1-1/4" residential gas line - potentially stressed

[Rossn]

As part of rebuilding my home, some 1-1/4" black iron for natural gas was run to the utility room. It was run in the middle 1/3 of the 2x8 joists and is a pretty tight fit (see below). It's not possible to remove or re-insert new rigid pipe at this juncture.

The gas line runs parallel and close to a 18' engineered steel beam that supports the upstairs floor joists.

I am putting in new subfloor upstairs currently and, no doubt, there is sometimes some deflection on the beam, and we will be adding a lot more load.

Before I cover the beam with subfloor, I'd like to understand the level of concern about loading the gas line. I am assuming black iron will not flex, but would be great to hear from the experts.

At L/360, we'd see around 0.6" deflection, and I will check with the engineer what it was actually designed to.

Secondary to this, if it is determined as a safety issue, are there any more flexible products allowed in residential that could be patched into the section passing parallel to the beam (or flex joints, etc)?

Thanks in advance!

 

[John Gayewski]

The joints like a coupling near the center might be a concern but 3/16" flex is perfectly fine.

If the engineer says otherwise or has another opinion you could abandon it and replace it with csst. We use gastite.

 

[Sponsor]

 

[Jeff H Young]

If the beam sags 3/16 or 5/8 or .6 inches I dont see that as problem. Or where the concern arised as whoever told you to explain it. Im neither a structural engineer nor even a carpenter but a Plumber.

 

[Rossn]

The joints like a coupling near the center might be a concern but 3/16" flex is perfectly fine.

If the engineer says otherwise or has another opinion you could abandon it and replace it with csst. We use gastite.

Thanks, John. I really didn't have a clue if it would flex at all, as black iron has always seemed extremely rigid to me. I'm thankful to have black iron instead of the alternative, as a framer tried to put a framing nail through it with a nail gun from the subfloor above, and the nail just furled up.

Thanks for confirming there is an alternative that could be used. It looks like the OD is at or slightly smaller than black iron, which is good. I can press forward with the subfloor without worrying about access from above.

Unfortunately, there is actually a 1 1/4 - 1 1/4 - 3/4 tee near mid-span. That is what got me thinking about this, given the upcoming increase in load on the floor and how tight the black iron is already.

For my back pocket... With the black iron in-place, is it workable to cut out a section for a joist bay (or two or three) and fit a small section of csst in-place? I'm not sure what transitions look like between CSST and black iron, and if that can be attached to unthreaded black iron?

I will get with the engineer shortly and see his thoughts on the deflection.

 

[Rossn]

If the beam sags 3/16 or 5/8 or .6 inches I dont see that as problem. Or where the concern arised as whoever told you to explain it. Im neither a structural engineer nor even a carpenter but a Plumber.

Thanks, Jeff. The concern arose because I am experiencing more deflection in the beam than I would have expected... in conjunction with the fact that post remodel, we are loading the joists with probably 4000-5000lbs more than they saw originally.

And... that there is a fitting near the center (location of max stress).

I'll check in with the structural engineer.

Edit: I should add that this is an engineered steel beam, which has a 18' span.

 

[John Gayewski]

Thanks, John. I really didn't have a clue if it would flex at all, as black iron has always seemed extremely rigid to me. I'm thankful to have black iron instead of the alternative, as a framer tried to put a framing nail through it with a nail gun from the subfloor above, and the nail just furled up.

Thanks for confirming there is an alternative that could be used. It looks like the OD is at or slightly smaller than black iron, which is good. I can press forward with the subfloor without worrying about access from above.

Unfortunately, there is actually a 1 1/4 - 1 1/4 - 3/4 tee near mid-span. That is what got me thinking about this, given the upcoming increase in load on the floor and how tight the black iron is already.

For my back pocket... With the black iron in-place, is it workable to cut out a section for a joist bay (or two or three) and fit a small section of csst in-place? I'm not sure what transitions look like between CSST and black iron, and if that can be attached to unthreaded black iron?

I will get with the engineer shortly and see his thoughts on the deflection.

You can do that but it needs to be accessible and it looks kind of junky. Another thing to think about is csst can't convey the same amount of gas at the same pressure that bmi can. So if your load is tight csst might need up sized.

 

[wwhitney]

Thanks, John. I really didn't have a clue if it would flex at all, as black iron has always seemed extremely rigid to me. I'm thankful to have black iron instead of the alternative, as a framer tried to put a framing nail through it with a nail gun from the subfloor above, and the nail just furled up.

How'd that happen, were they shooting 3" nails or longer nails? Any hole in the joist needs to be at least 2" clear from the edge, and the subfloor is generally at least 3/4" thick, so that's 2-3/4" right there.

Cheers, Wayne

 

[Tuttles Revenge]

For my back pocket... With the black iron in-place, is it workable to cut out a section for a joist bay (or two or three) and fit a small section of csst in-place? I'm not sure what transitions look like between CSST and black iron, and if that can be attached to unthreaded black iron?

I will get with the engineer shortly and see his thoughts on the deflection.

Megapress threaded adapter to CSST autoflare would be the easiest way to splice in the middle...

 

[Rossn]

How'd that happen, were they shooting 3" nails or longer nails? Any hole in the joist needs to be at least 2" clear from the edge, and the subfloor is generally at least 3/4" thick, so that's 2-3/4" right there.

