The structure needs to support a larger point load (with a very complex explanation, it probably does). Otherwise, if a guy working on the roof were to stand on one foot, the structure could potentially collapse. Structural engineering calculations are extremely complex (I would say more so than our hydraulic calculations).
The answer I can give that would be most helpful: I have had a similar situation on a project. Because of the complexities of structural engineering, I let the structural engineer deal with it (as they should, by law). I sent over our drawings, showing piping layout, hanger locations, with a table of pipe weight per foot, and section 9.1.1.2 (a), nice and big on the drawing (five times the weight of the water-filled pipe plus 250 lbs at each point of attachment). In the email I sent, I asked nicely how they would like us to hang it. Oftentimes, the structural engineer will come right back and say it will work. I have also had them come back and require the mains to be trapezed, or supported by primary members (girders, not trusses). Sometimes they will send the lovely note/detail we see on all Wal-Mart jobs about hangers being at/near panel points of the bar joists, or send a detail describing hanger attachments to purlins. Commentary: I went to school for Structural Engineering (I don't practice, and I'm not a Structural Engineer). For my senior design project (about 10 years ago), I worked with a company that makes the metal connector plates that hold together wood trusses, along with the structural design software to design the trusses, and corresponding plate sizes. I brought up our rule about five times the weight of the water filled pipe plus 250 lbs in a meeting one time. The head engineer asked one of the other guys if they designed for this. The reply was a long way of saying no, and there would be plenty of cases where real truss designs would fail the calculations, if they took this into account. The head engineer let out an audible "Hm", and we moved on. In my later work with them, I learned that their designs (per ASCE 7) have a built in safety factor, such that the trusses can typically hold 2 to 3 times what they are designed for. This could help explain why it seems like such a large problem in the design phase of projects, and not *as much* of a problem in the real world (I imagine you could easily take down a structure if you hang some 12" main and turn the water on, without the structure being designed for it). There is a disconnect between how structures are designed and the point load described by NFPA 13. As Ken alluded to, our seismic bracing calculations vs. the actual structural design is probably a much larger disconnect. I'm sure there are other people that can detail this disconnect much better than I can (Ken), but I believe ASCE-7 takes our pipe/hangers into account as a uniform dead load, which is usually accounted for as part of a "miscellaneous load" or "mechanical system" dead load for all of the mechanical systems across the entire structure, which is expressed as some number of pounds per square foot. This 1 to 15 lbs/sq ft (or so) is usually a safe assumption, but it can often be an issue at mains, where the loads can be higher than what they have accounted for. I have also seen this being a larger load than the structural engineer expected (and designed for) in tall warehouses, where lines are 2-1/2" or 3". Long story short: from what little I know, structures are not designed the way most of us in the sprinkler world probably think they are. And somehow, this probably isn't an issue over 99.9% of the time. Again, this is complex, and not our job, so send it to the structural engineer, and let them deal with it. Just like my last post about asking the Architect to do their job. Now, if we could just get the other trades to install everything per plans (and/or Construction Management companies that *actually *coordinate things), life would be so much easier for all of us. Good luck, Skyler Bilbo Wente Plumbing and FIre Protection 1700 S. Raney Street Effingham, IL 62401 217-819-6404 Direct 217-347-7315 Fax [email protected] www.wenteplumbing.com **new** www.beplumb.com Like us on facebook <http://www.facebook.com/justbeplumb>for updates On Wed, Jun 3, 2020 at 11:41 AM Ron Greenman via Sprinklerforum < [email protected]> wrote: > And remember the building does not belong to you and it is NOT your > responsibility to come up with a solution. The owner, via his > representatives (the GC, the structural