What factors need to be considered in the design of pressure vessels?

I. Pressure and Temperature

Pressure: The design pressure must be greater than or equal to the working pressure. The opening pressure of safety valves or the burst pressure of rupture discs must also be considered. For example, the design pressure of a liquefied gas container should be determined based on the saturated vapor pressure at 50℃.

Temperature: The design temperature is taken as the average temperature of the metal cross-section; the material must withstand this temperature.

II. Material Selection

Mechanical Properties: Strength and toughness must meet standards.

Corrosion Resistance: The corrosiveness of the medium is crucial.

Manufacturability: Welding and forming should be convenient.

III. Structural Design

Flange Type: Flat-face flanges are suitable for low pressure, while weld neck flanges withstand high pressure.

Sealing System: Gaskets and sealing surfaces must match; raised face flanges are universal, while recessed face flanges prevent blowout.

IV. Load Analysis

Internal and External Pressure: The maximum pressure difference cannot be ignored.

Additional Loads: The equipment's own weight, wind load, and seismic loads must all be taken into account.

V. Safety Devices

Pressure Relief Devices: Safety valves and rupture discs must be selected according to standards.

Test Pressure: Sufficient margin must be allowed for the hydrostatic test pressure.

VI. Design Guidelines

Strength: Elasticity, plasticity, and burst failure must all be considered.

Stiffness: Displacement must not exceed limits.

Stability: External pressure vessels must be protected against instability.

VII. Manufacturing and Inspection

Process: Welding and heat treatment must be standardized.

Inspection: Non-destructive testing and pressure testing are essential.

VIII. Economy

Cost: A balance must be struck between materials and processes.

Maintenance: Easy access to future maintenance is required.