Pressure Vessels

Each pressure vessel that we manufacture is per the American Society of Mechanical Engineers (ASME) code. As a leading ASME pressure vessels manufacturer, our specialty lies in working with a variety of alloys, pressures, & designs to meet your custom requirements. More »

Weld Overlay and Clad Vessels

Our weld overlay and clad vessels are fully code-compliant. We use our advanced welding techniques to their full capabilities to offer you the finest overlay/clad components and pressure vessels. More »

High Pressure Vessels

We hold the American Society of Mechanical Engineers (ASME) U, U2, and U3 stamps, and have the capabilities and resources to manufacture ASME high pressure vessel to your exacting specifications. More »

Autoclaves

We hold the American Society of Mechanical Engineers (ASME) U, U2, U3, PP, & S stamps, and have the capabilities and resources to manufacture autoclaves to your exacting specifications. More »

Heat Exchangers

We specialize in the design, engineering, and fabrication of Shell and Tube Heat Exchangers, including thermal calculations. All of our units are built in strict accordance with the latest edition and addenda of the A.S.M.E. Code, Section VIII Division 1, 2, or 3 and T.E.M.A.” More »

 

Understanding the Design of Two Main Types of Pressure Vessels

Generally, pressure vessels are structures used to store liquids and gases under pressure. Pressure vessels are used because they help the stored chemical maintain its normal state. Two main shapes of pressure vessels exist, spherical and cylindrical. Let us look at their design and pressure constraints. The design of the vessel is largely dependent on the pressure inside and outside the vessel. The pressure inside the vessel is attributable to the pressure exerted by the gases and liquids. The air outside exerts some amount of pressure on the vessel. This helps in making decisions related to the thickness and type of material, the method of construction, shape of the vessel, and other factors related to construction of the vessel.

All of this together contributes to the thoughtful design of pressure vessels.

Spherical Pressure Vessel

These structures are considered ideal for storage of liquids or gases under pressure. They are constructed with walls that are thinner than the radius.

The formula followed to ascertain the thickness of the walls is:

r̲ >10
t

Here, ‘r’ stands for radius of the sphere and ‘t’ is the thickness of the wall. This formula proves that the wall thickness of the vessel has to be much lesser than the radius.

Since the walls are thin, the material stored inside the vessel exerts equal amount of pressure on the surface area of the wall.

These methods are created by welding two hemispheres. The pressure allowed inside is dependent on various factors:

  • It is dependent on the tensile strength of the metal used.
  • It is dependent on the shear stress of the metal.
  • The tension in the welded seam of the sphere is also taken into account when calculating the allowable pressure.
  • These vessels are constructed in a way that the inner pressure should always greater than the external pressure.

Theoretically, a sphere is the ideal size for a pressure vessel. But it is more expensive to manufacture when compared to cylindrical pressure vessels.

Examples: Pressurized cabins, air tanks, etc.

Cylindrical Pressure Vessel

For smaller cylindrical pressure vessels, a single tube with no seams can be used. For bigger vessels, different methods are employed for the construction. Sometimes, a long steel plate is wrapped around a mandrel at an angle. The seams are then welded. Cylindrical vessels also feature hemispherical heads at the ends. To determine the pressure that this vessel can handle, we need to take into account the stress in the walls. This stress is of two types, viz. the circumferential stress and the longitudinal stress. One must also consider the stress acting on the welded seam.

Examples: Fire extinguishers, diving cylinders, distillation towers, etc.

Pressure vessels are used in various applications in everyday and professional lives. One of the most brilliant yet powerful inventions, great care should be taken care when designing, fabricating, and purchasing these vessels.

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