Design and Support Configuration of Horizontal Pressure Vessels

Horizontal pressure vessels play a crucial role in various industries, including oil and gas, chemical processing, food manufacturing, pharmaceuticals, and water treatment. Their design and structure directly impact the equipment's safety, reliability, and operational efficiency. This article will explore the design principles, support configurations, stress analysis, material selection, process requirements, and maintenance of horizontal pressure vessels, aiming to provide comprehensive guidance for engineers and technicians.

Design Principles

The design of horizontal pressure vessels primarily relies on the operating pressure (internal or external). Key design principles and standards include:

1. Wall Thickness Determination

The wall thickness of a vessel is typically determined by analyzing the operating pressure and evaluating the material properties. It is essential to adhere to the principle of controlling circumferential stress to ensure the safety of the vessel wall under high-pressure conditions. Additionally, circumferential stability must be considered to prevent deformation or instability during operation.

2. Consideration of Additional Loads

For vessels with larger diameters, external factors such as self-weight, wind load, and seismic load must also be included in the design calculations. These additional loads can cause displacement, deformation, or damage during operation, making detailed analysis and calculations necessary in the design phase.

3. Strength and Stability Checks

After completing the design, the circumferential and axial strength, as well as stability of the vessel wall under additional loads, must be verified. This process ensures that the vessel meets both circumferential and axial strength and stiffness requirements under various operating conditions. Reliability and safety of the design are validated through calculations and simulations.

Support Configuration

The choice and design of supports are essential components of the horizontal pressure vessel structure, primarily serving to distribute and bear the vessel's load. Key considerations in support design include:

1. Use of Saddle Supports

Horizontal pressure vessels typically employ saddle supports. The structure of the saddle should be chosen based on the vessel's nominal diameter, and the design must adequately consider the angle of contact. Commonly, the angle of contact is chosen to be 120°, 135°, or 150°, which directly affects the stress distribution in the vessel at the support points.

2. Advantages of Dual Support Configuration

In many cases, a dual support configuration can distribute loads more effectively. This arrangement makes the vessel's loading conditions similar to those of a simply supported beam, helping to reduce internal bending stresses. However, for this effect to be realized, all support points must be strictly maintained on the same horizontal plane, which presents higher design requirements for large horizontal vessels.

3. Design of Movable Supports

In a dual support setup, typically, one support is fixed while the other is movable. The foundation bolt holes of the movable support should be elongated in a direction parallel to the vessel's axis to allow free movement due to thermal expansion or other reasons. This design helps reduce stress concentration caused by temperature changes, ensuring the safe and stable operation of the vessel.

Stress Analysis

Stress analysis of horizontal pressure vessels is a critical aspect of the design, focusing on the following areas.

1. Membrane Stress and Bending Stress

Membrane stress induced by operating pressure and bending stress caused by the vessel's weight, wind load, and other factors jointly affect the vessel. The design must consider both types of stress and ensure that the shell can withstand various operating conditions.

2. Multi-Point Load Distribution

In a dual saddle configuration, the stress conditions of the horizontal vessel resemble those of a simply supported beam. Internal bending stresses in a multi-point beam are usually lower; however, to ensure uniform loading at each support point, a thorough assessment of the foundation is necessary to address uneven settlement.

3. Design Calculations and Simulations

Modern engineering calculation methods, such as Finite Element Analysis (FEA), can accurately simulate the stress distribution of pressure vessels under different conditions. Such calculations help designers identify potential issues and make adjustments to ensure the safety of the vessel's design.

Material Selection and Process Requirements

The choice of materials for horizontal pressure vessels is vital for their safety, durability, and long-term performance. Common materials and selection criteria include:

1. Material Types

Choosing the right material based on operating conditions is crucial. Common materials include carbon steel, stainless steel, and alloy steel. For applications requiring corrosion resistance, materials like 304 and 316 stainless steel are preferable to extend the vessel's lifespan.

2. Welding and Fabrication Processes

Welding is a key process in manufacturing pressure vessels, as the quality of the welds directly impacts the overall strength and seal integrity of the vessel. Appropriate welding methods and materials must be used, along with necessary weld inspections, to ensure compliance with quality standards.

3. Surface Treatment

For vessels operating in special environments, surface treatment processes (such as spraying or galvanizing) are also important design considerations. These treatments can enhance the vessel's corrosion resistance and wear resistance, ensuring stable operation in harsh conditions.

Conclusion

The design and support configuration of horizontal pressure vessels is a complex and meticulous engineering task. Sound design principles, scientific stress analysis, appropriate material selection, and effective maintenance strategies are critical for ensuring the safe and stable operation of these vessels. By thoroughly understanding these factors, engineers can design horizontal pressure vessels that meet specific requirements and maintain high safety standards, thus providing solid support for efficient operations in various industries. As industrial demands evolve, continuous innovation and improvement in the design and technology of horizontal pressure vessels are necessary to meet future challenges.