Hanger Rods

[NightME]

NFPA 13 (2007) para. 9.1.2.6 states: "Threaded sections of rods shall be be formed or bent."

Is this sentence telling me that all my threaded rod must be, essentially, perpendicular to the floor?

I have been inspected a project and the AHJ has performed their own inspection and have stated that all threaded rod must be "completely verticle."

This installation is not sloppy or "bad" however the AHJ is stating that it will not be accepted until all hangers are absolutely verticle.

Any thoughts?

 

[stookeyfpe]

Section 9.1.2.6 in my 2007 edition of NFPA 13 states Threaded sections of rods shall not be formed or bent. I read it as saying you can't used a bent or formed (i.e., pressed or forged) ATR. I completely understand why this is not allowed because any bends or forming reduces the root thread diameter of the rod, which in turn reduces is yield strength.

So long as the root thread diameter has not been compromised, then NFPA 13 is satisfied. If the ATR is bent, then the AHJ should not accept the hanger installation.

 

[TravisMack]

In my experience, the rod must be straight, but that does not mean perpendicular to the floor.

As Stookey stated, you can not bend ATR. If you must bend the rod, you can't use ATR. I have had to use bent rod on some installations. It is a real pain.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[NightME]

The hangers are not "bent" only slightly bowed...slightly being the key word.

This metal building (similar to a Butler building) has purlins that are angled to about 15-20 degrees and over the span of 10-15 feet of rod the bow is only minor.

It is my belief that since the rods are not bent, torqued, or anything else that would obviously affect their load capacity that this minor bow is acceptable.

The annex of 13 does describe the "shoulds" of the installation, but the body does not (except for the bent or formed). I am just curious what the concensus is?

Thanks

 

[ryano669]

Tolco makes a nice swivel fitting to use in these applications. See the link below.

 

[ryano669]

Also one made by Sammy. This one is more applicable to purlin installations.

 

[SprinklerDesigner2]

Bent metal purlins.

Most attachments are fine, they're UL Listed and Factory Mutual Approved but what about the building manufacturer?

Butler has sprinkler pipe hanging guidelines for their buildings and if I remember right (it's been a while) you got a real problem hanging any size line from the bottom of the purlin. You do this and Butler has in their fine print the building warranty is void.

You hang 4" from the bottom of a purlin and I know Butler's engineers will have a fit. I've never known them to bring it up but the moment there's a warranty problem I suspect they'll walk away.

I drill a hole through the vertical member of the purlin a third way down from the top then secure an eye rod using a 3/8"x1" bolt, two washers and nut. Cordless step drills make quick work of it so time shouldn't be a problem.

Always check with the building manufacturer getting their recommendations in writing if possible.

My two cents.

 

[SprinklerDesigner2]

Found it, Butler's hanger requirements. Might be eye opening for some.

http://www.mybuildernet.com/sedd/Erection/80/1081464.pdf

Given this how do you hang any pipe >4" from a purlin?