What type of construction is used for shells with high design pressures?

Multi-layer construction is utilized for shells with high design pressures because it enhances the structural integrity and resistance to pressure and temperature fluctuations. This method involves the use of multiple layers of material, which can improve the load-bearing capacity of the vessel. Each layer can be tailored to address specific performance requirements, such as strength, thermal resistance, and corrosion protection.

In high-pressure applications, the ability to distribute stress across different layers is crucial for maintaining safety and performance standards. Multi-layer construction allows engineers to optimize the materials and design to achieve the necessary thickness and properties without relying on a single material that might not perform as well under extreme conditions. This approach can also reduce the overall weight of the vessel while still maintaining the required strength.

Other construction types, while useful in various applications, may not provide the same level of reliability and safety needed for high-pressure vessels. Single-layer construction may not suffice under significant pressure due to potential weaknesses. Foam-filled construction offers thermal insulation but does not inherently provide the structural strength required for pressure retention. Composite construction can be effective in many scenarios, but the term is broad and may not specifically address the high design pressures as thoroughly as multi-layer construction.