A Comprehensive Guide to Types of Supports for Vessels

Vessels, ranging from storage tanks to pressure vessels, play a pivotal role in various industries, ensuring the safe containment and transport of liquids and gases. The structural integrity of these vessels is paramount, and their stability relies heavily on the types of supports employed. In this article, we delve into the world of vessel supports, exploring different types, their applications, and the engineering principles behind their selection.

The design and construction of vessels demand a meticulous consideration of support systems. Proper support not only ensures the structural stability of the vessel but also influences its longevity and performance.

There are four types of supports commonly used.

Skirt Supports

Skirt supports are cylindrical shells that encircle the vessel, providing support at the bottom. They are commonly used for large and heavy vessels requiring exceptional stability, particularly in applications involving high temperatures or pressures. Vessel skirt supports serve multiple functions in ensuring the stability and longevity of pressure vessels and storage tanks. They play a pivotal role in preventing excessive deflection, managing loads, and resisting external forces such as wind and seismic loads. The design and implementation of skirt supports are integral to the overall structural performance of the vessel.

Types of Vessel Skirt Supports

Vessel skirt supports come in various configurations, each tailored to specific applications and engineering requirements.

a. Structural Skirt Support: This type of skirt support is directly integrated into the vessel’s structure, forming a continuous extension of the shell. It provides robust support and is commonly used in applications where the vessel requires additional reinforcement against external forces.

b. Ring Skirt Support: The ring skirt support involves the use of a circular ring attached to the vessel’s bottom, providing support around the circumference. This configuration is particularly effective in distributing loads evenly and enhancing the vessel’s stability.

c. Bracketed Skirt Support: Bracketed skirt supports involve the use of brackets or braces to connect the vessel to the skirt, enhancing lateral stability. This type is often employed in situations where the vessel experiences lateral loads or requires additional support against tipping.

Skirt supports offer several advantages over other types of vessel supports:

Excellent stability and load distribution: The cylindrical shape of the skirt evenly distributes the vessel’s weight, ensuring excellent stability. This is especially important for tall, slender vessels that are susceptible to tipping.
Suitable for large and heavy vessels: Skirt supports can handle the significant weight and loads associated with large vessels. They are ideal for vessels too heavy for other support types.
Ideal for high-pressure and high-temperature applications: Skirt supports can be constructed from materials resistant to high pressures and temperatures, making them suitable for demanding environments.
Improved thermal expansion and contraction: Compared to other support types, skirt supports offer greater flexibility to accommodate thermal expansion and contraction, reducing stress on the vessel.

However, skirt supports also have some disadvantages:

More expensive than other support types: The material and fabrication costs of skirt supports are typically higher compared to other support options.
Installation and maintenance can be complex: Installing and maintaining skirt supports can be more challenging due to their size and weight. Specialized equipment and expertise might be required.
Limited flexibility for thermal expansion and contraction: While they offer better flexibility than some other support types, skirt supports still pose some limitations for extreme temperature fluctuations.

Applications of Vessel Skirt Supports

Vessel skirt supports are used in various applications, including:

Distillation columns: These tall, slender columns require stable support to handle the heavy internal components and process fluids.
Absorption columns: Similar to distillation columns, absorption columns also benefit from the stability offered by skirt supports.
Pressure vessels: For vessels operating under high pressure, skirt supports provide reliable support and prevent deformation.
Storage tanks: Large storage tanks holding liquids or gases often utilize skirt supports for stability and load distribution.
Offshore platforms: Vessel skirt supports are crucial for offshore platforms, ensuring stability in challenging marine environments.

Bracket or Lug Supports

Vessel bracket or lug supports provide a simple yet effective solution for supporting smaller vessels, primarily vertical ones. They consist of L-shaped structures (brackets) or welded lugs attached directly to the vessel’s side, offering support from below. Unlike other support types, they are typically used for vessels with:

Height-to-diameter ratios between 2:1 and 3:1
Operating temperatures below 750°F (400°C)
Moderate weight and pressure loads

Types of Bracket or Lug Supports

Bracket or lug supports come in different configurations, each tailored to specific applications and engineering requirements.

a. Ring Lug Supports: Ring lug supports involve the use of a circular ring, often welded to the vessel’s shell. This type of support enhances the vessel’s stability and is effective in distributing loads evenly around the circumference. Ring lug supports are commonly employed in large cylindrical vessels.

b. Bracketed Lug Supports: Bracketed lug supports use brackets or braces to connect the vessel to a supporting structure. This type of support is particularly useful in situations where lateral stability is crucial, providing additional reinforcement against forces that could cause the vessel to tip.

Advantages of Bracket or Lug Supports:

Cost-effective: They are significantly cheaper to fabricate and install than other support options like skirt or saddle supports.
Easy to install and maintain: Their simple design allows for straightforward installation and maintenance, minimizing downtime and maintenance costs.
Compact and space-saving: Their compact design makes them suitable for installations where space is limited.
Flexible for thermal expansion: They offer some flexibility to accommodate thermal expansion and contraction, reducing stress on the vessel.

