STRUT
What are Struts?
Struts are structural components used to resist axial forces. Piping systems are employed as a form of rigid support that can absorb compressive and tensile loads. Struts typically provide lateral or axial restraint to a pipe, preventing excessive movement or vibration caused by external loads such as thermal expansion, fluid flow dynamics, and external forces like wind or seismic activity.
Struts are used if there is no beam or structure around the point where you must restrain the line (as a guide or stopper) due to thermal expansion. The different sizes of the struts (up to 6000mm and 350 kN nominal load) help you restrain the piping line and reduce the structural requirement and, therefore, cost. Struts can be used for any load types, including the occasional loads.
Rigid Strut
As you can see, the strut is used as a stopper. The attached beam is far from the point where the stopper is required.
Key components of a typical strut system include:
Pipe clamps or lugs to secure the strut to the pipe.
Adjustable rod or brace for precise alignment and length adjustment.
End connections (welded, bolted, or clamped) that attach the strut to structural elements or steel members.
Applications of Struts in Piping Support
Control of Thermal Expansion Thermal expansion in piping systems can cause significant movement, leading to excessive stress in pipes, joints, and equipment connections. Struts are often used in conjunction with other supports, such as spring hangers or guides, to limit the movement of pipes due to temperature changes. They can be installed to absorb tensile forces during pipe elongation and compressive forces during contraction.
Vibration Damping Piping systems in industrial plants, such as power plants, chemical refineries, or oil and gas facilities, often experience vibrations from pumps, compressors, and fluid flow. Struts can be designed to dampen these vibrations and reduce the risk of fatigue failure in pipes. By rigidly securing sections of the piping, struts help maintain alignment and prevent excessive oscillations.
Wind and Seismic Load Resistance In outdoor piping installations or seismic zones, struts are commonly used to provide lateral restraint, ensuring that the pipe remains secure during wind gusts or seismic events. In such cases, the strut’s role is to prevent excessive displacement that could lead to structural damage or even catastrophic failure of the system.
Dynamic Load Support Industrial systems subject to transient forces (such as rapid valve closure or flow surges) benefit from the installation of struts to provide additional stiffness and prevent large pipe movements. In situations where snubbers or shock absorbers are used to mitigate dynamic forces, struts can provide the necessary rigidity and act as a permanent solution for repeated dynamic loads.
Types of Struts
There are different configurations of struts based on the specific requirements of the piping system:
Rigid Struts: These provide fixed axial or lateral restraint to the pipe, offering high stiffness. They are typically used where thermal movement is minimal, and the main concern is the prevention of vibration or dynamic displacement.
Adjustable Struts: These are designed with adjustable lengths to accommodate changes in pipe positions or design modifications during installation. Adjustable struts offer flexibility and ease of installation and are often used in areas where the exact location of support needs to be refined on-site.
Pre-Loaded Struts: These are used in applications where pre-loading the strut ensures that the system remains in tension or compression to prevent movement from thermal expansion or dynamic loads. Pre-loading improves the overall rigidity of the support system.
Design Considerations for Struts in Piping Systems
When designing and selecting struts for piping support, several factors must be considered to ensure the effective and safe operation of the system:
Load Capacity: The strut must be capable of handling the applied loads without yielding or failing. This includes both static loads (due to the weight of the pipe and its contents) and dynamic loads (such as vibrations or surge forces).
Pipe Material and Temperature: The material of the pipe and the operating temperature play a critical role in determining the required support. High-temperature piping may require more flexible support to accommodate thermal expansion, whereas low-temperature pipes may need more rigid restraints to prevent contraction.
Installation Environment: Whether the piping is installed indoors or outdoors, exposed to the elements, or subject to seismic forces, the installation environment determines the type of strut and its material. Corrosion resistance, for example, is essential for outdoor applications.
Anchor Points: The structural elements to which the struts are anchored must be capable of resisting the forces transmitted by the strut. Proper design ensures that the strut remains effective throughout the operation and does not introduce undue stress on surrounding structures.
Advantages of Using Struts in Piping Systems
Increased Stability: Struts provide robust support, ensuring the stability of the piping system under a wide range of operating conditions.
Vibration Control: Struts are effective at mitigating vibrations, which reduces the likelihood of fatigue and extends the lifespan of the piping system.
Versatility: Available in different configurations and materials, struts can be adapted to various piping applications, from small-diameter lines to large industrial pipelines.
Cost-Effective: Compared to more complex support systems, struts are relatively simple to install and maintain, providing an economical solution for many industrial applications. Because you will not require any additional structural steel at the attachment point of the struts. Also there is almos zero maintenance requirement.
Conclusion
Struts are essential components in industrial piping systems, providing vital support to control thermal expansion, dampen vibrations, and resist external forces. Proper design, selection, and installation of struts ensure the integrity and safety of piping systems, making them a reliable and cost-effective option for both static and dynamic support requirements. In any piping system, the use of struts should be carefully considered as part of a comprehensive piping support strategy, tailored to the unique demands of the system.
By understanding the role and application of struts, engineers and designers can optimize their piping systems to achieve safe, efficient, and long-lasting operations.
This blog is intended as a guide to determining the minimum safe spacing of plants and equipment in Oil Refineries, Petrochemical Complexes, and similar installations.
The spacing recommendations will apply in the absence of Clients' standards or supplement such standards where necessary. They are based on current industry practice.
The spacing recommendations aim to ensure that available plot areas are used economically without affecting personnel safety or plant vulnerability.