The definition of what constitutes a pressure vessel often causes some confusion, especially when it comes to inspection and repairs. If you operate any facility that operates pressure vessels it’s important you understand the basics and know when to call in outside assistance.

What Is A Pressure Vessel

A pressure vessel is any tank or vessel that operates at a pressure above normal ambient pressure. Vessels exceeding a certain size and pressure should be built to the ASME Boiler and Pressure Vessel Code. These include vessels larger than 5 cubic feet designed to operate above 15 psi and vessels operating above 600 psi and larger than 1.5 cubic feet.

Must The Vessel Comply With Certain Standards?

Yes, any pressure vessel for use in the U.S. should conform to the requirements of the ASME Boiler and Pressure Vessel Code. It should be noted that the code itself is not mandatory except as enforced in legislation by each U.S. state. Additionally, OSHA now requires that Pressure Vessels are built according to ASME VIII.

What Are The Inspection Requirements?

Hydropneumatic tanks designed to regulate water supply must be externally inspected every four years. Other pressure vessels should be externally inspected every two years. Internal inspections of vessels and tank material may be required by the local Inspector of Record.

Who Can Inspect A Pressure Vessel?

Requirements vary from state to state, but most require that an inspector registered with The National Board of Boiler and Pressure Vessel Inspectors conducts the inspection. Alternatively, an Owner-User organization that has been accredited by the National Board of Boiler and Pressure Vessel Inspectors may inspect their own vessels.

Who Can Repair A Pressure Vessel?

An organization that has obtained a Certificate of Authorization for pressure vessel repairs from the National Board of Boiler and Pressure Vessel Inspectors is allowed to repair pressure vessels.

What Is The Purpose Of The Inspection Certificate?

The inspection certificate confirms that the pressure vessel has been inspected and is safe to operate. Most insurers and states require that users have valid inspection certificates, although some classes of pressure vessels are exempt.

Are Pressure Vessel Requirements The Same Everywhere?

No, while they are very similar, there are subtle variations within the U.S. as the legislature in each state is responsible for determining local requirements. The same applies to other North American countries whose regulations also differ slightly. Local regulations should always be consulted.