Which Test Weight to Use for Hanger Spacing?

4/30/2020

Many listed hanger fasteners have their own weight limits. When I calculate the allowable hanger spacing for different size pipes, should I be using the Ultimate Pullout, UL Test Load, or FM Test Load?

Just looking at the Sammys for Wood Vertical (https://www.swfastener.com/pdf/ITW%20Sammy.pdf), for instance - some of the wood screws can have three different load values and I'm not entirely sure which I should be using to determine the appropriate hanger spacing for a sprinkler system. Thanks in advance.

Posted anonymously for discussion. Discuss This | Submit Your Question | Subscribe

3 Comments

Dan Wilder

4/30/2020 08:21:13 am

For the same MFG, please look at the more current catalog, which on Page 14 shows the listings for both UL & FM in a maximum pipe size available. Typically, anything with fire sprinkler listings or approvals are shown with a maximum pipe size but you may need to reference this based on the UL listing or FM approval sheet if the MFG data sheet does not specify. ICC-ES sheets are also very helpful with exactly how items are to be installed and in what conditions.

http://www.itwbuildex.com/pdf/updated_sammys_catalog_2018_19.pdf

For example, Caddy Top Beam Clamp indicates 2 loads and shows a UL listing and FM approval for the 3/8" & 1/2" models but no pipe sizes.

https://www.erico.com/catalog/categories/R385?pdf=1&language=en&country=US

However, digging into the general page you can get to this page which links out to both UL (Free account required) & FM and these show maximum pipe sizing for the 3/8" up to 4" and the 1/2" up to 8"

https://www.erico.com/category.asp?category=R385#catalog-documents

https://www.erico.com/catalog/certifications/FM.pdf

Most websites are setup this way and generally speaking, if the 3/8" version is UL & FM, it can handle piping up to 4", the 1/2" models can hold up to 8".

This next part is a whole 'nother Q/A itself but in a nutshell...

There are exceptions, the most notable that comes to mind being the Hilti HDI-P which shows UL/FM BUT this is based on applications using "Uncracked Concrete". I have not been on a project yet that I could get a structural engineer to sign off that the PT slab was "Uncracked Concrete" (Hilti lost their listing on this product back in ~2006 for a bit because of the cracked vs uncracked designation hence the ICC-ES came into the spotlight). However, Hilti also makes a HDI-P-TZ version that is allowed for cracked concrete and for use in seismic areas for shallow enbedment applications up to 4".

In the end, just read through the available literature on the sites if you don't see pipe size limitations in fire sprinkler applications.

Casey Milhorn

4/30/2020 10:19:58 am

I think you are asking what number to use when comparing to the weight of the water filled pipe x 4 + 250 lbs (Per NFPA 13). If that's the question, then go by the UL listing (if its a UL job), FM listing (if its a FM job), or your choice if the job doesn't have a specific listing agency in the specs. So for example, if your weight of your pipe + 250 lbs equals 350 lbs at a 10' spacing, and your UL listed test load is 360 lbs, then you are in good shape. Rarely have I ever seen an issue with the listed pullouts not being enough to space hangers to 12' or 15' per NFPA 13. But it is worth checking for when dealing with a new hanger attachment or larger pipe.

Mike

5/5/2020 10:30:47 am

In the appendix it states the 250# is a safety factor.

I don't think it should be included in the design load if applying them to a load limit for a particular structure. Instead, consult with the structural engineer to see if their safety factor accommodates the additional 250#.

Has anyone else taken this route?

Free Signup

Subscribe and learn something new each day:

Community

Thank You to Our Top
August 2020 Contributors!

1. SK
2. Near Engineer
3. NinaB
4. Brenton
5. Mike

6. Sean
7. Dan Wilder
8. Tim D.
9. Rob B.
10. Jonathan

Your Post

SUBMIT A QUESTION

The Toolkit

Sprinkler Designer or Engineer?

Get all of our tools, including the Sprinkler Database, Friction Loss Calculator, Fire Pump Analyzer and more:

FREE 30-DAY TRIAL

GET THE TOOLKIT

Filters

Exam Prep

2020 PE Prep Guide
(Available Now!)

PE Prep Series
(Available Now!)

2020 PE Prep Series
Current Leaderboard
(Click to enlarge)

PE Problems

Visit July-October for daily Fire Protection PE Exam sample questions.

Solutions are posted the day after posting.

Comment with your solutions, questions or clarifications.

Please note that questions posted are unofficial and in accordance with NCEES rules are intended to be similar to actual exam questions, not actual exam questions themselves.

RSS Feed

Home - About - Blog - Contact - Exam Prep - Store

Copyright © 2020 MeyerFire, LLC
The views, opinions, and information found on this site represent solely the author shown and do not represent the opinions of any other party, nor does the presented material assume responsibility for its use. Fire protection and life safety systems constitute a critical component for public health and safety and you should consult with a licensed professional for proper design and code adherence. Some (not all) outbound links on this website, such as Amazon links, are affiliate-based where we receive a commission for orders placed elsewhere.