Chemical Engineering October 2020 - 29

The practical approach is to evaluate
the expected displacement that
necessitated the slide or guide, and
check to see if the post and its bottom
attachment (weld or base-plate
anchors) can tolerate that deflection
and bending moment. If it can,
then the slide or guide is likely not
needed, and a simple U-bolt might
suffice (Figure 7).
or guide should not be needed, because
the support will bend before
the slide or guide begins to move.
Again, buckling stability of the support
needs to be taken into consideration,
especially if the post is not a
closed section member.
In the case of an anchor on a tall
post, the anchor needs to be evaluated
for the stiffness of the post to
make sure the resulting deflection
doesn't create issues in the rest of
the piping system. And again, a Ubolt
may be able to transfer all the
load the post can handle. Buckling
stability of the support needs to be
taken into consideration in all cases,
but especially if the post is not a
closed section member.
Tall post with a cantilever, and either
a pipe slide, guide, or anchor.
This case is very similar to the one
just described, and is commonly
seen in retrofitted or expanded plant
areas. The principles are the same,
but with torsion of the post added
(Figure 8).
The support is likely flexible
enough that slides or guides are not
necessary, and this can easily be
proven by comparing the expected
displacement of the pipe to the deflection
resulting from the calculated
friction force from the slide/guide. If
Long threaded rod hanger and
adjustable pipe roller. This is another
case that is commonly seen,
and like the case of the tall post, the
stiffness of the threaded rod hanger
is likely not enough to provide the resistance
needed to cause the roller
to roll, so the roller will just act as an
expensive clevis hanger (Figure 9).
Pipe support design and engineering,
like all other areas of engineering
in an industrial plant, can be
challenging. With a little understanding
of the various situations, and by
not always resorting to an off-theshelf
solution, the design can often
be made simpler, more reliable, less
expensive and easier to install. ■
Edited by Scott Jenkins
Author
FIGURE 9. The stiffness of a rod hanger, like the
one shown here, likely will not provide the resistance
for the roller to roll
the friction force is enough to deflect
the support to a degree that is equal
to or greater than the anticipated
pipe displacement, then the slide
Scott Feller is the executive vice
president of operations at AMG,
Inc. (1497 Shoup Mill Rd, Dayton,
OH, 45414; Phone: 937-2604630;
Email: sfeller@amg-eng.
com). AMG, Inc. is a full-service
engineering consulting firm that
provides a broad range of design
and construction support services
to various chemical processing
and related heavy industrial segments.
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Chemical Engineering October 2020

Table of Contents for the Digital Edition of Chemical Engineering October 2020
