That's a good question. Why are the hangers only 6ft apart? Just because you're supposed to hang at the panel points doesn't translate into having to hang from each joist. Hang at the panel points but space the hangers in accordance with NFPA 13. Hanging at every joist makes no sense. When in doubt contact the joist mfgr and talk to one of their engineers, NOT the A/E's structural engineer, The MFGR's Engineer. They can tell you what loading was designed into the truss/joists and where the appropriate points for attachment are located.
Don't confuse the size of angle iron for trapeze hangers per NFPA 13 with the size of the angle on the bottom chord of engineered joists. It isn't the same thing and not relevant. You're comparing apples to oranges. The hanger is required to support the 250 lbs plus the water filled pipe, but what it is attached to must also. So if you have light steel construction you might have to span across more than one joist in order to distribute the weight of the pipe. Again, a lot of different variables. Ask questions and ask the right people and ask more than one person when answers aren't consistent. Then make sure to document EVERYTHING. Craig L. Prahl, CET Fire Protection Group Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [EMAIL PROTECTED] http://www.lg.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Canham Sent: Thursday, June 14, 2007 2:52 PM To: [email protected] Subject: RE: Hanging branch lines from panel points Isn't the hanger required to hold 250 pounds plus the weight of the pipe full of water? Not just the 23 pounds? Dave Canham -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matthew Stone Sent: Wednesday, June 13, 2007 1:08 PM To: [email protected] Subject: Hanging branch lines from panel points We are installing a grid system in a super store and the general contractor is demanding that we hang all piping within 6" of a panel point of the web-type roof joist. There is a detail showing sprinkler pipe to be installed in this location and a structural drawing showing the location of the main. We naturally installed the main to meet these criteria. The branch lines are run perpendicular to the joists so hangers for the branch lines are spaced at 6'-0" apart which is at every joist. This means that there is a 23 lb load at each hanger. Table 9.1.1.6.1(b) requires a 2 × 2 × 1/8 angle iron and the joists have a 2 x 2 x 3/16 angle iron on top. Has anyone else come across this requirement in the contract drawings and had it applied to all sprinkler pipe? We can use trapeze hangers to meet this demand by the GC but it will also raise the question in those of you who look up when you are in super stores, "Was this system installed by a licensed contractor?" Matthew Stone _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
