It would seem to me that your fire marshal has a point. NFPA-13, 2002,
9.3.5.8.1 indicates that for horizontal loads sway bracing shall be
tight. If the wire is slack, it isn't per NFPA-13. Also, A.9.3.5.2.2
discusses some of the considerations for tension only sway brace
methods, including prestretching to eliminate permanent construction
stretch. Perhaps the braces in question were not pre-stretched?
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]> e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com> website
Bill Minkel wrote:
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
_______________________________________________
Sprinklerforum mailing list
[email protected]
http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum
