Branch Pipe Always Perpendicular to Structure?

12/28/2020

Are there ever scenarios where fire sprinkler branch pipe would not be perpendicular to structure?

As I understand it, running perpendicular to structure affords installers the most flexibility in hanging locations and avoids having to use trapeze supports throughout a project where support from the floor/roof assembly isn't possible.

Just curious if branch pipe perpendicular to structure is an always scenario or just a prevailing scenario. Thanks in advance, appreciate your all's input.

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5 Comments

Mike

12/28/2020 09:06:10 am

Depends if you have a concrete roof or floor deck above. Too many different possibilities to give you a definitive answer.

FIREPE25

12/28/2020 09:19:35 am

It all depends. If the deck is concrete then the pipe can be run in any direction due to ease of hanging in concrete. If the deck is metal and sammy express are permitted into the metal deck the pipe can also be run in any direction. Otherwise trapeze hangers would be required, which are a LOT more work.

Generally it is much smarter to run line piping perpindicular to the steel.

Dan Wilder link

12/28/2020 09:36:18 am

Nothing is "written" as to branch lines running perpendicular to structure, it is both more economical and easier to install them this way.

As you stated, there are many more ways to support the BL's when running perpendicular vs parallel. In the case of open web scenarios, the field can "stuff" the BL's into the spaces then hang vs bringing up and hanging each piece individually. In the case of obstructed construction, placing the line parallel can force a smaller BL spacing (every 7.5-8') due to solid members.

There are more BL's than mains on a system so if their is a need to require trapezing, doing it on the main is cheaper.

Obstructions become an issue. A design can be completed without any need to have the truss calc files (paperwork showing the webbing members) going perpendicular just based on the spacing. Run BL's parallel (without trapeze) and the webbing members become a much greater impact especially as the hazard increases.

Yes, there are some scenarios where running parallel with the structure has been done. A large butler style building with sidewalls (technically, this is still perpendicular but the lines are hung from the I-beams vs the C-Channel). I have done butler buildings where the owner wanted the piping hidden in the C-Channel (https://bit.ly/3hnBRAM). Parking garages with BL's in the double tee spaces using pendents is another.

Aria Casino has a large skylight feature upon entry that was run parallel with the structure for two systems to hide the lines within the soffiting and the check-in desk (mush smaller area) also was designed to hide the piping.

The Bellagio Flower Garden area is another place I can think of that ran the piping with the structure.

Glenn Berger

12/28/2020 09:50:39 am

Another application is one where there is a minimum headroom to be maintained above the floor. This is a gotcha moment to many Contractors.

12/29/2020 12:07:53 pm

i had a situation where the lenght of the purlin was greater that he dimension required from the sprinkler deflector to the ceiling (it was exceeding an inch or so) so we had to project the BL's pararell to the secondary structure.

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