Is there any experience with review comments or specifications calling for a flexible coupling on a welded steel discharge pipe supplying water to a fire pump?
2010 IBC; 2010 NFPA: U.S. Government job: Category 4 Occupancy (essential) Two independent water supplies (municipal underground and above ground tank) Frequency of seismic events in this area: very low, and not strong 10% and 30% of gravity for the 1 and 0.2 second period spectral response acceleration. NFPA 22 is the hammer used to justify asking for the flexible coupling. The only mention of flexible coupling in NFPA 22 is at Figure Annex B.1.x, for underground fiberglass tanks. I have not seen a flex coupling for a water tank to separate steel piping-that-is-fixed-to-the-ground and steel-pipe-that-is-fixed-to-the-tank, whether the tank be for water, liquid petroleum or LNG tanks. Maybe the Japanese do it, but I have not seen it in California quake country, either. *Questions:* 1. Is there a nationally accepted practice whereby flex-joints are required between tanks and their ground based piping? 2. Are flexible connections listed for outdoor service where freezing and strong solar radiation are present? 3. Would not seismic bracing be sufficient (a method most of the O&G industry engages) rather than a flex joint ? Bracing against seismic event is the approach taken by O&G, and seems to be the intent of NFPA 22 (Sections 13.5.2.2. and for anchor bolts 5.3.2) 2. Since we are outside, not indoors, do the requirements of NFPA 13 bracing apply (there is no direct reference from NPFA 22 to NFPA 13 with regards to earthquake bracing) apply, since there is no "structure" with which to make a comparison of equivalence [3],[4]? [1]. IBC-2006-Figure1613_5(01) one second period spectral response [2]. 2013/2010 NFPA 24 12.2.5 To minimize or prevent pipe breakage where subject to earthquakes, aboveground pipe shall be protected in accordance with the seismic requirements of NFPA 13. [3]. 2010/2013 NFPA 13 Section 9.3.1.2 Alternative methods of providing earthquake protection of sprinkler systems based on a seismic analysis certified by a registered professional engineer such that system performance will be at least equal to that of the *building structure* under expected seismic forces shall be permitted. [4]. 2013/2010 NFPA 13 Section 9.3.3.1 An approved seismic separation assembly shall be installed where sprinkler piping, regardless of size, *crosses building seismic separation joints *at ground level and above. Additional references 2013 NFPA 22 4.12.4.1 Tank structures shall comply with the local building code for seismic requirements. 4.12.4.2 Specific design criteria shall be contained in the appropriate chapter for the particular tank, or in local codes, whichever is more stringent. 5.3.1 Tanks shall meet the requirements for resistance to earthquake damage in accordance with the earthquake design provisions of AWWA D100. Personally, I think corrosion, and not earthquake would have been a better focus of taxpayer money . Maybe the specification writers thought to include an internal tank liner AND a passive cathodic protection system, to extend the tank life to at least a hundredth of the 1000-year earthquake we are designing for . Scot Deal Excelsior Fire/Risk Engineering _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