engineer, and ultimately, the > architect) is responsible for building a code-compliant building that > includes supporting any live or dead loads, including the sprinkler system. > And I'm guessing that in California insufficient point loading for hanging > would the least of your concerns regarding structure. > > > > Ron Greenman > > [email protected] > > 253.576.9700 > > The Universe is monstrously indifferent to the presence of man. -Werner > Herzog, screenwriter, film director, author, actor and opera > director (1942-) > > > On Wed, Jun 3, 2020 at 9:26 AM John Denhardt via Sprinklerforum < > [email protected]> wrote: > >> I agree with Ken. I have been down this road before. The structure needs >> to support the piping plus 250 pounds at the point of hanging. If the >> structure can handle this load, then the structure has an issue. >> >> Thanks, >> John >> >> John August Denhardt, PE >> *Vice President, Engineering and Technical Services* >> >> *American Fire Sprinkler Association* >> m: p: 301-343-1457 >> 214-349-5965 ext 121 >> w: firesprinkler.org >> <https://www.facebook.com/firesprinkler.org/> >> <https://twitter.com/afsa/status/1039528345367732224> >> <https://www.linkedin.com/company/american-fire-sprinkler-association-afsa-/> >> <https://www.instagram.com/firesprinklerorg/> >> >> *Help AFSA “Sound the Alarm” about sprinklers!* >> >> AFSA’s charitable partner the American Red Cross is educating millions >> through its Home Fire Preparedness Campaign. Help us support the inclusion >> of fire sprinklers in their messaging. Donate today! >> <https://www.redcross.org/donate/cm/afsa-pub.html/> >> >> >> On Wed, Jun 3, 2020 at 12:18 PM Parsley Consulting via Sprinklerforum < >> [email protected]> wrote: >> >>> Jerry, >>> >>> Although I'm slightly unclear over what you're being told I would make >>> sure that whoever is providing that information to you has read 9.2.1.3.1 >>> of the '16 edition of -13: >>> >>> 9.2.1.3.1 Sprinkler piping shall be substantially supported from the >>> building structure, *which must support the added load of the >>> water-filled pipe plus a minimum of 250 lb (115 kg) applied at the point of >>> hanging*, except where permitted by 9.2.1.1.2, 9.2.1.3.3, and 9.2.1.4.1 >>> >>> 9.2.1.1.2 deals with toggle hangers supporting pipe 1½" and smaller, >>> 9.2.1.3.3 covers flexible hose fittings, and 9.2.1.4.1 covers branch >>> hangers into a metal deck. >>> >>> It's pretty clear that the structure has to be able to support at least >>> the load noted in 9.2.1.3.1. >>> >>> As I am a principal member of the hanging and bracing committee, please >>> see the disclaimer below. >>> >>> sincerely, >>> >>> *Ken Wagoner, SET Parsley Consulting* >>> >>> >>> >>> * 350 West 9th Avenue, Suite 206 Escondido, California 92025 Phone >>> 760-745-6181 Visit the website <http://www.parsleyconsulting.com/> * >>> >>> *IMPORTANT NOTICE: This correspondence is not a Formal Interpretation >>> issued pursuant to NFPA Regulations. Any opinion expressed is the personal >>> opinion of the author and does not necessarily represent the official >>> position of the NFPA or its Technical Committees. In addition, this >>> correspondence is neither intended, nor should it be relied upon, to >>> provide professional consultation or services* >>> >>> *It should be noted that the above is my opinion as a member of the NFPA >>> Automatic Sprinkler System Hanging and Bracing Committee in accordance with >>> the NFPA Regulations Governing Committee Projects and should therefore not >>> be considered, nor relied upon, as the official position of the NFPA or its >>> Committees* >>> >>> >>> On 06/03/2020 8:25 AM, Jerry Van Kolken via Sprinklerforum wrote: >>> >>> I have a building where they are telling me the structural point loading >>> on the framing less than 250lbs. (140lbs) >>> >>> >>> >>> Advice? >>> >>> >>> >>> Jerry Van Kolken >>> >>> *Millennium Fire Protection Corp.* >>> >>> 2950 San Luis Rey Rd. >>> >>> Oceanside, CA 92058 >>> >>> (760) 722-2722 FX 722-2730 >>> >>> >>> >>> _______________________________________________ >>> Sprinklerforum mailing >>> [email protected]http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >>> >>> >>> _______________________________________________ >>> Sprinklerforum mailing list >>> [email protected] >>> >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >>> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >> > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org >
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