The simple answer is "a thing that transfers the weight of a pipe to a supporting structure," but in order for a pipe support to do its job well, engineers have to consider a lot of factors before picking the right support for the task.
What is a pipe support? Simple answer: a thing that transfers the weight of a pipe to a supporting structure.
I say “a thing” because it really can be anything. The only limit is one’s imagination, though a word of warning: just because something can support a pipe doesn’t mean that it necessarily should.
How do engineers choose the right support, then? There are a lot of options, of course, and ignoring important factors can result in damage to the pipe, damage to the supporting structure and costly repairs. See our blog post about the costs of corrosion.
There are two main factors that need to be considered when selecting a pipe support: 1) what kind of load will need to be supported; and, 2) what are the conditions under which the support will be expected to function?
There are two kinds of loads that are present in piping systems: primary and secondary. A primary load is relatively constant, predictable and sustained. Examples include gravity and internal pressure caused by fluid in the pipe. There are a few types of primary loads that aren’t constant, too. These include but aren’t limited to wind, earthquakes and sudden water or steam pressure. These are just a few of the conditional concerns that will need to considered.
A secondary load is one caused by movement, expansion and contraction, vibration, etc. For example, pipes that carry fluids of extreme temperature can expand or contract over time. A pipe support on this type of pipe would need to account for this type of secondary load.
Once the load and operating conditions have been determined, an engineer can turn his or her focus towards selecting the right kind of pipe support.
How are Pipe Supports Classified?
The first way pipe supports are classified is by how they connect to the pipe. A primary support connects directly to the pipe. A secondary (or structural) support is connected to the foundation or structure and supports the primary support.
The second way pipe supports are classified is by their construction. Generally speaking, there are three types: rigid pipe supports, elastic or spring pipe supports and shock absorbing pipe supports (or snubbers).
Rigid Pipe Supports – As the name suggests, rigid pipe supports that have little-to-no flexibility. In terms of function, rigid pipe supports are designed to limit movement in certain directions and can act as an anchor, a rest, a guide or as a rest-guide (see further down for more info on pipe support functions). Examples of rigid supports include: pipe shoes, wear pads, slide plates, FRP flat plate, t-slides, pipe hangers, dummy legs and struts. Rigid supports can be adjustable, as well, in order to accommodate the change in piping angles at critical locations.
Elastic or Spring Pipe Supports – A spring pipe support utilizes a compression spring as means to support a secondary load such as thermal expansion. There are two main types of spring supports: a variable effort support and a constant effort support. In the case of variable effort spring pipe supports, the load changes (< 25%) as the pipe moves, generally less than 50mm in a vertical direction relative to the support. A constant effort support is used when larger vertical movements (up to 250mm) occur that cause the load to change more than 25%. The most common example of a constant effort spring support is the bell crank.
Shock Absorbing Pipe Supports / Snubbers – In the event of a significant and dynamic change in energy, a shock absorbing pipe support (or snubber) instantaneously forms a restraint between the pipe and the structure. When pipe displacement is caused by an event such as an earthquake, the pipe and the structure are protected when the force acting on the two components is absorbed and harmlessly transferred. An example of a snubber is an insulated pipe support, which reduces energy dissipation.
The third way pipe supports are classified is by their functions.
Loose Support – This type of pipe support is meant to support only the pipe weight in the vertical direction.
Longitudinal Guide – This type of pipe support is commonly used in conjunction with a loose pipe support and is designed to limit movement in the transverse direction.
Transverse Guide – Like the longitudinal guide, a transverse guide is commonly used with a loose pipe support. However, a transverse guide is designed to limit movement in the longitudinal direction. It is also know as an “axial stop.”
Fixed Point or Anchor – A fixed point or anchor support restricts movement in all three directions. A fixed point support is not welded, but allows for rotational movement. An anchor support is welded and is used when all movement, both liner and rotational, needs to be restricted.
Limit Stop Support – This pipe support allows for free movement up to a certain point.
In addition to the above, custom supports can be manufactured that combine any of the functions for special use cases.
As you can tell, pipe supports exist in many shapes and sizes and a pipe support’s ability to successfully perform its job relies on an engineer’s understanding of the load being supported and the conditions in which the support will function.