I agree that you would have to follow NFPA 13/15 hanger requirements for spacing of pipe stands you are building to support pipe around like a pump set or a transformer. In the pipe rack however I think you can only use what you are given. In the past we have used flanges to join bulk pipes in the rack. Threaded branchlines hold up okay with hangers every 20 ft. Of course we did all of this back before the scientists got involved in NFPA 13 so if it was solid, wouldn't wiggle if pulled on, didn't fall down from its' own weight and didn't move when flow tested it was good enough.
Ron Fletcher Aero -Phoenix -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of craig.pr...@ch2m.com Sent: Thursday, November 08, 2012 7:29 AM To: sprinklerforum@firesprinkler.org Subject: RE: Pipe support spacing requirements for structural supports Whether it's a pipe stand, a hanger or pipe rack, they must conform to the spacing requirements of the applicable standard. NFPA 15(2012) 5.6 defers to NFPA 13 for hangers. I can't find any A10.4.1 in NFPA 15, 2012. So no, 20' hanger spacing is not compliant with the NFPA 13 or NFPA 15 standards. The assertions of the structural engineer are incorrect. Additionally, I would suggest looking at the installation manuals provided by the coupling manufacturers to see if they refer to any particular support spacing requirements if there is specific direction needed. Craig L. Prahl, CET Fire Protection CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 craig.pr...@ch2m.com -----Original Message----- From: sprinklerforum-boun...@firesprinkler.org [mailto:sprinklerforum-boun...@firesprinkler.org] On Behalf Of Hinson, Ryan Sent: Tuesday, November 06, 2012 7:07 PM To: sprinklerforum@firesprinkler.org Subject: Pipe support spacing requirements for structural supports I've got a couple projects which have pipe racks for supporting above grade firewater piping. These rack supports are spaced at 20' or more on center. From the NFPA 13 Handbook at the beginning of Chapter 9, pipestands are to have the same safety factors as hangers. NFPA 15 is suggested for additional guidance. NFPA 13 limits hanger spacing to 15'. NFPA 15 (2012) Sections 6.3.2.2 and 6.3.2.3 state that firewater piping shall be supported under fire conditions and shall be supported from steel or concrete structural members or pipestands. "Do these also need to conform to the 15 ft maximum spacing?" I've received this question from a structural engineer regarding the pipe support requirements for NFPA 13 (2010) Chapter 9. His assertion is that this refers to pipe stand and pipe hanger spacing requirements for piping 8" and smaller only. As such, his feeling is that there are no limits on spacing for concrete and steel support conditions other than those required per AWWA M11 4th Edition Chapter 7 and sound structural engineering design. Incidentally, NFPA 15 (2012) Section 6.3.2.2 calls out structural supports specifically as if there is some difference for their design and does not actually provide a limit. Both NFPA 20 (2010) Section 4.13.5 and NFPA 24 (2010) Section 12.1 state above ground piping and fittings must comply with NFPA 13 regarding hangers and supports. NFPA 15 Section A.10.4.1 refers to AWWA M11 as applicable for installation of pipe and fittings. NFPA 15 Table 6.3.2.2.2 only goes up to 8" pipe. AWWA M11 has some pipe support requirements for steel piping. At first glance, they do not appear applicable for fire water systems as they are not specifically included in Chapter 1 Uses. Chapter 7, Supports for Pipe, states the load is determined to be the weight of the water filled pipe. NFPA 13 requires the load to be 5 times the weight of the water filled pipe (see Section 9.1.1.2(1)). The 5 times load factor seems to be only applied to hangers and stands as well, applying this to steel and concrete supports would be too conservative. It appears the design of the steel and concrete supports would be covered by AISC 13th edition, ASCE 7-05, and ACI 318 codes. As an example to the above difference: See 8" Schedule 40 pipe (this is standard weight pipe). The wall thickness is .322 inches. Per AWWA M11 Table 7.1, this approximately nominal 5/16" wall thickness can have supports 45 ft apart. 8" schedule 10 (3/16" wall thickness) can be spanned up to 38' according to this table! I'm not up on the nuances of piping and deflection but I believe the intent is to provide considerable safety into the supports of all types for firewater related piping. Is it the opinion of the forum that 15' along with the allowable extensions per NFPA 15 is the maximum or are we to use structurally designed supports at their stated allowable spans for supporting this piping? What say you? Ryan L. Hinson, EIT, SET Senior Fire Protection Engineer, Aviation & Facilities Group Burns & McDonnell Minneapolis-St. Paul Office 8201 Norman Center Drive, Suite 300 Bloomington, MN 55437 Direct: 952-656-3662 Fax: 952-229-2923 rhin...@burnsmcd.com www.burnsmcd.com<BLOCKED::www.burnsmcd.com> Proud recipient of PSMJ's Premier Award for Client Satisfaction -------------- next part -------------- An HTML attachment was scrubbed... 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