NFPA 13 (2016 Edition) Section 9.2.1.4.1 states:
9.2.1.4.1 Branch line hangers attached to metal deck shall be permitted only for the support of pipe 1 inch of smaller in size, by drilling or punching the vertical portion of the metal deck and using through bolts. The Sammy X-Press has listed hangers that call out attachment directly to metal deck for pipe up through 4" in some cases. From a code perspective, does the section above not apply, or would this be a code approved alternative? Just looking for the code logic that would allow use of listed special materials where the section above wouldn't trump this method. Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe
7 Comments
Wayne Ammons
10/9/2019 08:39:22 am
Products specifically LISTED for use on fire sprinkler systems are allowed by NFPA 13. Below is commentary from the 2016 edition of the NFPA 13 Handbook on this particular subject:
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Skyler
10/9/2019 12:03:38 pm
The commentary hits it on the head. It all depends on the thickness of the deck, but NFPA 13 basically says that for 1" it doesn't matter. Composite metal decks typically range from 16 to 22 gauge, with 18 and 20 being the most typical. Metal roofs on a pre-engineered purlin structure tend to be 22 or 24 gauge. Purlin thicknesses can range wildly, but they are one of the best use cases for the Sammys you referred to.
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J. Wilson
10/9/2019 10:26:49 am
The point is that if it listed by manufacturer it is acceptable. Follow all manufacturer instruction your good.
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Skyler
10/9/2019 12:11:21 pm
Just noticed the actual question you posed. I would refer you to the section in the beginning of the hanging chapter (9.1.1.2) that allows an Engineer to use alternative hanging methods and lists the criteria. This is very useful for non typical situations. Since you are an Engineer, I would say you can use this section to justify the use of the Sammys you referred to (just pay close attention to the metal thickness you are attaching to).
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Wayne Ammons
10/9/2019 01:57:01 pm
Skyler,
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On the Clock
10/9/2019 03:34:28 pm
I agree 100% with Wayne's comments above. Note that the building structure also must be capable of supporting the load as described in NFPA #13 (2016) 9.2.1.3.1. When they first came out (and before I knew better), I was guilty of overly-liberal use of Sammy XP's. I offer this as a caution, on my projects, the structural engineer-of-record routinely prohibits, or greatly limits hanging directly to the metal deck, regardless of the gauge of the deck. And it can vary project-to-project.
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Wayne Ammons
10/9/2019 04:16:39 pm
Excellent point. Whenever we (my company) wish to hang directly to the metal decking, we always get approval from the structural engineer or GC, regardless of what we know about the steel gauge.
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