Cheers, Wayne

Hey Wayne!

Yeah, good question... 1-1/8" subfloor, and that section of black iron is a branch going outside for grill and generator. It is only 1" below the bottom of the subfloor *, and while I haven't checked - I assumes this needs a nail plate (which wouldn't stop a framing nailer... I will probably put a strip of at least 1/8" steel above it, but am glad to hear recommendations.

See pics, below.

You would *think* when laying down subfloor over a bunch of plumbing, you'd know where it is (visible right before putting the sheet down) and notice things like gas lines. But you'd also think they wouldn't be hitting between joists... I'll be replacing that section of black iron when the valve gets added downstream.

And, no idea what happened with that nail coming close to the not-yet-in-service copper. They must have fired between sheets or before one was down?

On top of that, the new subfloor they put down in that area is out by 7/8" of an inch, so makes for a good challenge putting in the subfloor in the adjoining room. Not very happy with the framing crew!

I'm sure you all will enjoy these photos as plumbing horror.

Can you guess which nail hit it, dead on?

* Edit to correct top of joist -> bottom of subfloor

 

[Rossn]

Megapress threaded adapter to CSST autoflare would be the easiest way to splice in the middle...

Ok, thanks... great to know they make an adapter - I haven't checked into megapress in any detail, and think my RP240 only handles smaller sizes . However, there is a place locally that rents them, and I think my radiant guy may also have one large enough.

At least I know what a backup plan will be, if the engineer has concerns.

Anyone know a creative technique for cleanly enlarging a hole in a joist that is almost packed out? Maybe that is a separate thread.

 

[Rossn]

You can do that but it needs to be accessible and it looks kind of junky. Another thing to think about is csst can't convey the same amount of gas at the same pressure that bmi can. So if your load is tight csst might need up sized.

Ok, good to know all these things. Accessible... I guess it could be if I do the full 18' run... there is a storage room where the 1-1/4" runs, with the other end in the laundry/utility room.

Is the access due to the fitting or in particular a transition?

Luckily we are already oversized a fair bit for some potential future use, but will check into sizing in detail if the engineer thinks we need to do something.

 

[Chefwong]

Post #9 Rossan.
That would easily warrant inspecting every hole where every pipe is IMO.....

 

[wwhitney]

Yeah, good question... 1-1/8" subfloor, and that section of black iron is a branch going outside for grill and generator. It is only 1" below the top of the joist

If the hole in the joist is only 1" from the top edge of the joist, then that hole violates the prescriptive allowances in the IRC. That joist should get a repair/reinforcement, maybe a properly sized metal reinforcement along the top edge.

https://up.codes/viewer/colorado/irc-2021/chapter/5/floors#R502.8

In practice if it's just one joist it probably won't make a difference, but those are the rules.

Cheers, Wayne

 

[Rossn]

Post #9 Rossan.
That would easily warrant inspecting every hole where every pipe is IMO.....

Yes, I agree, and will. I think at one point I slipped some plastic into the top to see if any obstruction, but will go back and verify.

 

[Rossn]

If the hole in the joist is only 1" from the top edge of the joist, then that hole violates the prescriptive allowances in the IRC. That joist should get a repair/reinforcement, maybe a properly sized metal reinforcement along the top edge.

https://up.codes/viewer/colorado/irc-2021/chapter/5/floors#R502.8

In practice if it's just one joist it probably won't make a difference, but those are the rules.

Cheers, Wayne

I don't think I communicated well... see the pics. The 1" is a branch where it is running parallel to the joist bay and rises up from the trunk, so it is closer to the subfloor.

All the bored holes are within the IRC limits, though it seems a bit crazy to have that many penetrations, which is why we added the LVL joist stiffeners.

I'll correct my post... said joist and meant subfloor.

 

[Chefwong]

rossn. Years ago, was having some construction done. Me being OCD, I would get home from work.....and I backed the screws out to see inspect. Screw was holding water in the copper....and the minute I removed it.....well, you get the point.

Hopefully you catch any opposes.

Hopefully, nails were not backed up - pulled out, and you might have a pipe that has been -damaged- but not aware due to said nail being backed out.

 

[Rossn]

rossn. Years ago, was having some construction done. Me being OCD, I would get home from work.....and I backed the screws out to see inspect. Screw was holding water in the copper....and the minute I removed it.....well, you get the point.

Hopefully you catch any opposes.

Hopefully, nails were not backed up - pulled out, and you might have a pipe that has been -damaged- but not aware due to said nail being backed out.

That sounds very time consuming!

Those copper lines aren't pressurized yet. I think I slid the various plumbing (except gas) back and forth a little to ensure they could move, meaning no punctures.

 

[Chefwong]

Water would be easy to spot. I would pressure test the gas tho.....ur pic literally speaks volumes IMO

 

[Jeff H Young]

I dont think those are regular joists look like LVL and come under differant manufacture spec.

 

[Rossn]

I dont think those are regular joists look like LVL and come under differant manufacture spec.

While LVL joists would be under specific requirements for boring, this LVL is acting as a stiffener sistered to the original older joists. The engineer OK'd boring it, and said it is not subject to code, since it's not the actual joist (rather, a stiffener). So, we're fine.