Unions for steam piping

Bostoner

Are unions allowed behind the wall in a one pipe system? We are re-piping a tight area where access is difficult. A reverse thread or a union would allow the job to be done without opening the walls and ceilings. My plumber said this can't be done. Is that true?

JohnNY

Local codes are what they are and I'm assuming you're in Boston, a city similar to New York. There's no code or practical reason you can't have a union or left-right coupling behind a finished wall. Add an access panel if you don't trust it, but it'll be fine.

jonny88

Agreed

Ron Jr._3

Your plumber might be thinking more along the lines of burying a union if it's a gas pipe .

I agree , don't see any issue with a union on condensate piping being in a wall .

EBEBRATT-Ed

What Ron Jr. said is correct the plumber is thinking gas.

Mad Dog_2

Never saw a code on that..as Johnny NY said, go for it. When I get above 2" I go with a flanged union. Mad Dog

Bostoner

thanks guys!!! My plumber has changed his tune and will install unions. I told him I had talked to "a bunch of plumbers" who thought it was fine.

EBEBRATT-Ed

I'll give your plumber credit for remembering what the gas code says. It just doesn't apply in this case. At least he actually reads code books and remembered something about a concealed union was looking to do the right thing.

jonny88

you know its weird, in the city we never used unions on gas until after a gas cock eg boiler etc. always a left to right nipple and coupling,then move out to long island and they are allowed to use unions as long as not concealed .Old habits die hard I rather a left to right.

EBEBRATT-Ed

Well, unions can be leakers that's for sure so the fewer the better. I have sometimes used 300# unions or "Dart" unions if I really couldn't have a leak especially on gas. 2 1/2 and up flanges are better.

j a_2

Red flag warning up....If in fact he is a plumber that is just plain stupid....plumbing code does not cover steam piping...Plumbing code does not cover gas work...Mass and all of mass. Works under NFPA 54 2012....Gas unions were allowed in walls when staked...under last book NFPA 542002 we changed a few months ago...So I will reconfirm..and respond... Left to right fittings available at economy plumbing in Dorchester...good for steam, air but not for gas... Any lic. plumber in mass. Should know this....Caution if not
..

Charlie from wmass

I was going to say unions are allowed, but if they are in a wall they need to be punched to prevent accidental loosening.

j a_2

Charlie that's correct, and staked is just another word for punched.....I have not had reason to look at new code..is it still in there....

Charlie from wmass

Still there. Went over it in continuing education last time.

j a_2

Thanks. Good to know.

ChrisJ

Curious how a union get's "accidentally loosened" inside a wall on a gas pipe?

The unions on all of my steam radiators and steam piping don't even seem to become loose and those heat and cool constantly.

What gives?

Do people go around periodically and torque their unions?

ChrisJ

j a said:

Red flag warning up....If in fact he is a plumber that is just plain stupid....plumbing code does not cover steam piping...Plumbing code does not cover gas work...Mass and all of mass. Works under NFPA 54 2012....Gas unions were allowed in walls when staked...under last book NFPA 542002 we changed a few months ago...So I will reconfirm..and respond... Left to right fittings available at economy plumbing in Dorchester...good for steam, air but not for gas... Any lic. plumber in mass. Should know this....Caution if not

..

My plumbing code book says no unions or bushings in concealed locations.

j a_2

Well Ias I said before it depends on the book and laws governing your particular area....My opinoin ,if I had other options I would not use a concealed union..but I have and never had an issue....

ChrisJ

j a said:

Well Ias I said before it depends on the book and laws governing your particular area....My opinoin ,if I had other options I would not use a concealed union..but I have and never had an issue....

Of course,
But what's with the "accidental loosening" Both you and Charlie said it so I know it's real. What causes it?

j a_2

Not so sure I would have said that....how would they lossen especially if staked?

ChrisJ

j a said:

Not so sure I would have said that....how would they lossen especially if staked?

That was your reasoning for "staking" them. If they don't get loosened with access, how would they get loosened when concealed?

j a_2

Reason is simple. Gas code calls for it..as for steam its fitters choice...

j a_2

We in Mass. have 3 main codes...plumbing code, That also contains mandated changes to the existing gas code, we have the gas code,and the mechanical code that is becoming very popular,...then there is always the common sense code...We also until age 65 must attend continuing education once a year...just too keep us informed of any changes..The state board meets monthly and is open to the public, that encourage questions and comments.. It is a very professional group..I know it must seem like a bit of overkill to some out of staters, but it is what it is...our choice...

nicholas bonham-carter

I think Chris wanted to know the real principles behind the possible dangers of using unions in an enclosed area, and not just the Mommy says so of the code.
Understanding the physical principles behind what is done, should be even more important than knowing the code.
I am going to guess that if the building were to settle, then the resulting movement of a gas pipe could misalign a union, causing it to leak, and that staking might not be enough.--NBC

Charlie from wmass

If a person works on the gas pipe, or any pipe it puts pressure on the pipe. Say a person wants to change a fixture and they pull out the stove and twist the riser they can loosen the union unless you punch it.

