In industrial piping, a flange’s pressure rating is critical. PN16 is one of the most common. This guide explains what PN16 means and provides the key dimensions you need for specification and compatibility.
What Does PN16 Mean?
PN stands for “Pressure Nominal.” A PN16 flange is designed to withstand a maximum pressure of 16 bar at a specified reference temperature (usually 20°C). In the older metric system (DIN/BS4504), PN16 was a standard rating. Today, it is covered by the European standard EN 1092-1.
It’s important to know that a PN16 flange is roughly equivalent to an ANSI Class 150 flange in terms of pressure handling capacity. However, their dimensions are not identical and they are generally not directly interchangeable without verification.
Key PN16 Flange Dimensions (EN 1092-1 Standard)
Dimensions for PN16 flanges are standardized under EN 1092-1. All measurements are in millimeters (mm). The table below lists the essential dimensions for a range of common sizes. These are the critical measurements for ensuring a proper bolt-up connection.
| DN | Flange OD (D) | Bolt Circle (K) | # of Bolts | Bolt Size | Bolt Hole (L) | Thickness (C2 for Weld Neck) |
| 50 | 165 mm | 125 mm | 4 | M16 | 18 mm | 18 mm |
| 80 | 200 mm | 160 mm | 8 | M16 | 18 mm | 20 mm |
| 100 | 220 mm | 180 mm | 8 | M16 | 18 mm | 20 mm |
| 150 | 285 mm | 240 mm | 8 | M20 | 22 mm | 22 mm |
| 200 | 340 mm | 295 mm | 12 | M20 | 22 mm | 24 mm |
| 250 | 405 mm | 355 mm | 12 | M24 | 26 mm | 26 mm |
| 300 | 460 mm | 410 mm | 12 | M24 | 26 mm | 28 mm |
| 400 | 580 mm | 525 mm | 16 | M27 | 30 mm | 32 mm |
| 500 | 715 mm | 650 mm | 20 | M30 | 33 mm | 44 mm |
*Key: DN = Nominal Diameter (e.g., DN50 is for a 50mm pipe), OD = Outside Diameter.*
Note: Thickness (C2) shown is for weld neck and boss flanges; plate flanges (C1) may differ.
Understanding the Standards and Flange Types
The PN16 rating is part of the European metric flange system, governed by EN 1092-1. This standard superseded older ones like DIN 2501 and BS4504. A complete flange designation includes its type and facing. For example, “EN 1092-1/01B/DN150/PN16” specifies a Type 01 (plate) flange with a Form B (raised) face.
When you see “PN16 Class 150,” it refers to a flange that meets the dimensional requirements of the PN16 standard but is being compared to the similar pressure capacity of an ANSI Class 150 flange.
Frequently Asked Questions
Q: Are PN16 and ANSI Class 150 flanges interchangeable?
A: Not directly. While they handle similar pressures, their bolt patterns, diameters, and dimensions are different. You cannot blindly substitute one for the other. They belong to two different measurement systems (metric vs. inch).
Q: What does the “PN” number actually guarantee?
A: The PN rating indicates the maximum allowable pressure in bars at 20°C. It is a “class” designation. A key point is that PN ratings (like 6, 10, 16, 25) do not scale proportionally with pressure capacity, unlike ANSI class numbers (150, 300, 600) which do.
Q: I have an old PN16 flange. What standard does it follow?
A: Older PN16 flanges were likely manufactured to DIN 2501 or BS4504 standards. The modern, directly equivalent standard is EN 1092-1. The core dimensions for PN16 have remained largely consistent through this evolution.
Q: Where are PN16 flanges typically used?
A: They are common in European and international water treatment, general industrial plants, and chemical processing applications where metric piping and pressure ratings around 16 bar are standard.
Conclusion
Specifying a PN16 flange requires knowing the correct Nominal Diameter (DN) and referencing the EN 1092-1 dimensional tables. While its pressure capability is similar to ANSI Class 150, it is part of a separate metric system with unique dimensions. Always confirm the exact standard and dimensions for your specific application to ensure a leak-free, safe connection.
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