Majority of pipe supports in a plant facility will fall under the category of rigid supports. A rigid support is primarily used to support the weight of pipe and its components. Hence its purpose is to prevent the downward movement of pipe. Support intervals or spans are chosen such that the pipe does not sag excessively due its self-weight and the weight of its contents and insulation. A bare pipe may be allowed to rest on a structural member or if the pipe is insulated it may be provided with a shoe. In the later case the bottom of the shoe will rest on the structural member. A shoe support provides a larger contact surface with structural steel member as against bare pipe resting on structural member which results in line contact. Figure below shows examples of shoe support configurations which are most commonly used.
The choice of shoe type depends on the size of pipe and the weight of the pipe and its contents. For smaller pipe sizes and lesser loads, a single T-section cut from structural steel section such as IPE or HEA member is welded to the bottom of pipe to form a shoe support. As the pipe size increases and the pipe becomes heavier the shoe support is designed with two vertical members which allows the pipe load to be spread over a larger surface area of the pipe wall resulting in lower local stresses in the pipe wall. The shoe support with saddle uses a reinforcement saddle plate that is welded to the bottom of the pipe. The saddle plate usually subtends an arc of 90° or 120°. The saddle plate can be fabricated from the parent pipe material. However if the parent pipe has high wall thickness, the saddle plate is formed from plate material such as ASTM A36 for carbon steel pipes. A pipe saddle spreads the pipe load over a much larger portion of the pipe surface area and substantially reduces the local pipe wall stresses.
Pipe shoes also serve as convenient means to provide slope on lines routed on pipe racks by using shoes of different heights to achieve the required slope. This allows the pipe rack to be kept at a constant elevation for the other lines which are not required to be sloped.
Pipe Trunnion or Dummy Supports
Another example of rigid pipe support is a dummy support also called trunnion support.
A dummy support consists of a tubular member which is welded to the pipe instead of structural member.
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The Anchorage Group has created an A-Z Guide of Terminology used in the pipeline and pipe support system