Pressure Vessels are containers which are designed to hold liquids, vapors, or gases at high pressures, usually above 15 psig. Examples of common pressure vessels used in the petroleum refining and chemical processing industries include, but are not limited to, storage tanks, boilers, and heat exchangers. Each individual vessel has its own operating limits built in by design that it has to work under, refered to as its design pressure and design temperature. Operating outside of these limits could damage the equipment and potentially lead to loss of containment or catastrophic failure.

Because they work under immense pressures, a ruptured pressure vessel can be incredibly dangerous, leading to poison gas leaks, fires, and even explosions. For this reason, pressure vessel safety is imperative. There are several standards and practices that cover the construction, maintenance, and inspection of pressure vessels. Chief among these standards are ASME Section VIII and API 510.

ASME Section VIII is the section of the ASME Boiler & Pressure Vessel Code (BPVC) that covers pressure vessels. It gives detailed requirements for the design, fabrication, testing, inspection, and certification of both fired and unfired pressure vessels.

API 510, "Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration" is an inspection code, written and published by the American Petroleum Institute, that covers the in-service inspection, repair, alteration, and rerating activities for pressure vessels and the pressure relieving devices protecting these vessels.

When it comes to inspections, most pressure vessels should be examined once before being placed into service and again every 5 years after every alteration or major repair. An inspection can be internal, external, or both and should involve a thorough examination, a thickness evaluation, a stress analysis, an inspection of the vessel’s pressure release valves, and a hydrostatic pressure test. It is also important to perform a surface inspection, examine the insulation and any structural connections, and finally inspect any welds or joints.

Related Topics

• Aboveground Storage Tanks (ASTs)
• Boiler Tubes
• Boilers
• Bolts
• Coker Units
• Cooling Towers
• Crude Distillation Unit (CDU)
• Deaerators
• Fired Heaters
• Fixed Equipment
• Flanges
• Flare Systems
• Furnace Tubes
• Glass-lined Equipment
• Heat Exchangers
• HF Alkylation Units
• Hydrocracking Unit
• Hydrotreater
• Piping
• Pressure Relieving Devices (PRDs)
• Rotating Equipment
• Vacuum Distillation Unit (VDU)
• Valves

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