Vessel Supports

Introduction

Vessel supports play a crucial role in the design of process equipment. They are responsible for maintaining the integrity and stability of vessels, ensuring their safe operation. In this topic, we will explore the design principles and considerations for different types of vessel supports, including skirt supports, lug supports, and saddle supports.

Design of Skirt Supports

Skirt supports are commonly used to provide vertical support to vessels. They are designed to withstand the weight of the vessel and the contents it holds. When designing skirt supports, several key considerations must be taken into account.

Load calculations and distribution

The first step in designing skirt supports is to determine the load that the skirt will bear. This includes the weight of the vessel, the contents, and any additional loads such as wind or seismic forces. The load must be distributed evenly to ensure uniform support.

Material selection

The material used for skirt supports should have sufficient strength and corrosion resistance. Common materials include carbon steel, stainless steel, and fiberglass-reinforced plastic (FRP). The selection of the material depends on factors such as the process conditions, the vessel's contents, and the environment.

Skirt height and diameter

The height and diameter of the skirt are determined based on the vessel's dimensions and the required support. The skirt should be tall enough to provide adequate support and prevent excessive deflection.

Skirt thickness and reinforcement

The skirt thickness is determined based on the load calculations and the material's strength. Additional reinforcement, such as stiffeners or gussets, may be required to enhance the skirt's rigidity.

To design skirt supports, follow these steps:

1. Determine the load on the skirt.
2. Select the appropriate skirt material.
3. Calculate the required skirt height and diameter.
4. Design the skirt thickness and reinforcement.

Real-world applications of skirt supports can be found in various process equipment, such as pressure vessels, storage tanks, and heat exchangers.

Design of Lug Supports

Lug supports are used to provide horizontal support to vessels. They are typically attached to the vessel's shell or head and transfer the load to the supporting structure. When designing lug supports, several key considerations must be taken into account.

Load calculations and distribution

Similar to skirt supports, the first step in designing lug supports is to determine the load that the lugs will bear. This includes the weight of the vessel, the contents, and any additional loads.

Lug size and configuration

The size and configuration of the lugs depend on factors such as the vessel's dimensions, the load distribution, and the attachment method. The lugs should be designed to distribute the load evenly and prevent stress concentrations.

Lug material and attachment

The material used for lug supports should have sufficient strength and toughness. Common materials include carbon steel, stainless steel, and alloy steels. The attachment method, such as welding or bolting, should be selected based on factors such as the load requirements and the vessel's design.

To design lug supports, follow these steps:

1. Determine the load on the lugs.
2. Select the appropriate lug size and configuration.
3. Design the lug material and attachment.

Lug supports are commonly used in vessels such as reactors, columns, and distillation towers.

Design of Saddle Supports

Saddle supports are used to provide horizontal support to cylindrical vessels. They are designed to distribute the load evenly along the vessel's circumference. When designing saddle supports, several key considerations must be taken into account.

Load calculations and distribution

The first step in designing saddle supports is to determine the load that the saddle will bear. This includes the weight of the vessel, the contents, and any additional loads.

Saddle size and configuration

The size and configuration of the saddle depend on factors such as the vessel's dimensions, the load distribution, and the attachment method. The saddle should be designed to distribute the load evenly and prevent stress concentrations.

Saddle material and attachment

The material used for saddle supports should have sufficient strength and toughness. Common materials include carbon steel, stainless steel, and alloy steels. The attachment method, such as welding or bolting, should be selected based on factors such as the load requirements and the vessel's design.

To design saddle supports, follow these steps:

1. Determine the load on the saddle.
2. Select the appropriate saddle size and configuration.
3. Design the saddle material and attachment.

Saddle supports are commonly used in cylindrical vessels such as storage tanks and horizontal pressure vessels.

Advantages and Disadvantages of Vessel Supports

Vessel supports offer several advantages in process equipment design. They provide stability and prevent excessive deflection, ensuring the safe operation of vessels. Vessel supports also facilitate maintenance activities by allowing easy access to the vessel's internals.

However, vessel supports also have some limitations. They can increase the overall weight and cost of the equipment. Additionally, improper design or installation of supports can lead to stress concentrations, fatigue failure, or excessive deformation.

When comparing different types of vessel supports, it is important to consider factors such as the vessel's geometry, load requirements, and process conditions. Skirt supports are suitable for vertical support, while lug supports are ideal for horizontal support. Saddle supports are commonly used for cylindrical vessels.

Conclusion

Vessel supports play a critical role in the design of process equipment. Skirt supports, lug supports, and saddle supports are designed to provide vertical and horizontal support to vessels, ensuring their stability and integrity. By considering factors such as load calculations, material selection, and attachment methods, engineers can design effective and reliable vessel supports. Understanding the advantages and limitations of vessel supports is essential for successful process equipment design.

In summary, the key concepts covered in this topic include:

• Importance of vessel supports in process equipment design
• Design considerations for skirt supports, lug supports, and saddle supports
• Step-by-step design process for skirt supports, lug supports, and saddle supports
• Real-world applications of vessel supports in process equipment
• Advantages and disadvantages of using vessel supports

Remember to consider the specific requirements of each vessel and consult relevant design codes and standards when designing vessel supports.

Summary

Vessel supports are crucial in process equipment design as they maintain the integrity and stability of vessels. Skirt supports provide vertical support, while lug supports offer horizontal support. Saddle supports are used for cylindrical vessels. The design considerations for each type of support include load calculations, material selection, and attachment methods. Vessel supports have advantages such as stability and easy maintenance but also limitations like increased weight and cost. Understanding the design principles and applications of vessel supports is essential for successful process equipment design.

Analogy

Imagine a tall building that needs support to stand upright. The building's foundation acts as the skirt support, distributing the weight evenly and preventing excessive deflection. The beams and columns provide lug supports, ensuring horizontal stability. Finally, the saddle supports resemble a saddle placed on a horse's back, providing support along the cylindrical shape of the vessel.