Charlie from wmass

Gas doesn't tend to rust things together like steam or water does so even an 80 year old fitting can come loose with minimal effort.

j a_2

I think its a job by job decision based on the situation at hand.Charlie you know two pipe wrenches are a no brainer... Hold back every pipe....and fitting...Do your gas test and be done with it... Use of unions in a wall without accessibility would be my last choice,even thou its allowed by law...More worrisome to me is unions inside a gas boiler jacket,I saw it all the time....When you go into a unknown job for service and see all the crap out there, its hard to explain to the poor customers its really not correct...So what I used to do is put it in writing and give them the report...If unsafe and they did not want to correct the best thing to do is an about face. See ya later

ChrisJ

j a said:

I think its a job by job decision based on the situation at hand.Charlie you know two pipe wrenches are a no brainer... Hold back every pipe....and fitting...Do your gas test and be done with it... Use of unions in a wall without accessibility would be my last choice,even thou its allowed by law...More worrisome to me is unions inside a gas boiler jacket,I saw it all the time....When you go into a unknown job for service and see all the crap out there, its hard to explain to the poor customers its really not correct...So what I used to do is put it in writing and give them the report...If unsafe and they did not want to correct the best thing to do is an about face. See ya later

That's odd,
I just put a union inside my boiler jacket so the burner tray can be easily removed for service or cleaning. It's also allowed by code here.


Why is that so scary to you? It can be tightened properly and leak tested just as any other union can.

j a_2

Well I would say we have a different opinion...... That's all....I guess after 35 years installing
Boilers I am set on my ways....Is installing unions a standard practice for your plumbing business?

ChrisJ

j a said:

Well I would say we have a different opinion...... That's all....I guess after 35 years installing
Boilers I am set on my ways....Is installing unions a standard practice for your plumbing business?

Please don't attack me for being a homeowner when it's not relevant to the discussion. Many boilers have a union inside the jacket, just because mine wasn't supplied with it from the manufacturer doesn't make it unsafe. Further more it's code compliant.

If you have a reason to believe it's unsafe then please explain, otherwise my profession has nothing to do with this.

I believe @KC_Jones also has a union in his. Without it, it's a nightmare to pull the burner out to clean or service it. Same goes for replacing the CGV.

j a_2

Not here to teach the code....what home owners do is there own business..Its just me being me...best of luck

j a_2

Let me say this, over my time and a lot was a sub contractor for the gss copany...I found very few couplings leaking,but quite a get unions...T install manuals for most of the big name boilers show a typical gas train drawing...
Never ever saw one with a union...supplied..
Also manufacturs reguire a min. distance clearance for service work....How pray tell it is a nitemere to pull a gas manifold it

jonny88

In my opinion if union is installed after gas valve there is no issue in taking pipe apart.Unions make me nervous inside boiler jacket.I had a whole house re pipe on monday as they added a gas appliance.Here as long as unions are visible its ok on gas.Well when I put test on gas line 3 unions were leaking along with other parts of piping.Inspection was on Tuesday not my call.I wasnt going to cut left to rights in everywhere.Unions have there place but I think as a pipefitter we should know better and where and when to use them.

ChrisJ

j a said:

Let me say this, over my time and a lot was a sub contractor for the gss copany...I found very few couplings leaking,but quite a get unions...T install manuals for most of the big name boilers show a typical gas train drawing...

Never ever saw one with a union...supplied..

Also manufacturs reguire a min. distance clearance for service work....How pray tell it is a nitemere to pull a gas manifold it

Perhaps nightmare is the wrong term, it's more a pain in the butt because I need to pull apart several lengths of pipe to remove the nipple going into the CGV.


I find it amazing someone installed unions that leaked at 6 or 7" WC. That's pretty sad. Chinese parts? Mating surfaces scratched or dirty? Not torqued properly? I just installed a Ward union on an air line that doesn't leak at 130 PSI. But what do I know, I'm just a dumb homeowner, right?

What is so different between next to the boiler, and in it's vented vestibule? It's not hidden and it's 100% accessible. I still have not had an answer on this, though I keep asking.


@KC_Jones You pulling your union out of the boiler? It seems to creep a few people out for some unknown reason.

KC_Jones

ChrisJ said:

@KC_Jones You pulling your union out of the boiler? It seems to creep a few people out for some unknown reason.

Nope it's staying right were it is, no leaking issues or worries.

Charlie from wmass

if it leaks it's closer to the point of combustion. The gases can build up inside the cover and go boom. The union could be left loose and the gas turned on with the union out of sight.

ChrisJ

Charlie from wmass said:

if it leaks it's closer to the point of combustion. The gases can build up inside the cover and go boom. The union could be left loose and the gas turned on with the union out of sight.

Thank you Charlie.

j a_2

Just not standard practice in gas work. That's all I am saying....if you feel good about it that's great

ChrisJ

j a said:

Just not standard practice in gas work. That's all I am saying....if you feel good about it that's great

I get that, I wanted to know why.

Charlie explained it.

ChrisJ

Hatterasguy said:

ChrisJ said:

Same goes for replacing the CGV.

If the union is outside the cabinet between the CGV and the ball valve, does this not accomplish the same thing?

You'd need to remove the CGV to change the burner but that task isn't onerous.

The ECR has the CGV outside the cabinet which makes changing it a snap.

It would make it a lot easier, but you'd still need to remove the nipple from the CGV to slide the burner out where in this case all you do is loosen the union. I don't know about others, but if I have to clean the burner I don't have time to waste, I need to get in there and get it done.

Also, I don't have room in that specific location for a union, but that's another story and there are ways to fix that.


As far as I'm concerned the chances of that union leaking are the same as every other joint located in that area. Just as any threaded joint it should be leak tested after being assembled.

ChrisJ

And I'm going to be blatantly honest here, if someone put three unions together and all three leaked at 7" WC or even 15 PSI, they shouldn't be working on gas piping.