American Fire Sprinkler Association
12750 Merit Dr., Suite 350 Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908
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TECHNICAL UPDATE
March 27, 2008
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"Where CPVC piping is used in a NFPA 13 building in accordance to
6.3.6.1 and it's listing, to what extent do the seismic requirements
of Section 9.3.6 apply when the piping is hung by a rod and ring? To
what extent does Section 9.3.5 apply on CPVC mains that are typically
11/4-in. to 2 in. in size?"
We have reviewed the 2007 Edition of NFPA 13 as the applicable
Standard. Our informal interpretation is that both sections are
applied regardless of the pipe type.
Question #1. Section 9.3.6 addresses the requirements for branch line
restraint and there is no differentiation in this section regarding
the type of pipe (steel vs. CPVC). Thus branch line restraint should
be provided for CPVC piping. If the branch lines are provided with a
rod and ring, Section 9.3.5.6 indicates that when the rods are less
than 6 in. long measured between the top of the pipe and the point of
attachment to the building structure, additional restraint is not
required provided the rod and ring is installed according to the
manufacturer's requirements. If the rod is greater than 6 in., then
additional restraint should be provided and spaced in accordance with
Section 9.3.6.4.
Question #2. Sway bracing of the piping in Section 9.3.5 applies to
all feed and cross mains regardless of size. Lateral sway bracing also
applies to branch lines and other piping with a diameter of 21/2-in.
and larger. There is some confusion since the tables in Section
9.3.5.3.2 refer to schedule 10 and 40 steel pipe. This led to some AHJ
interpretations that only schedule 10 and 40 steel pipe can be used
for sprinkler systems. This was not the intent of the committee and
the committee discussed the use of CPVC pipe during the ROP meeting
and a table for CVPC will be provided in the 2010 edition. An
alternate source to calculate the sway brace spacing requirements is
ASCE 7-05. In closing, Sections 9.3.5 and 9.3.6 have to be applied as
applicable for CVPC piping.
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Technical Update is prepared by the Technical Services Dept. of the
AFSA: Vice President of Engineering and Technical Services Roland
Huggins, a PE registered in fire protection engineering; Phill Brown,
a NICET IV certified automatic sprinkler technician and NFPA Certified
Fire Protection Specialist (CFPS) and Tom Wellen, a degreed fire
protection engineering technologist. This is provided with the
understanding that the AFSA assumes no liability for this opinion or
actions taken on it and they are not to be considered the official
position of the NFPA or its technical committees.
Copyright (c) 2008, American Fire Sprinkler Association. All Rights
Reserved
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