Pressure vessels are integral to various industries—from power generation and oil refining to food processing and pharmaceuticals. These containers are designed to hold gases or liquids at pressures significantly different from ambient pressure, making them crucial for safe and efficient industrial operations.

In this blog, we’ll explore what pressure vessels are, how they are classified and designed, and why they are critical to modern industrial infrastructure.

What is a Pressure Vessel?

A pressure vessel is a closed container built to hold gases or liquids under pressure. Depending on the application, it may operate under high internal or external pressure, and is designed with strict safety protocols to withstand extreme conditions without failure.

Examples include:

• Boilers

• Reactors

• Storage tanks

• Heat exchangers

• Autoclaves

How Do Pressure Vessels Work?

Pressure vessels operate by containing substances under pressure safely within a robust structural envelope. This pressure may be generated:

• Internally (e.g., from a chemical reaction or compressed gas)

• Externally (e.g., vacuum vessels where the internal pressure is lower than the external)

These vessels must be designed to prevent rupture or leaks, which could result in explosions, chemical exposure, or environmental damage.

Types of Pressure Vessels

1. Storage Vessels

   • Store gases or liquids at high pressure (e.g., LPG, ammonia, nitrogen).

2. Heat Exchangers

   • Transfer heat between fluids while keeping them separated.

3. Process Vessels

   • Used in mixing, separation, or chemical reactions (e.g., reactors, distillation columns).

4. Boilers

   • Generate steam under pressure for power plants and heating systems.

Materials Used

The choice of material depends on the pressure, temperature, and corrosiveness of the contents. Common materials include:

• Carbon steel

• Stainless steel

• Nickel alloys

• Titanium

• Composite materials (for lightweight applications)

Design Standards and Codes

Due to the hazards involved, pressure vessels must comply with stringent design codes. The most widely adopted standards include:

• ASME Boiler and Pressure Vessel Code (BPVC) – USA

• EN 13445 – Europe

• PED (Pressure Equipment Directive) – EU compliance

• IS 2825 – India

These codes define parameters such as:

• Wall thickness

• Maximum allowable working pressure (MAWP)

• Safety factor

• Weld quality

• Non-destructive testing (NDT)

Common Shapes of Pressure Vessels

• Cylindrical (horizontal or vertical) – Most common

• Spherical – Used for high-pressure storage due to even stress distribution

• Conical or custom – Based on specific applications

Safety Features

• Pressure relief valves

• Burst discs

• Safety interlocks

• Regular inspection and certification

• Corrosion protection (coatings, linings)

Applications of Pressure Vessels

• Oil & Gas: Separation tanks, gas scrubbers, and storage vessels.

• Chemical Processing: Reactors and mixing chambers.

• Power Plants: Boilers and steam drums.

• Pharmaceutical: Sterilization vessels and bioreactors.

• Food & Beverage: Fermenters, autoclaves, and pressurized cooking equipment.

Risks and Failures

Pressure vessel failure can result in catastrophic outcomes. Common causes include:

• Design flaws

• Corrosion and material fatigue

• Improper maintenance

• Welding defects

• Overpressurization

Routine inspection, proper design certification, and adherence to standards are essential to avoid such incidents.

Conclusion

Pressure vessels are among the most critical yet hazardous components in many industrial systems. Their ability to safely contain pressurized materials enables everything from energy production to advanced manufacturing. With the right materials, design, and safety practices, pressure vessels can operate safely and reliably for decades.