UFC 4-390-01
23 July 2003
possible. Piping alone should not be used as the sole support for
relatively heavy components (e.g., large valves, moisture
separators or filter housings). Components should be supported
so that the force required to operate them (or other normal
operational loads) does not cause visible deflection, rotation or
vibration. One line should not be used to support another,
although clamp blocks may be used to support two or more adjacent
lines as long as the blocks are attached to non-piping structural
members.
B.8.1.3 Piping Flexibility. Piping should be designed to have
sufficient flexibility to prevent failures resulting from the
conditions listed in Section B.8.1.1.
In certain cases piping flexibility calculations are required by
the SCA as a further measure of assurance prior to system
fabrication. Detailed sketches of piping under examination may
be required with the calculation report.
Where required,
calculations should show maximum stresses and their location in
each section of piping under examination. Calculations should be
submitted in a detailed form that will permit their review
without difficulty and should include a statement delineating the
following:
a)
Theoretical basis of the calculations
b)
Method of performing the calculations
c)
Simplifying assumptions
d)
Sign and symbol conventions
e)
Assumed material and dimensional data
f)
Other pertinent information such as hull deflections
The piping flexibility analysis should also consider the
flexibility of piping components. The applicant's piping
flexibility analysis should include calculations of the bending
moments, twisting moments, and reaction forces imposed on each
critical component in the piping system. Flexibility analysis is
not required for pipe up to and including 3/8 inch IPS or for
tubing up to and including 1/2 inch OD. Additional information
on the flexibility analysis can be found in ASME B-31.1.
Table B.1
Pipe Support Spacing
PIPE SUPPORT SPACING
Nominal Pipe Size
Span (Inches)
(Inches)
Gas Service
Liquid Service
1/8
24-28
18-24
78
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