How to Guide

52
Plastics Technical Manual
Support Spacing For ABS, PVC
and CPVC Pipe
Adequate support for any piping system is a matter of great
importance. In practice, support spacings are a function of pipe
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fittings, and the mechanical properties of the pipe material.
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piping system, the location and type of hangers should be
carefully considered. The principles of design for metallic
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pressure piping systems, but with some notable areas where
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compress, distort, cut or abrade the piping.
All piping should be supported with an approved hanger at
intervals sufficiently close to maintain correct pipe alignment
and to prevent sagging or grade reversal. Pipe should also be
supported at all branch ends and at all changes of direction.
Support trap arms as close as possible to the trap. In keeping
with good plumbing practices, support and brace all closet
bends and fasten closet flanges.
(1) Concentrated loads (ie: Valves and other appurtenances)
should be supported directly so as to eliminate high stress
con centrations. Should this be impractical, then the pipe
must be supported immediately adjacent to the load.
(2) In systems where large fluctuations in temperature occur,
allowances must be made for expansion and contraction
of the piping system. Since changes in direction in the
system are usually sufficient to allow for expansion and
contraction, hangers must be placed so as not to restrict
this movement.
(3) Since plastic pipe expands or contracts approximately
five times more than steel, hangers should not restrict this
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should not force the pipe and fittings into position.
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possible. To prevent damage to the pipe, file smooth any
sharp edges or burrs on the hangers or supports.
(5) Plastic piping systems must not be placed alongside
steam or other high temperature pipe lines or other high
temperature objects.
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determined by the maximum operating temperature the
system will encounter. The piping should be supported
on uniform centers with supports that do not restrict the
axial movement.
(7) For vertical lines, it is recommended that an engineer
design the vertical supports according to the vertical load
involved.
(8) Changes in direction should be supported as close as
practical to the fitting to avoid introducing excessive
torsional stresses into the system. Please see the associated
chart showing the recommended support spacing
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These spacings apply to continuous spans of uninsulated
lines, with no concentrated loads, conveying liquids with
specific gravities of up to 1.00.
NOTICE: The above information provides general guidelines.
It should be used only as a reference and not as a guarantee of
performance. Specific installation instructions and techniques
may be required as a result of local plumbing and building
codes, engineering specifications and instructions.
DESIGN & ENGINEERING DATA
Failure to compensate for expansion and contraction
caused by temperature change may result in system
failure and property damage.
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