EN1092-1 is the European standard for circular steel flanges, establishing uniform specifications for dimensions, pressure-temperature ratings, materials, and manufacturing requirements. It ensures interchangeability and safe performance across different manufacturers and countries. The standard covers various flange types, with pressure ratings from PN 2.5 to PN 400, and nominal diameters from DN 10 to DN 4000.
What is EN1092-1 Weld Neck (WN) Flange?
Weld Neck Flanges, designated as Type 11 in EN1092-1, feature a long tapered neck that is butt-welded directly to the pipe. This design creates a strong, integral connection that provides excellent stress distribution and fatigue resistance. Unlike slip-on or threaded flanges, WN flanges are specifically engineered for demanding applications involving high pressure, temperature extremes, or cyclic loading conditions.
EN1092-1 WN Flange Dimensions: Reference for DN80
For the commonly used DN80 (3-inch equivalent) size, here are the key dimensions across different pressure classes:
| PN | 6 | 10 | 16 | 25 | 40 | ||
| Mating dimensions | Outside diameter D | 190 | 200 | 200 | 200 | 200 | |
| Diameter of bolt circle K | 150 | 160 | 160 | 160 | 160 | ||
| Diameter of bolt hole L | 18 | 18 | 18 | 18 | 18 | ||
| Bolting | Number | 4 | 8 | 8 | 8 | 8 | |
| Size | M16 | M16 | M16 | M16 | M16 | ||
| Outside Diameter of neck A | 88.9 | 88.9 | 88.9 | 88.9 | 88.9 | ||
| Flange thickness | C2 | 16 | 20 | 20 | 24 | 24 | |
| Length | H2 | 42 | 50 | 50 | 58 | 58 | |
| H3 | 10 | 10 | 10 | 12 | 12 | ||
| Neck diameters | N1 | 102 | 105 | 105 | 105 | 105 | |
| Corner radii | R1 | 8 | 6 | 6 | 8 | 8 | |
| Wall Thickness | S | 3.2 | |||||
Note: For complete dimension tables (including pipe OD, sealing face diameter, and weights) across all PN classes up to PN 400, refer to the official EN1092 1 standard or contact our technical team with your specific DN/PN requirement.
Advantages of EN1092-1 WN Flanges
1. Superior Strength & Fatigue Resistance
The full-penetration weld between the neck and pipe creates a joint as strong as the pipe itself, ideal for cyclic loading and high pressure service.
2. Optimized Stress Distribution
The tapered hub smoothly guides stresses away from the weld zone into the flange ring, reducing peak stress concentrations and extending service life.
3. Reliable Sealing Performance
Compatible with Raised Face (RF), Flat Face (FF), and Ring-Type Joint (RTJ) sealing surfaces. When paired with suitable gaskets (e.g., spiral-wound or ring-joint gaskets), they ensure leak-tight integrity even under thermal cycling.
4. Full DN/PN Dimensional Compliance
Follows universal Nominal Diameter (DN) and Pressure Nominal (PN) sizing, enabling seamless connection with valves, pumps, and equipment from any EN compliant supplier.
5. Ease of Inspection & NDT
The extended neck allows straightforward visual and non destructive examination (NDT) of the weld, supporting quality assurance and predictive maintenance.
6. Broad Material & Pressure Range
Available in carbon steel, stainless steel, and alloy steel grades, with pressure ratings from PN 2.5 to PN 400, covering nearly all industrial pressure needs.
Potential Material Selection for EN1092-1 WN Flanges
| Material Category | Common Grades | Temperature Range | Key Applications |
| Carbon Steel | S235JR, P265GH, A105 | -20°C to +400°C | Water systems, oil & gas, general industry |
| Stainless Steel | 1.4301 (304), 1.4401 (316) | -200°C to +400°C | Chemical processing, food & beverage, marine |
| Alloy Steel | A182 F11, F22, F91 | Up to +600°C | Power generation, high-temperature steam lines |
| Duplex Steel | 1.4462 (2205) | -50°C to +300°C | Offshore, chemical processing with chlorides |
Note: All materials must be supplied with appropriate certification (EN 10204 3.1/3.2) to verify compliance with EN1092-1 requirements.
Where EN1092-1 Weld Neck Flanges Are Essential
- Oil & Gas Industry: Pipeline connections, wellhead equipment, and processing facilities where high pressure and reliability are critical.
- Power Generation: Boiler connections, steam turbine inlets, and high-energy piping systems requiring high-temperature resistance.
- Chemical & Petrochemical: Processing equipment handling corrosive, toxic, or hazardous fluids where leak-tight integrity is paramount.
- Marine Applications: Shipboard piping systems exposed to corrosive seawater and dynamic loading conditions.
- Water Treatment Plants: High-pressure pump discharges, filter systems, and distribution networks requiring durable connections.
- Pharmaceutical & Food Processing: Sanitary systems where material purity and cleanability are essential.
Conclusion
EN1092-1 Weld Neck Flanges represent the gold standard for high-integrity pipe connections. Their welded construction, tapered-hub design, and full compliance with European dimensional and material standards make them the preferred choice for engineers who prioritize safety, longevity, and leak-free performance.
For projects requiring certified EN1092-1 Type 11 flanges—whether in carbon steel, stainless, or high-temperature alloys—partner with a supplier that provides full material traceability (EN 10204 3.1/3.2) and technical support.