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Discussion
and References
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Information about
Spacing Between Support
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Design of Piping
Systems, The M. W. Kellogg Company
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Books & Tables
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Design of Piping
Systems, The M. W. Kellogg Company
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Pipe
Properties
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Insulation
Weight Factor
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Insulation
Density
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ASME Sec.
II D Table TM-1 ( Modulus of Elasticity,
E )
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Spacing vs. Stress
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(The spacing is based
on a fixed beam support with a bending stress not exceeding 2,300 psi as per
table 121.5 of ASME B31.1).
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In most cases an
estimate of the stress can be obtained from the equation for beams:
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(U.S. Customary
Units)
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& =
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1.2WL²
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L =
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(
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SZ
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½
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(From Fig. C-16, Design of Piping Systems, The M.
W. Kellogg Company,
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Z
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1.2W
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Published by Stellar Editions, 2016).
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(SI Units)
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& =
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981WL²
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L =
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(
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SZ
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½
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Z
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981W
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Where:
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S
= maximum bending stress, psi (Mpa)
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W
= total unit weight, lb/ft (Kg/m)
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L
= pipe segment, ft (m)
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Z
= section modulus, in³
(mm³)
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For larger concentrated loads, such as those
produced by valves, vertical sections, branches, etc., Supports must be
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placed as close as possible.
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The effect of concentrated loads (valves, etc.)
not located in the supports must be approximated by multiplying the
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stress by 2P/WL, where “P" is the
concentrated load in pounds.
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Spacing vs. Deflection
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(Pipe deflection could
be limited to 0.1 in. as per table 121.5 of ASME B31.1)
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The deflection of a
section can be approximated by the following formula:
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(U.S. Customary
Units)
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& =
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17.1WL⁴
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L =
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(
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&EI
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¼
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(From Fig. C-17, Design of Piping Systems, The M.
W. Kellogg Company,
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EI
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17.1W
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Published by Stellar Editions, 2016).
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(SI Units)
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& =
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98x10⁶WL⁴
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L =
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(
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&EI
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)
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¼
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EI
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98x10⁶W
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Where:
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&
= Deflection, in. (mm)
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W
= total unit weight, lb/ft (Kg/m)
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L
= pipe segment, ft (m)
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E
= modulus of elasticity, psi (N/mm²)
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I
= moment of inertia, in⁴ (mm⁴)
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