Ken, I will respectfully disagree with you on this point in that I believe the ‘straight line to avoid eccentric loading on fittings and fasteners’ of Section 9.3.5.11.5 is in fact a line running through the center of the braced pipe’s long axis and acting in a coaxial line along the long axis of the bracing member itself. The eccentric load Section 9.3.5.11.5 is referring to is the loading of the braced, not the braced pipe. This brace is not required to be located in a vertical plane passing though both of these axes. In many cases, this is not possible since the braced pipe may not be running parallel to and directly below a structural member to which it must be braced fo r spacing reasons. Listed/approved braced piping connections including: welded tab; Cooper B-line Figures 4A, 4LA, 4L; or others may be rotated as necessary around the axis of the braced pipe as long as the ‘longitudinal’ component of the horizontal seismic load required for this brace can be withstood for all brace components as indicated in calculations. A longitudinal brace need not be oriented in the vertical plane as discussed above, it needs to meet the minimum angle requirements of Figure 9.3.5.1.12.1 and those indicated in Section 9.3.5.11.8 and Tables 9.3.5.11.8 (a-c) in the plane where BOTH axes lie. Eccentric loading in this plane is not allowed. It should be noted that any brace on a pipe is going to induce an eccentric load on the BRACED pipe.
It is my opinion that Kyle’s proposal is correct if verified by calculation…and if the components, namely the Figure 4LA, are turned as necessary into the plane I discussed above. Ryan L. Hinson, PE*, SET** \ Burns & McDonnell Senior Fire Protection Engineer O 952-656-3662 \ M 320-250-5404 \ F 952-229-2923 [email protected] \ burnsmcd.com<http://www.burnsmcd.com/> 8201 Norman Center Drive, Suite 300 \ Bloomington, MN 55437 *Registered in: LA, MD, MN, PA, TX, & UT **NICET IV - Water-Based Systems Layout From: Sprinklerforum [mailto:[email protected]] On Behalf Of Parsley Consulting Sent: Tuesday, August 01, 2017 1:51 PM To: [email protected] Subject: Re: Longitudinal Bracing Question Kyle, The photos did show up, however they're very small. From what I could discern from the photos I'd have to conclude that the plan view and section view B would lead me to conclude that this installation does conflict with 9.3.5.11.5, as the brace fittings at the attachment to structure and attachment to the main would be subject o eccentric loading for which they may not have been listed/tested. When in doubt check with the good people at B-Line to see if their figure 825 was tested for such an installation, not to mention the figure 4A. I would doubt that it was. It is also possible that there are tension only brace fitting attachments to the structure which would allow what you're showing, however I simply have not designed bracing with that method enough to direct you to the correct equipment. I believe this is a circumstance where you're going to have to get the building structural engineer involved. I'm not sure how you're reaching the conclusion that a "standard configuration" would impart any sort of vertical force on the main. As for the adjacent lateral braces "work harder", in as polite language as I can generate - rubbish. Lateral bracing is only intended to resist horizontal motion perpendicular to the axis of the pipe. Consider - if the detail in the "top plan view" below was for a lateral brace it would still generate eccentric loads on the hardware, and that would be unacceptable. sincerely, Ken Wagoner, SET Parsley Consulting 350 West 9th Avenue, Suite 206 Escondido, California 92025 Phone 760-745-6181 Visit our website<http://www.parsleyconsulting.com/> On 08/01/2017 11:06 AM, Kyle.Montgomery wrote: Here is a picture of what I'm talking about (let me know if the picture shows up): [cid:[email protected]] It still maintains an appropriate angle from vertical. And it still resists motion "parallel to the axis of the system piping". But in doing so it will impart an additional horizontal load perpendicular to the axis of the pipe (lateral) whereas a standard configuration only imparts an additional vertical force. So it is making the adjacent lateral braces work harder, so to speak; Is that OK? -Kyle M -----Original Message----- From: Sprinklerforum [mailto:[email protected]] On Behalf Of [email protected]<mailto:[email protected]> Sent: Tuesday, August 01, 2017 9:18 AM To: [email protected]<mailto:[email protected]> Subject: Re: Longitudinal Bracing Question Thanks Ken. I was referring to this: * The only "angle" which really applies in providing longitudinal bracing is the measurement from vertical. That angle must be at least 30° and have a maximum of 90° from vertical (which is perfectly horizontal, and would make the brace parallel to the pipe. I am thinking in plan view, based on Kyle's original question, so any angle from vertical would 'appear' to be parallel to the pipe. To us Sprinkler Eccentrics, nothing is Minor :) Brad Quoting Parsley Consulting <[email protected]<mailto:[email protected]>>: > Brad, > > While the quote from NFPA 13 is entirely correct and the brace pipe > and fittings must be in a straight line, thus avoiding eccentric > loading on the fittings and fasteners, I did not say that the brace > has to be parallel to the pipe. > > What I did say was that a longitudinal brace resists horizontal motion > of the main in a direction which is parallel to that main. > > The angle, measured from vertical, must be at least 30° and can be as > much as 90° from vertical, which would make the brace pipe parallel to > the main, however that is not required. > > Minor but relevant clarification. > *Ken Wagoner, SET > *Parsley Consulting*** > *350 West 9th Avenue, Suite 206 > *Escondido, California 92025 > *****Phone 760-745-6181* > Visit our website <http://www.parsleyconsulting.com/> *** On > 08/01/2017 8:17 AM, [email protected]<mailto:[email protected]> > wrote: >> From 13-2016: >> >> 9.3.5.11.5 All parts and fittings of a brace shall lie in a straight >> line to avoid eccentric loadings on fittings and fasteners. >> >> The above means, to me anyway, that it is NOT ok to kick the >> longitudinal brace out at an angle as seen in plan view. In this way >> I think that is an angle that does matter, but Ken cleared it up by >> saying the brace pipe has to be parallel to the main pipe. >> >> As always, I am willing to stand to be corrected, >> >> Brad >> >> Quoting "Kyle.Montgomery" >> <[email protected]<mailto:[email protected]>>: >> >>> I knew where you were going, Steve, and I agree that this is a good >>> approach. We’ve gone this route in the past, but when you get to the >>> stage of the job where I’m usually involved (closer to >>> construction) and everyone has contracts for construction, it can >>> sometimes be contentious as far as who would provide and pay for >>> this additional engineering. So I was looking for ways to control >>> our own destiny, so to speak. >>> >>> Thanks for everyone’s input. >>> >>> -Kyle M >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of >>> Steve Leyton >>> Sent: Friday, July 28, 2017 3:25 PM >>> To: >>> [email protected]<mailto:[email protected]> >>> Subject: RE: Longitudinal Bracing Question >>> >>> What he said. To clarify my earlier comment – I did not intend to >>> suggest that you could use the trapeze values in NFPA 13 for hangers >>> and apply them to EQB anchorage. However, we have worked with our >>> structural engineers on previous projects to design for similar >>> conditions where the shear load bearing value of the strut (notice I >>> just said strut instead of trapeze) was specified by the SEOR and >>> was adequate for the applied loads of the specific braces we needed >>> to anchor. It CAN be done, but as Ken says, it can’t be done by >>> simply using the trapeze section moduli published in NFPA 13. >>> >>> Steve L. >>> Back Peddling, CA >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of >>> Parsley Consulting >>> Sent: Friday, July 28, 2017 12:53 PM >>> To: >>> [email protected]<mailto:[email protected]<mailto:[email protected]%3Cmailto:[email protected]> >>> iresprinkler.org> >>> Subject: Re: Longitudinal Bracing Question >>> >>> Forumites, >>> >>> Let's clarify a couple of items here. [All references to the 2016 >>> edition, and all emphasis is mine] >>> >>> * Longitudinal bracing on mains must be spaced no more than 80' >>> apart, per 9.3.5.6.1 >>> >>> * The distance from the end of the line and the last (or first) >>> longitudinal brace must no exceed 40', per 9.3.5.6. >>> * Your first longitudinal brace could be as much as 40' from >>> the end of the pipe run. >>> * The structural components of the building must be able to >>> resist the added seismic loads, per 9.3.5.1.2 >>> * This is something the building structural would have to >>> provide, as it's not something a sprinkler contractor should attempt >>> without some training and experience in structural engineering. >>> * A trapeze installed per NFPA 13 guidelines is not intended to >>> address loads other than gravity in the vertical orientation, and >>> any resistance to horizontal movement would have to be designed by a >>> structural engineer. >>> >>> * As long as the brace member (pipe, rod, flat, etc) does not >>> exceed the limits on the length imposed by tables >>> 9.3.5.11.8(a)-(c) having it be four feet to the nearest bar joist >>> should be no problem. >>> >>> * The only "angle" which really applies in providing >>> longitudinal bracing is the measurement from vertical. That angle >>> must be at least 30° and have a maximum of 90° from vertical (which >>> is perfectly horizontal, and would make the brace parallel to the >>> pipe. >>> >>> The addition of another flexible coupling on the main could create a >>> further requirement for additional lateral bracing within 24" of the >>> flexible coupling per 9.3.5.5.9. >>> >>> I hope that provides some guidance. >>> As I am a member of the hanging and bracing committee of NFPA 13, >>> 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 our 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 >> >> >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected]<mailto:[email protected]> >> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprink >> ler.org _______________________________________________ Sprinklerforum mailing list [email protected]<mailto:[email protected]> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected]<mailto:[email protected]> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
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