6" schedule 10 pipe in Wood Assemblies

[GlorifiedPlumber1984]

Does anyone have any tips on hanging pipe larger than 4" from a wood truss? Sammy (coach screw rods) are only allowed for 4" and under, and this is new for us. I was thinking about using trapeze assemblies, with 2 1/2" pipe as the modulus. I'm not sure if doing that would allow each point of the 2 1/2" pipe to then be allowed to use sammy screws as the sammy is then supporting 2 1/2" pipe instead of 6", but I'm just not sure on it. Hanging methods of large pipe in wood framing seem few and far between.

 

[SprinklerDesigner2]

We always used a 1/2" coach screw rod.

[URL unfurl="true"]https://phd-mfg.com/wp-content/uploads/2018/06/40_5-25-18.pdf[/url]

 

[GlorifiedPlumber1984]

The AHJ is pretty by the book, and 2016e of NFPA 13, 9.1.5.7.1 looks like larger than 4" is not permitted. The biggest problem is the truss's are made with 2 x 4, so not a lot to work with.

 

[UFT12]

If the AHJ goes by the book, show them 9.1.1.2. It is a simple process to calculate the modulus required for a trapeze member to support the 6" pipe. By the way, the trapeze hangers will support neither 6" or 2-1/2" rather both. Points of attachment on the wood frame could be two or more for extra safety and depending on actual situation. Have a licensed engineered to sign that off if necessary.

 

[skdesigner]

You would use a side beam bracket like a Tolco Fig. 51 (

https://www.vikinggroupinc.com/sites/default/files/usrelated/tolco/fig51.pdf).

But that would be to hang from a fairly substantial wood beam. The structural engineer might have a few things to say when he finds out you plan on stringing 6" from trusses made from 2x4's.

 

[MGXFP]

You'll could split the flow into two 4" pipes instead of one 6" pipe in order to hang it from the available structure. Two 4" pipes will give you 28.5 sq.in. of area vs. 31.7 sq.in. of a single 6". That would have slightly higher friction losses but you can install it.