What are the common pressure ratings for flanges?

The common pressure ratings for flanges include 150 lb (150#), 300 lb (300#), 600 lb (600#), 900 lb (900#), 1500 lb (1500#), and 2500 lb (2500#). Here are the distinctions and applications for each grade:

1. 150 lb (150#):
   • Distinction: This is the lowest pressure rating, typically used for low-pressure systems with a maximum working pressure of around 150 pounds per square inch (psi) or 10.3 bar.
   • Applications: Commonly found in water supply, air systems, low-pressure steam, and general industrial applications.
     
2. 300 lb (300#):
   • Distinction: Designed for moderate-pressure systems, with a maximum working pressure of up to 300 psi or about 20.7 bar.
   • Applications: Used in general industrial applications, refrigeration, HVAC, and heating systems.
     
3. 600 lb (600#):
   • Distinction: Intended for higher-pressure systems, typically with a maximum working pressure of up to 600 psi or around 41.4 bar.
   • Applications: Commonly employed in applications such as oil and gas transmission, chemical industries, and high-temperature high-pressure steam systems.
     
4. 900 lb (900#):
   • Distinction: Suitable for higher-pressure systems, generally with a maximum working pressure of up to 900 psi or 62.1 bar.
   • Applications: Used in high-pressure steam, petroleum refining, chemical, power generation, and more.
     
5. 1500 lb (1500#):
   • Distinction: This is a high-pressure rating, typically with a maximum working pressure of up to 1500 psi or approximately 103.4 bar.
   • Applications: Found in high-pressure gas pipelines, high-temperature high-pressure boilers, and chemical process systems.
     
6. 2500 lb (2500#):
   • Distinction: This is an extremely high-pressure rating, usually with a maximum working pressure of up to 2500 psi or around 172.4 bar.
   • Applications: Used in extremely high-pressure gas and liquid pipelines, high-temperature high-pressure furnaces, and critical applications.

When selecting a flange pressure rating, it’s essential to consider the working pressure, temperature, and the nature of the transported media in the system. Different flange ratings ensure the safety and reliability of the system while also helping engineers meet the specific requirements of their applications.