Disadvantages of Bracket or Lug Supports:

Limited load-bearing capacity: They are not suitable for large or heavy vessels or those experiencing high-pressure or high-temperature conditions.
Prone to bending under excessive loads: If subjected to loads exceeding their design capacity, they can bend, compromising the vessel’s stability.
Not ideal for elevated temperatures: At temperatures above 750°F (400°C), the material strength of the bracket or lug can be compromised, leading to potential failure.

Applications of Bracket or Lug Supports:

Distillation columns: Smaller distillation columns can utilize bracket or lug supports for efficient and cost-effective support.
Heat exchangers: Heat exchangers commonly employ bracket or lug supports due to their compact design and ease of installation.
Storage tanks: Smaller storage tanks containing liquids or gases can benefit from the practical and affordable support provided by brackets or lugs.
Process vessels: Many process vessels within chemical plants or refineries utilize bracket or lug supports for their moderate weight and size compatibility.
Offshore platforms: Depending on the size and weight of the vessel, bracket or lug supports can be utilized for certain applications on offshore platforms.

Saddle Supports

Saddle supports are U-shaped structures that cradle the vessel from below, providing support along its length. They are the primary choice for horizontal vessels, offering excellent stability and distribution of weight.

Types of Saddle Supports

Vessel saddle supports come in different configurations, each tailored to specific applications and engineering requirements.

a. Full Saddle Support: A full saddle support consists of a complete circular structure that cradles the entire circumference of the vessel. This design is effective in distributing the load uniformly and is commonly used in applications where the vessel requires robust lateral support.

b. Half Saddle Support: In situations where access to the bottom of the vessel is required, a half saddle support is employed. This design allows for easy maintenance and inspection while still providing significant support to the vessel.

Advantages of Saddle Supports:

Excellent stability and load distribution: The U-shaped design provides superior stability and distributes the weight of the vessel evenly, preventing deformation and stress.
Suitable for various vessel sizes and weights: Saddle supports can be used for a wide range of vessel sizes and weights, making them a versatile solution.
Easy to install and maintain: Their straightforward design allows for simple installation and maintenance, minimizing downtime and labor costs.
Accommodates thermal expansion and contraction: Saddle supports offer some flexibility to accommodate thermal expansion and contraction, reducing stress on the vessel.

Disadvantages of Saddle Supports:

Not ideal for vertical vessels: Their design is primarily suited for horizontal vessels and may not offer adequate support for vertical ones.
May require additional structural support for larger vessels: For exceptionally large or heavy vessels, additional support structures like legs or braces might be necessary.
Limited access to the vessel’s underside: The U-shaped design can limit access to the vessel’s underside, which can be inconvenient for maintenance or inspection purposes.

Leg Supports

Vessel leg supports are individual supports attached directly to the bottom of the vessel, offering vertical support. They are commonly utilized for vertical vessels, particularly in situations requiring:

Elevated positioning: Legs raise the vessel, allowing for access to its underside, facilitating maintenance and inspection.
Clearance underneath the vessel: Legs provide space for piping, equipment, or other components located beneath the vessel.
Stability for tall and slender vessels: Legs offer sturdy support for tall, slender vessels susceptible to tipping due to their height-to-diameter ratio.

Types of Vessel Leg Supports

Vessel leg supports come in various configurations, each tailored to specific applications and engineering requirements.

a. Individual Leg Supports: In this configuration, each leg is a separate support structure. Individual leg supports are commonly used for smaller vessels or situations where flexibility in placement is required.

b. Skirt Leg Supports: Skirt leg supports involve a continuous skirt around the circumference of the vessel, with legs extending downward. This design provides additional lateral stability and is often used in larger vessels.

Advantages of Vessel Leg Supports:

Excellent stability and load distribution: Individual legs provide strong vertical support, ensuring the stability of the vessel.
Allows for easy access to the vessel’s underside: The elevated position created by the legs facilitates access for maintenance, inspection, and cleaning.
Suitable for elevated positioning: Legs can raise the vessel to a desired height, accommodating specific operational requirements.
Ideal for tall and slender vessels: Legs offer robust support, preventing tipping or swaying of tall, slender vessels.

Disadvantages of Vessel Leg Supports:

May require additional bracing for lateral stability: While providing excellent vertical support, legs might require additional bracing to address lateral loads and prevent swaying.
Not ideal for vessels with limited clearance underneath: The height created by the legs can be problematic if space underneath the vessel is limited.
Prone to damage from impacts with the ground: The exposed nature of the legs makes them vulnerable to damage from contact with objects or the ground.

Choosing the Right Type of Vessel Support

Choosing the best type of support for your vessel requires careful consideration of several factors, including:

Vessel size and weight: Larger and heavier vessels require more robust support systems like skirt or leg supports.
Vessel shape: Horizontal vessels benefit from saddle supports, while vertical vessels necessitate leg or skirt supports.
Operating conditions: High-pressure and high-temperature environments may require specialized materials and support designs.
Environmental factors: Seismic activity, wind loads, and corrosive environments necessitate specific support system adaptations.
Cost and budget: Different support types have varying costs, so finding the balance between performance and budget is crucial.

← Previous Post

Industrial Mechanical

Pages