Clearance Req'd Between Steel & Sprinkler Pipe?

2/22/2024

Is there a minimum clearance requirement in NFPA 13 between structural steel and steel sprinkler pipe?

Area is not subject to earthquakes and the structural engineer want to strap the pipe directly to the steel like CPVC is strapped to wood.

I've always been of the understanding that steel pipe must be hung, strapped to Unistrut attached to the structure, or supported on a trapeze, but I can't find where in 13 (if it exists) that says I can't use a strap.

Obviously the fittings/couplings will prevent the pipe itself from contacting the steel. Trying to get the pipes as tight as possible to the sloped structural members and even using 1-5/8" unistrut with pipe clamps is getting pushback.

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8 Comments

Pete H

2/22/2024 07:41:37 am

No required clearance as far as I know between steel and sprinkler pipe.

Don't drill through steel without talking to a structural engineer.

There are required clearances between sprinkler deflectors and steel. Those depend on construction type and sprinkler head.

Could be entirely wrong, I did not look into this.

Dan Wilder

2/22/2024 08:02:22 am

If there are no seismic considerations, technically no.

Not sure I have heard of an approved hanger (strap) for this application...I've used "Mutt & Jeff", "U", and wrap around "U" hangers for wood applications (Tolco 120, 120MJ, 120W) along with the more standard "U-Bolt" hanger (Tolco B3188) with top beam clamps to attach to I-Beams.

James Art, FPE

2/28/2024 11:53:59 am

Mutt and Jeff means a couple of things:
For U hooks, it can be where the lengths of the 'arms' are different,
such as hanging from wood on a slope.
But for tieing togther a pipe like around a Vic Groovelock,
or equivalent,
It can mean two all thread rods tieing to two "riser clamps", one long rod and one short rod to only one of the clamps each, so the clamps bind.
Does anyone have a good picture of this?
THANKS!

Jim

Glenn Berger

2/22/2024 08:13:12 am

Clearances between sprinklers and obstructions are covered in NFPA 13. Clearances between piping and structural members are not specifically stated.

Anthony

2/22/2024 08:15:20 am

there is no requirement. I've designed systems that require the pipe to be "strapped" to the bottom of beams for spacing concerns.

I'd also add you can core through the center of an I beam and rest the pipe there as a hanging point. note you'll need structural approval.

Michael

2/26/2024 11:12:41 am

In this case I would recommend some type of neoprene pad or similar between the pipe and steel.

Dave

2/22/2024 11:32:48 am

Clearance requirements are partly based on whether or not the piping will move independently from the structure. For horizontal piping, NFPA 13 requires 2 inches clearance from structural members which are "not penetrated or used, collectively or independently, to support the piping"
(18.4.9 in the 2019 Edition)

RYAN HINSON

2/22/2024 01:01:39 pm

It should be noted that NFPA 13 (2019) Section 18.4.9 only applies where seismic protection is required. The original post indicates that this is not the case.

I would note that common sense should direct one to provide sufficient clear space all around piping for pipe wrench- or coupling dis/assembly.

If strapped directly to beams, minimum bolting component sizing must be met or the assembly "...has been tested and listed by a testing laboratory and installed within the limits of pipe sizes expressed in individual listings" per Section 17.2.

Additionally, spacing between such supports must still adhere to Section 17.4.2.

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Clearance Req'd Between Steel & Sprinkler Pipe?

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