cold scene then who knows how much hourly fee? yep, built in 1927 with rigid steel pipes

Rates are not discussed here but there's quite a bit involved if the Gas Co. shut and locked the gas meter. Paperwork, (Plbg. Permit), pressure testing the gas lines and locating & repairing the leak(s) OR re-piping.

e-plumber
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"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

Yes, if you pick the wrong plumber. Most will show up and then charge you a minimum fee for the rest of the hour, after deducting the travel time. From then on it is charged by the minute, quarter, half, or hour depending on the company's policy. If the do have a show up fee it is usually about $50.00 and may be credited to the final bill if they do the job. But for something like this, I would not even show up unless I was assured that I was going to do the work. You may be lucky. Here the gas company tells you, "You have a leak. We are turning the gas off and locking the meter. After a plumber finds and fixes the leak, and then the city inspector checks the work and verifies that there are not any other leaks, then the CITY will call us, and we will come out the next day to turn on the gas". Usually a 2 to 4 day process, even if the leak is easy to find and fix.

On just about any threaded connection we'll use some sort of thread sealant to reduce the friction when tightening the connection. Also makes removing the fitting/connection much easier when doing service or repair work since the threads won't be locked up. In Arizona for gas lines we are required to use a union with a rubber gasket insert between the two flanges. A union without the gasket is considered to be a water fitting only.

in mass, we are required to use a union which has one of the mating surfaces made with brass or copper.
if the gas company around here locks the meter, nobody but the gas company unlocks the meter. this is done after a permit, repair of leak, test and inspection is done. the gas company uses those little cylinder shaped locks that you stick a skinny key in the end. we don't touch those..period!!

Do you mean that you are not allowed by code to use a typical ground joint black steel union at the appliance?

e-plumber
-----------------------------------------------------------------------------------------------------------------------------------

"The society which scorns excellence in Plumbing as a humble activity and tolerates shoddiness in philosophy because it is an
exalted activity will have neither good Plumbing nor good philosophy: neither its pipes nor its theories will hold water." -
John William Gardner 10/8/1912 - 2/16/2002

Repair your leaking Plumbing fixtures ASAP [www.theplumber.com]
This slow drip will waste 7+ gallons of water per day.

yep , when the gas company shuts it off it is a 2-3 day process.

it takes time ,knowledge and equipment to test for and find the leak then set it up for for inspector (around here they want every thing from the meter to the stop at the appliances tested). then the plumber has to be there or come back after teh inspector and hook everything back up , you call the gas company they come out and turn the gas on then you call the plumber back to relight any pilots unless the homeowner does it themselves.

not cheap

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PLUMBERS "Protecting The Health Of The Nation"

Actaully we can use a ground joint union at the appliances. The rubber gasketed one is a di-electric union that is used when connecting to underground piping. Here, the city calls the gas company after the inspection, so the call may not be made until the following day if he does not contact his office immediately and if the secretary is too busy to do it that day.



Edited 1 times.

e-plumber, if you look at the ground joint of a union, there is a piece of brass or copper in the center. it is not a seperate washer, it is part of the seat.