Clamp and Support for Pipe

To stabilize the location of utility pipes, specific connections and tools are needed, and it is better to gather specialized information for ordering them. These connections are known by various terms. For example, in industries, they are referred to as pipe supports.

Choosing the correct and logical clamps and pipe supports is vital for the success of a project. For the proper execution of installation operations, it is necessary to have supports in certain sections of the pipes at the installation site. The selection of appropriate clamps or supports is considered at all stages of design and construction during the execution phase.

Important Points in Designing or Selecting Supports

The design of supports, like other parts of piping, requires study and experience and should be considered from the beginning of the project in the preliminary phase, with the necessary technical specifications provided according to the needs of each project to the piping designer. In any case, the following points should be considered in the design of supports:

Study the technical specifications provided for supports at the beginning of the project (if available) to select the appropriate support during the design.

Consider the design temperature of the pipe to determine the strength and type of material for the support and necessary measures for insulation, etc.

Have sufficient information about the materials of the piping system and support accessories to reduce galvanic reactions at the connection points of the support to the pipe.

Maximize the use of existing structures, especially main structures, to reduce the number of supports and eliminate complex supports.

Standardizing types of supports (Standard Support Drawing) to reduce the number of required support drawings.

Review the feasibility of the designed supports and simplify the design, for example, making it easy to support pipes and avoid connecting supports to piping accessories such as fittings.

Bring supports as close as possible to components that act like concentrated forces in the system, such as valves and flanges, vertical pipes, connection points of two pipes, and changes in the direction of pipes in the horizontal position.

The possibility of repairing the piping system.

Consider the displacements of pipes and equipment and avoid rigidifying the piping system.

Consider external forces such as wind, earthquakes, and internal forces such as the discharge of safety valves.

Pay attention to the interference of foundations and terraces.

Different Types of Supports

Supports can generally be divided into four main categories:

Weight supports (Weight Support) such as ..., Sleeper, Saddle, Rod Hanger, Shoe

Rigid restraints (Rigid Restraint) such as Guide, Stop, U-Bolt, etc.

Dynamic supports (Snubber) such as Shock Absorber, Spring, ...

Sway Brace for controlling vibrations.

To complete the above information, attention to the following point is essential. As we know, each element in three-dimensional space has six degrees of freedom: three translational degrees along the X, Y, Z axes and three rotational degrees around the X, Y, Z axes. It is essential to note that the goal of supporting is not to completely restrict translational and internal movements but to control the mentioned movements in the desired direction, and this is done considering the geometric conditions of the line, temperature, length, diameter, etc., to provide appropriate flexibility for the piping system.

Next, we will further examine the mentioned classifications.

Weight Supports

Weight: The vertical force is controlled in two ways: from the bottom of the pipe and from the top of the pipe. If the vertical force is controlled from the bottom of the pipe, it is called a Rest, and if that force is controlled from the top of the pipe, it is called a Hanger.

Some of the supports used as Rest include Shoe, Saddle, Dummy, Trunnion.

Shoe: Usually made of a channel or sometimes a plate in various sizes.

Saddle: Used to spread the force applied to the pipe when the weight is high.

Dummy: Made of pipe (usually one size smaller than the pipe) and is used in horizontal pipes or at the elbow to control vertical force.

Trunnion: Also made of pipe and is welded to vertical pipes to control the weight of the pipe. Trunnion is also used as an intermediary to guide the pipe in vertical lines.

Support without intermediary parts: Often, pipes sit directly on beams or structures without any intermediaries.

A weight support that is in the form of a Hanger is a rod. This support only resists tension, and its connection point is from the top of the pipe. An important point about these supports is that they are not suitable for compressive forces and the displacement of the pipe should not cause an angle change of more than 4 ± degrees in the vertical axis of the rod.

Pipe Clip: One of the components observed in Rod Hanger supports is Pipe Clip, which is selected based on the size of the pipe and the load it must bear. Two main types are those with two screws and those with three screws, with the latter used for pipes with insulation thickness greater than 1 inch (25 mm).

Rigid Restraints

The function of these restraints is to resist weight forces, displacements caused by heat, external forces such as wind and earthquakes, etc. These restraints can be made from simple shapes of structural steel such as channels, angles, or beams, or from complex shapes like Rigid struts. The selection of each will be based on the force or moment values and the limitations required to control displacements.

One of the most common restraints is U-Bolts, which are made by shaping a rod. This restraint resists pipe displacements in two directions and its shear capacity is generally much lower than its tensile capacity. U-Bolts are usually used when lateral forces are low (as Guides), but depending on the arrangement of U-Bolt nuts, they can also be used as Anchors for low forces and small sizes.

When lateral forces exceed the permissible values of U-Bolts, strap restraints can be used, and if they are significantly higher than the mentioned range, structural steels can be used.

Rigid restraints without intermediary parts: Rigid restraints are sometimes directly made with structural steel, but sometimes an intermediary connection is also used to restrain the forces.

Using intermediary connections can provide the necessary limitations in all directions of the coordinate axes. Types of these intermediary connections include Bearing Lugs, Shear Lugs, Trunnion, and Dummy.

As previously mentioned, Bearing Lugs are used to transfer lateral forces to the main restraints, and Shear Lugs are used to prevent axial movements of the pipe. The intermediary connections Trunnion and Dummy, which are made of pipe, are used to restrain lateral or axial loads on the main pipe. If such intermediary connections are used to limit translational and rotational movements of the pipe in all directions of the coordinate axes, they are called Anchors.

Rigid Strut is also one of the restraints that controls force in one direction. This restraint includes an adjustable middle pipe during installation, where increasing the length reduces its allowable load. This restraint has a limitation on the angle change in the restraint axis, which is approximately 4 ± degrees.

Dynamic Restraints

Among the dynamic restraints are Snubber, Shock Absorber, and Springs.

Snubber (Shock Absorber) is one of the restraints that changes length during slow displacements but acts as a rigid restraint in sudden forces and loads, and it should never be used to support the weight of the piping system.

Springs are also one of the dynamic restraints that have elastic performance and are used in slow displacements.

Sway Brace

This restraint is used to control vibrations and absorb impact forces or sometimes resist displacements caused by heat. This restraint is very suitable for cases where precise control of the desired impact force is not necessary. These restraints increase the natural frequency of the system, thereby reducing dynamic force.

Final Words

Solving unique design problems is used in every structure. Clause 321.1.1 of the ASME B 31.3 piping standard suggests using specialized restraint elements to prevent potential hazards and accidents in design. Similarly, special restraints can be used to solve challenges in the execution of design and the creative implementation of plans; however, for the use of any of these special components, it is essential to consult experts. Who would you prefer to consult for advice?

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