Product Knowledge: What Are Flange Standards?

In piping connections and fluid transmission engineering, flanges are one of the most common connection methods. By bolting two pipe sections, valves, or other equipment together, flanges ensure system sealing while allowing easy disassembly and maintenance. Different regions, industries, and applications have varying requirements for flange standards and dimensions, so understanding flange standards is essential for piping engineers.

1. Common Flange Standards

1. ANSI/ASME Standard (USA)
   The most common is ANSI B16.5, covering steel flanges from 1/2 inch to 24 inches with pressure ratings from Class 150 to Class 2500.

2. DIN Standard (Germany)
   Widely used in Europe, with common pressure ratings of PN10, PN16, PN25, PN40, and pipe dimensions in metric units.

3. EN Standard (European Standard)
   EN1092 is the unified EU flange standard, gradually replacing DIN, and is increasingly adopted in international projects.

4. GB Standard (China)
   The Chinese national standard GB/T9112-9131 covers various pressure and dimension ranges, widely applied in domestic projects.

5. JIS Standard (Japan)
   The Japanese Industrial Standard, commonly used in Asia, with pressure ratings such as 5K, 10K, 20K.

2. Differences Between Flange Standards

• Dimensional Differences: Even for the same nominal diameter, the outer diameter, number of bolt holes, and hole size may differ, making them incompatible.

• Pressure Ratings: For example, ANSI Class 150 flanges are roughly equivalent to PN20, while DIN PN16 flanges are closer to 16 bar. This must be considered carefully during selection.

• Application Scenarios: International projects often involve multiple standards, requiring careful conversion during procurement and design.

3. Importance of Flange Standards

• Ensures Interchangeability: Unified standards allow flanges from different manufacturers to fit together.

• Guarantees Safety: Different pressure classes correspond to different load capacities; improper use may cause leaks or accidents.

• Facilitates International Projects: Global projects require compatibility across standards, so engineers must understand these differences.

4. Key Considerations When Selecting Flanges

1. Confirm which standard is required (ANSI, DIN, GB, etc.).

2. Select the proper pressure rating according to medium pressure and temperature.

3. Check dimensions carefully to avoid mismatching with the pipeline system.

4. Consider material options (carbon steel, stainless steel, alloy steel, etc.) based on the working conditions.