American Fire Sprinkler Association
9696 Skillman, #300 Dallas, Texas 75243
Ph: (214) 349-5965 Fax: (214) 343-8898
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TECHNICAL UPDATE
DECEMBER 8, 2006
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"Are the seismic provisions in NFPA 13: 9.3.5 intended to be applied
in 13R applications utilizing CPVC piping, particularly where no rods
are used for hangers. Approved strap type Hangers and fasteners are
used for CPVC piping?"
We have reviewed the 2002 edition of NFPA 13R as the applicable
standard. Our informal interpretation is that it is necessary to
apply the sway brace requirements.
Piping support is required by section 6.6.6 of NFPA 13R and shall
comply with NFPA 13. There are no exemptions for sway bracing in the
lateral and longitudinal directions provided for CPVC piping in the
model codes. The manufacturer's data sheets also indicate the
systems to be braced according to NFPA 13. Therefore, sway braces
should be applied to the sprinkler system. It is reasonable to
equate the strap type fasteners to hanger rods less than 6 inches as
being able to adequately control horizontal movement perpendicular to
the main. This allowance to act as a lateral sway brace is
identified by 13:9.3.5.3.7. There is no similar allowance for short
rods to act as a longitudinal brace because it cannot resist the
horizontal force parallel to the main. The issue here is that the
brace must be tightly fastened to the pipe in order to resist
movement. Obviously a swivel ring with a short rod would not do
this. Although the strap might be tight enough, there is a structural
limit of the CPVC to resist compression when trying to ensure the
brace is adequately tight. This is reflected by the fact that there
are no listed longitudinal sway braces. There are only listed
lateral sway braces which must be attached as an offset lateral brace
acting as a longitudinal brace as discussed under 13:9.3.5.3.5. As
such, you must use listed sway braces for this function.
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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) 2006, American Fire Sprinkler Association. All Rights
Reserved
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