API 520 is a standard published by the American Petroleum Institute (API) that provides guidelines for the sizing, selection, and installation of pressure-relieving systems. It is especially critical for pressure safety valves (PSVs) used in refineries and process plants.

API 520 is Divided into Two Parts:

Part I – Sizing and Selection

• Provides calculation methods for the accurate sizing and selection of pressure relief devices
• Includes distinct formulas for gas, steam, and liquid service
• Covers capacity calculations and the determination of appropriate valve types
  
  

Part II – Installation

• Addresses piping layout, system configuration, and the effects of back pressure
• Offers installation guidelines to ensure safe and effective operation of relief systems
  
  

Common Application Areas:

• Petroleum refineries
• Chemical processing facilities
• Power generation plants
• LPG and natural gas systems
  
  

Key Benefits:

• Provides overpressure protection for equipment and systems
• Enhances personnel and environmental safety
• Ensures regulatory and technical compliance for industrial facilities