I was recently told that unions are not allowed on gas lines (black pipe that is) unless they are at the appliance. Is this correct? I was always under the impression that they were permissible but only if they were accessable like in a basement etc. Also an old timer thta used to work in our maint dept swears that the only pipe thread sealant that should be used on black gas pipe is the "blue stuff". Now senility might be setting in on the old guy. Anybody have any idea what thread sealant he might be talking about. The guys that work for me use Harvey's all the time. Never had one leak in 30 years. Does anybody have a favorite and if so why? TIA
-Tony

I think the National Fuel Gas Code allows unions in accessible locations, but some local codes only allow the union at the appliance. Go with what your inspector will accept.

The blue stuff is "Gas tite", "Seal Tite", or something on that order. It is a good sealer for anything, but "messier" since it does not wash out of the overalls.

Any union in a gas line must have a valve in front of it.


Blue stuff might be Megaloc Teflon Thread Sealant.


Companion flanges are code approved when dealing with two points of piping where you cannot gain access to the opposite end of piping.

best pipe dope for gas is rectorseal yellow. i believe it is #5, softset.
only unions allowed on gas are at the appliance. exposed or not, you can't use them. gotta use left-right coupling and nipple.

Packy's been sniffing to much of that old #5 (lol), were did you hear this?, we break into gas lines all the time and always use unions... never had an inspector question them, can't remember the last time I used a L/R coupling.The blue stuff is the best, we use Blue Block and don't get it on you, takes 2-3 days to come off... wife hates it, never comes out of your cloths.

According to the UPC code......

1211.10
Where unions are necessary,right and left nipples and couplings SHALL be used. Ground-Joint unions may be used at exposed fixture, appliance, or equipment connections and in exposed exterior locations immediately on the discharge side of a building shutoff valve. Heavy Duty Flanged type unions may be used in special cases, when approved by the Administrative Authority. Bushings SHALL NOT be in conceled locations.

I pick my DOPE by the job, I really like Megaloc, Hate the Hercules Blue Block For the simple fact it is too messy and hard to get out of the uniforms, I like Oatley TFE paste for larger pipe, 1" and up.

Plumbermandan

Dan, tomorrow I'll have my top supplier do a search of how many l/r couplings and nip's they sold in the last 12 months in my state... will get back to you on this. Yes HBB is messy but "never" a leak with it and thats what counts.

Very true on the Blue Block, I think I have purchased 4 L/R nipple coupling combos EVER, I always use Unions in exposed locations, So I guess I Agree, it is mainly up to the Admin Authority. and what your repore with them is as to what they will REQUIRE from us as plumbers.

Plumbermandan

That may be the most ignored section of the whole UPC.

They don't and have not stocked them for 20+ years.

I used one about 10 years ago, but only because it was in the wall and besides there was no room for the union nut between the pipe and the sheetrock.

I checked today with my main 4 suppliers in Iowa, One in MO and 4 in Denver Co area, 2 in Iowa can get them 2 Have them in Stock, MO Has them and 2 in Denver have them in stock, 1 can get them, and one didnt even know what I was talking about. They Do exisit and ARE used rarely since Most codes DO allow the use of GROUND JOINT unions in exposed locations.


Plumbermandan

I was going to say........I have done repipes where I leave a certain amount remaining...and the word from my local utility.....not the plumbing inspector that anywhere you have a union......a gas shutoff is mandatory so that the average user can shut down the gas to isolate the union from leaking.



I have companion flanges that I will use if the reconnect is going to be buried, otherwise I use the gas valve/union.


Perfect example of using this idea is when you have a black iron pipe poured into a hearth......which is dangerous as hell to begin with.....and no way to get to the other end.

Here we are supposed to use "dielectric" unions with a gasket.

Just when I think I've learned our different practices you posters hit me with something else. I've not heard of die-electrics on gas piping and I've not heard of no ground joint unions on gas.

That's what happens when yon start listening to people from all 50 states, and half of the world.

I have never used Di-Electrics on Gas I have on water, Is that a BOCA code issue, I can't find my BOCA book, Just moved and it is still packed away in the office. I wouold like to know if that is a local code or if it is a General code issue. Let me know , I Love to learn.

Plumbermandan

EDIT.. Supposed to be addressed to HJ, RE: di-electrics on gas



Post Edited

PlumbCat TM 2003


Plumbermandan

It is not BOCA, but may just be a local "hobby horse" for the building department.

Blue block comes off easy with denatured alcohol.....good stuff!....but i use megalock....but ive heard ...grip works better..messy black stuff but sets like epoxy!

Dielectric unions are required by code in all transfers between underground and above ground gas pipe unless electrolysis has been eliminated by some other process. Most inspectors however tend to ignore this one. One inspector told me not to worry about it on a 2" line because they didn't make dielectric unions that big, they do but he didn't know that. I use them all the time in commercial work. Better to be up to code if ever a problem arrives in the future.

This might be an ideal area for CSST. From what I see, a connection to CSST is OK anywhere inside the house. CSST needs nail plates if it goes through a stud, but there should be enough room between studs to install a short piece and join the iron pipes.

Did somebody just say dielectric union? On a gas pipe? Like the same dielectric union that is used to join two dissimilar metals? Where the hell am I?