The wire seismic braces essentially bear no dead load, the piping supports bear all the load. The wires are prestressed and pulled taut then crimped when installed. There is no provision for post-installation tensioning. The wires are calculated to resist the lateral loads imposed by an earthquake during which time they are in tension. The local Fire Marshall has apparently never seen this application before and is skeptical, implying that if we had done it right the first time there would be no problem.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - work Sent: Friday, February 02, 2007 6:25 PM To: [email protected] Subject: Re: Seismic bracing - wire rope Think about this for a moment. What would keep tension on the wire? One thing, the weight of the pipe. This means that the wire has to be allowed to carry a certain amount of the weight of the pipe. I would check the breaking strength of the wire, but I would assume that it could probably hold more than you think. The solution may be as simple as loosening up the knerl nut a turn or two (unless it's 40 ft in the air; then nothing is simple) As to what would cause it to loosen up over time, what about thermal changes from when it was installed to now. Was it installed and set cold and is now in a heated building? If so, the wire might have expanded differently than the rest of the system, causing slack. Also, have the upper or lower supports secure? Is there evidence of damage? At 12:47 PM 2/2/2007, you wrote: >Generally The "Wire Rope systems are "Tension Only" systems. These are >intended to be under tension in all directions at all times to prevent >movement of the pipe. If you have "Slack" you aren't preventing >movement. Call the MfG of the product your using and get their take on >it. It's their engineering that the product installation is based upon, >have them review the installation and placement for this application. > >Thom McMahon >Firetech, Inc. >2560 Copper Ridge Dr >Steamboat Springs, CO 80488-2136 >Tel: 970-879-7952 >Fax: 970-879-7926 >----- Original Message ----- From: "Richard Battershell" ><[EMAIL PROTECTED]> >To: <[email protected]> >Sent: Friday, February 02, 2007 10:06 AM >Subject: Seismic bracing - wire rope > > >> >>How much , if any, slack is allowed in wire rope used for seismic bracing? >>Our fitters install the product we are using according to the >>manufactures directions and recommendations, but after a period of >>time (days/weeks) you can see slack in some of the braces particularly >>the lateral bracing. I believe this is caused by the pipe getting >>knocked around by other trades during the installation of their work. >>In any case the fire marshal has questions that I need to be prepared to answer. Please help. >> >>Thanks in advance. >> >> >>Richard Battershell >> >> >> >>_______________________________________________ >>Sprinklerforum mailing list >>[email protected] >>http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >> > > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut 860-535-2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
