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[
EJ GUIDE ]
Hinged/Gimbal Expansion Joint Examples
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When thermal expansion or other movements want to bend a pipe, in
order to lower stresses, a controlled bending point can be
added with a hinge or gimbal expansion joint. The hinged unit
will limit bending to only one plane, and the gimbal will
permit bending in all planes. The piping is always in tension
because the pressure thrust is contained within the system,
and main pressure thrust anchors are not required. Generally,
only guides and intermediate anchors are needed, as shown in
the examples. The full weight of the pipe between these
expansion joints can be carried by them. With proper hinge and
gimbal structure, the weight of additional pipes can also be
supported as well as wind loading. |
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Example 1
Two hinged expansion joints in a straight pipe run will
permit lateral deflection of the pipe, just as a universal
expansion joint will. However, the axial thermal growth will
not be absorbed within the expansion joints. This example
uses a flexible straight pipe section between two elbows to
accept the large thermal expansion of long pipe runs on
either side. Planar guides, or guides which permit movement
in a plane perpendicular to the pipe as well as axially,
should be added because some pipe bending may occur.
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Example 2
In this example a highly flexible pipe loop is created with
a double set of the arrangement shown in
Example 1. The top of the loop is anchored with an
intermediate anchor, and each side operates independently of
the other.
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Example 3
A highly efficient replacement for a rigid pipe loop is
depicted here with three hinged expansion joints. Using four
90 degree elbows, this "loop" has only two "legs" with short
pipe lengths. These features develop much lower flow losses
than a common pipe loop for the same axial travel. Pipe
guides should be used near the outer expansion joints. Only
intermediate anchors are needed.
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Example 4
The three pin arch system shown in this example accepts
deflections in all directions and operates in the same
manner as the loop shown in Example 3.
Because the movement of each bellows is highly controlled,
and limited to bending only, it is one of the most reliable
arrangements for large pipe and vessel deflections. When
hinged expansion joints are used, the movements are confined
to a single plane. When at least two gimbal joints are used,
the movements accepted can be in all directions and in any
plane.
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EJ Guide |
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= Featured Product =
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U.S. Bellows, Inc. Designed and Fabricated 50
Universal Expansion Joints for an Air Force Base in New Mexico
(Ref#91376-A1, EA) 11/14/2007
U.S. Bellows, Inc. fabricated 50 expansion joints from 304L
stainless steel. The expansion joints were 6" and 8" sizes. The 6"
expansion joints are 24" face to face and the 8" expansion joints
are 26" face to face. All of the expansion joints are fabricated
with liners that are also made with 304L stainless steel. The design
temperature was 200°F and the design pressure was 200 PSIG. The
expansion joints were dye-penetrant tested and hydro tested at 300
PSIG. U.S. Bellows, Inc. provides 100% customer satisfaction in
terms of quality and delivery.
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FAX: (713) 731-8640