When specifying components for industrial piping projects, understanding PN flanges is crucial for safety, performance, and global compliance. These standardized components form the backbone of countless systems across industries worldwide.
PN Definition
PN, or Pressure Nominal, is defined in standards like EN 1333 and EN 1092-1. A PN 16 flange, for example, is designed to withstand a maximum allowable working pressure (MAWP) of 16 bar at 20°C (68°F) with water as the medium.
Temperature De-rating is the key scientific principle. As temperature increases, the strength of the flange material decreases. Therefore, the actual allowable pressure drops at higher temperatures. A PN 16 flange might only be rated for 14 bar at 100°C, or 10 bar at 200°C, depending on the material.
PN vs. ANSI Class
Understanding the difference is crucial for global tenders and equipment interoperability.
| Feature | PN System (EN / DIN) | ANSI/ASME System (Class) |
| Standard | EN 1092-1, DIN 2635 etc. | ANSI B16.5, ASME B16.47 |
| Primary Units | Bar (Metric) | PSI (Imperial) |
| Common Ratings | PN 6, 10, 16, 25, 40, 63, 100 | Class 150, 300, 600, 900, 1500 |
| Pressure Basis | Pressure at 20°C | Pressure at ~38°C to 538°C depending on class |
| Gasket Seating | Considered differently in design | Integral part of the pressure rating |
| Key Takeaway | Temperature explicitly defines safe pressure. | Pressure rating is based on a material group at high temperatures. |
Common PN Ratings
| PN Rating | Max Working Pressure (bar) | Typical Applications |
| PN6 | 6 | Low-pressure water or air pipelines |
| PN10 | 10 | Domestic water, HVAC systems |
| PN16 | 16 | Industrial piping, steam lines |
| PN25 | 25 | Chemical, petrochemical systems |
| PN40 | 40 | High-pressure steam or oil pipelines |
PN Flange Types
Long tapered hub provides strong mechanical support and reduces stress concentration. Ideal for high-pressure pipelines.
Pipe slides into the flange; easier installation but lower pressure rating than WN flange.
Used to close the end of a pipeline. Strong and safe for pressure sealing.
Used with a stub end and are ideal for systems where disassembly or realignment is frequent.
Socket Weld(SW) & Threaded(TH) Flanges
Suitable for small diameter pipelines, precise alignment, and easier assembly.
Face Types
•Raised Face (RF)
•Flat Face (FF)
•Ring Type Joint (RTJ)
Flange Selection
Carbon Steel: P250GH, P265GH, C22.8 – For general services.
Stainless Steel: 304, 304L, 316, 316L – For corrosion resistance.
Alloy Steel: ASTM A182 F11, F22, F91 – For high-temperature steam.
Duplex/Super Duplex: 2205, 2507 – For aggressive offshore & chemical environments.
Conclusion
PN flanges are versatile, reliable, and globally recognized for pressure-rated pipeline connections. With a wide range of types, materials, and PN ratings, they can be customized for specific industrial needs.
We are professional in manufacturing and exporting flanges in various materials.
