Pipe supports are essential components of piping systems. Choosing the right support type is essential for a cost effective and well performing piping system.
1. Pipe Support Design
Pipe support is one of the essential piping components that often poses significant challenges. Designers need to consider multiple factors:
- Stress Analysis: Determine if stress analysis is required for any specific lines to ensure proper support under various conditions.
- Support Spacing: Determine the optimal distance between supports, considering the weight and characteristics of the pipes.
- Support Types: Select appropriate support types based on the specific service requirements, considering factors such as temperature, pressure, and material.
- Space Constraints: Assess whether there is sufficient space for the installation of hangers, cans, and other support components.
- Horizontal Restraint: Ensure that the lines are adequately restrained in the horizontal plane to prevent undesired movement.
Addressing these considerations is crucial for the effective and reliable design of pipe support systems within piping projects.
2. Types of Pipe Supports
2.1 Pipe Racks
Structural steel pipe racks play a crucial role in supporting pipes, power cables, and instrument cable trays in various sectors such as petrochemical, chemical, and power plants. They serve as the primary infrastructure for transporting materials between equipment, storage, and utility areas. Usually mixed with storage racks in warehouses, pipe racks are specifically designed to support and organize piping systems.
The arrangement of pipes on a pipe rack are carefully considered to optimize functionality, safety, and maintenance access within a process unit.
Photo 1: Pipe Rack
Key features and characteristics of pipe racks include:
- Functionality: Pipe racks serve as the main arteries of process units, they carry process and utility piping. Additionally, they may accommodate instrument and cable trays, as well as certain mechanical equipment, vessels, and valve access platforms.
- Design Elements: Pipe racks are constructed with a series of transverse beams running along the length of the pipe system. These beams are spaced at uniform intervals, typically around 20 feet. To facilitate maintenance access beneath the pipe rack, transverse beams are often designed as moment frames. Longitudinal struts connect the transverse beams.
- Types of Pipes: Different types of pipes are arranged on the pipe rack based on their function.
- Utility pipes, such as steam, cooling water, extinguishing water, and fuel oil, are usually located in the middle or on the top level of a single-level pipe rack or the top level of a multi-level rack.
- Process pipes, carrying products involved in chemical reactions, are positioned on the outside or bottom level.
- Relief and flare pipes, serving safety purposes are typically placed on the outer edges of the rack.
2.2 Structural Supports
The analysis of pipe supports requires close coordination between piping and structural engineers. Collaboration with electrical engineers is also crucial, especially when supporting cable trays and conduits from the same steel structures as the piping. It is essential to establish clear territories at the project’s outset to prevent later interferences and to achieve a comprehensive design meeting the needs of all disciplines.
Photo 2: Structural Support
Sometimes responsibilities between piping and structural engineers may overlap. While the piping engineer typically handles trivial supports, there’s a need for collaboration on more complex supports. Several considerations for loading conditions include a corrosion allowance for steel members in harsh environments, conservative foundation design due to high modification costs, and ensuring maximum stresses in steel fall within acceptable ranges.
Additional considerations involve selecting the right paint for corrosion protection, as well as designing foundations conservatively, given their high modification costs. Qualified structural engineers are recommended for foundation design.
For stand-alone posts subjected to eccentric loads, closed sections like pipes or structural steel tubes (Hollow Structural Sections or “HSS”) are preferable, offering superior resistance to axial torque. These sections also facilitate easier painting compared to wide flange beams. Slender wide flanges used as columns have limited resistance to torque and can experience significant deflection under light loads.
2.3 Pipe Shoes
Shoes serve as common restraints, particularly for insulated pipes, allowing clearance for insulation between the pipe and support steel. They are typically made from WT4s for insulation up to 3 1/2 inches and WT6s for insulation thicknesses between 4 and 5 1/2 inches. Manufactured shoes are available with slots for accommodating insulation and jackets.
Photo 3: Pipe Shoes
To guide shoes, welding strips parallel to the sole plate are often used, providing a transverse restraint. Clips (angles) over the sole plate can further limit upward movement.
Shoes should be designed to extend over both sides of the supporting steel’s bearing surface to prevent the accumulation of dirt or water. The shoe’s length must be sufficient to prevent it from falling off the support steel, ensuring the pipe can return to its neutral position upon cool-down and avoiding potential issues.
Anchoring play a crucial role in restricting displacements in all three axes and rotation in all three axes. A basic form of anchor is the double U-bolt which may suffice for small loads. However, it’s important to note that a U-bolt provides a non-rigid connection, particularly for heavier loads, as it grasps the pipe only at the top and bottom.
More robust anchors are constructed through welding. The welded anchor offers a secure and well-supported connection.
The design possibilities for anchors are extensive and can range from simple to complex, depending on the engineer’s creativity or project economics.
Single rods can be suspended from overhead steel to support individual pipes. It’s important to note that these rods may swing when subjected to horizontal forces, and significant horizontal force can be generated if there is substantial horizontal displacement.
In practical applications, the use of rods is limited to situations where the expected angle from the vertical is less than 4°. Erection is facilitated by employing turnbuckles to connect rods with left-and right-hand threads. This simplifies the adjustment of elevation, making it easier for adjustments compared to using connecting couplings on right-hand threaded rods, which would necessitate precise cutting of the rods to the exact length.
Rollers are frequently employed in situations where significant axial growth is expected. This is commonly seen in cross-country transmission lines, especially where they traverse bridges, to prevent the transfer of expansion loads into the bridge structure. However, in industrial lines, shoes are more commonly used.
In cases of axial growth caused by thermal expansion, particularly in hot lines that require insulation, it’s essential to install a crush-proof saddle over the roller to protect the insulation. Some manufacturers offer insulated saddles, while others provide plain ones with the insulation abutting the saddle.
Novelty Steel offers pipe support fabrications for piping projects. Some reference work are;