EN 1759 Standards: Specification of Circular Flanges for Industrial Equipment
The EN 1759 series of standards regulates the requirements for class-designated circular flanges intended for piping systems, valves, and fittings. EV Group China’s technical solutions are based on these standards, ensuring full leak-tightness and reliability of connections under high-pressure and high-temperature conditions.
EN 1759-1: Steel Flanges (NPS ½ – 24)
Technical Specification of EN 1759-1
The EN 1759-1 standard establishes rigorous requirements for steel flanges with pressure classes from 150 to 2500 in the NPS size range from ½ to 24 inches. The document regulates geometry, tolerances, types of facing surfaces, bolting parameters, and test methods under operating loads.
Important note: when designing and ordering, it is necessary to consider the correlation between the nominal size (DN) and the nominal diameter (NPS) provided in the standard’s reference tables.
The standard does not apply to flanges machined from bar stock or to types 11–15 produced from plate material.
Typology of Steel Flanges
| Type | Description |
|---|---|
| 01 | Plate flange for welding |
| 05 | Blank flange |
| 11 | