Cogbill’s RedLineIPS Shim Block Assembly

By Hani Almufti – 10/23/2023

In the realm of above-ground piping systems in the petrochemical industry, accuracy, stability, and safety are of paramount importance. This is where shim block assemblies play a vital role as pipe supports for maintaining the integrity and functionality of piping systems and associated structural supports. Let’s delve into what shim block assemblies are, how they work, and their role in industrial piping systems.

What is a Shim Block Assembly?

Shim block assemblies are designed to provide adjustment and alignment within a piping system. Their primary purpose is to ensure that pipes and their support structures are securely held in place, correctly aligned, and adequately supported, while at the same time allow the pipe to move axially.

Pipes are often subjected to temperature fluctuations. As the temperature changes, pipes expand and contract. Allowing axial movement accommodates this expansion and contraction, preventing undue stress on the piping system and the supporting structure. This is particularly important in long pipelines and systems where expansion and contraction are significant.

Shim block assemblies are available in a diverse range of configurations and materials to suit different applications. In this discussion, we will focus on one specific type of configuration made entirely from steel. Such an assembly typically includes the following components:

1. Adjustable Support Block: This critical component consists of two bent plates supported by stiffener plates. Its unique configuration enables it to provide support to a pipe from underneath. It serves as the primary load-bearing element that holds the weight of the pipe.
2. Stiffener Plates: Four sets of stiffener plates complement the adjustable support block. They offer additional structural support and rigidity to the assembly, enhancing its ability to hold and support steel pipes and their contents. Stiffener plates contribute to the overall stability of the assembly.
3. Fastener Assemblies: The fastener assemblies, which may include all-thread rods, heavy hex nuts, washers, or other appropriate fastening mechanisms, play an important role in adjusting the height and position of the shim blocks. By either bringing the shim blocks closer together or moving them apart, these fasteners enable height adjustments, allowing for optimal alignment.
4. Base Plate: The shim block assembly is typically mounted on a base plate. This base plate is secured to the supporting structure using bolts or other suitable attachment methods. The base plate not only provides stability to the assembly but also contributes to its structural integrity. Additionally, it can be used to secure an optional hold-down clamp, enhancing the overall functionality of the assembly.
5. Optional Liners: In environments where corrosion and vibration are prevalent concerns, optional liners can be used to protect the pipes from friction and vibration. These non-corrosive liners can be applied to both the shim block assembly as well as to the inside perimeter of an optional hold-down clamp. Common liner materials include PTFE and EPDM, among others, which effectively reduce wear, mitigate friction, and dampen vibrations to ensure the longevity and reliability of the piping system.

Shim Block Assembly Installation and Operation

The installation and operation of a shim block assembly are essential for achieving pipe alignment and support within a piping system. Here’s a step-by-step guide on how the process typically works:

Initial Positioning:

• Begin by placing the base plates in the correct location and orientation to align the holes in the base plates with the corresponding holes in the supporting structure.

• Secure the base plates in place by applying and tightening bolts. These bolts are instrumental in stabilizing the assembly and ensuring its secure attachment to the supporting structure.

Shim Block Placement:

• Position the shim blocks beneath the pipes at the specific points where height adjustment is required. This step is crucial, as it determines where the pipes will be raised or lowered to achieve the desired alignment and support.

Fastener Installation:

• Utilize appropriate fasteners, such as All Thread rods or bolts, to insert them through the holes in the shim blocks. These fasteners enable you to make adjustments to the height and position of the shim blocks.

Adjustment:

• To raise or lower the pipes and attain the desired elevation, you will need to adjust the fasteners.

• Tightening the fasteners compresses the shim blocks, causing the pipes to be lifted to the desired height. It is important to perform this adjustment incrementally to achieve controlled elevation changes.

Fine-Tuning:

• The adjustability of the shim block assembly allows for fine-tuning of the height or elevation of the pipes. This is achieved by making small, controlled adjustments to the fasteners.

• Fine-tuning ensures that the pipes are well aligned and adequately supported, contributing to the overall efficiency and reliability of the piping system.

Shim Block Assembly Benefits for Piping Systems

Shim block assemblies offer a range of significant benefits for piping systems, enhancing their efficiency, longevity, and reliability. Here are some of the key advantages they provide:

1. Alignment: Alignment of pipes within a piping network is important for ensuring the efficient flow of materials. Shim block assemblies enable adjustments to achieve correct pipe alignment. This reduces stress on the piping system, promoting optimal performance and preventing issues related to misalignment.
2. Support: Shim block assemblies play an important role in providing essential support to pipes and associated structures. Operators can easily adjust the elevation and positioning of pipes, ensuring they are adequately supported and securely held in place. This support is of great importance for the structural integrity of the piping system.
3. Adjustability: These assemblies are designed with user-friendly adjustability in mind. They allow for quick modifications to the elevation and alignment of pipes. This flexibility promotes efficient operations and simplifies maintenance tasks, reducing downtime and operational disruptions.
4. Corrosion Protection, and Vibration and Noise Mitigation: When corrosion, vibration, and noise are constant concerns, shim block assemblies may include specially designed liners. These liners prevent metal-to-metal contact, reducing wear and tear. Liner materials like PTFE, EPDM, and PVC act as a protective barrier, mitigating friction, dampening vibration, and reducing noise. These liners can be attached to either the shim block assembly block, the optional hold-down clamp, or both. The use of such liners ensures the longevity and reliability of the piping system, even in harsh conditions.

Protective Liner Types

The choice of liner material depends on the specific requirements of the application and the environmental conditions. The following are common liner materials used in shim block assemblies:

PTFE (Polytetrafluoroethylene):

• PTFE is a popular choice for liners in shim block assemblies due to its excellent chemical resistance, low friction properties, and resistance to corrosion. It is highly effective in preventing metal-to-metal contact and reducing friction. PTFE is known for its non-stick properties, making it suitable for applications involving chemicals and corrosive substances.

• Neoprene: Neoprene rubber has excellent resistance to chemicals and is known for its durability. It is often used in applications where resistance to oil, heat, and chemicals is required. Neoprene liners can help mitigate vibration and noise in shim block assemblies.
• Fabreeka: Fabreeka materials are engineered to provide exceptional properties for vibration isolation and structure-borne noise control. These materials can include layers of rubber, cotton fabric, and other compounds, all meticulously designed to deliver outstanding damping characteristics. The Fabreeka Pad is renowned for its ability to absorb vibrations, protect pipes and equipment from shock and vibration, and enhance the longevity of piping systems. It’s a versatile choice for applications where vibration control is paramount, and its use can significantly reduce the potential for damage and wear on the piping system.
• Cotton Duck Pad: A “Cotton Duck Pad” is typically crafted from a robust, tightly woven cotton fabric known as cotton duck. Primarily composed of cotton fibers, it offers excellent strength and durability. It is available in different weights and thicknesses, with heavier weights being thicker and more resilient. In some cases, it may be coated with materials like PVC for added water resistance or fire-retardant coatings for enhanced safety. As a liner for pipe supports, it provides protection, cushioning, and insulation.
• UHMW (Ultra-High-Molecular-Weight Polyethylene): UHMW is a type of polyethylene known for its extremely low coefficient of friction, making it an excellent choice for reducing friction and preventing wear in shim block assemblies. It provides good protection against corrosion.
• EPDM (Ethylene Propylene Diene Monomer): EPDM is a synthetic rubber that provides good resistance to environmental factors, such as weather, ozone, and UV exposure. It also offers moderate resistance to chemicals and provides effective damping of vibrations and noise. EPDM liners are often used in outdoor or exposed environments.
• PVC (Polyvinyl Chloride): PVC is a thermoplastic material known for its corrosion resistance and versatility. PVC liners are used to create a protective barrier and reduce friction in shim block assemblies. They are suitable for applications where corrosion is a concern.
• Nitrile Rubber (NBR): Nitrile rubber is another type of synthetic rubber that offers good resistance to oil and fuels. It can be used as a liner to reduce vibration and noise in certain applications, particularly those involving lubricating oils.

The choice of liner material depends on factors such as the specific application, the type of chemicals or substances the shim block assembly will be exposed to, and the environmental conditions. It’s important to select a liner material that offers the right balance of corrosion resistance, vibration damping, and noise reduction to meet the requirements of the piping system and the surrounding environment.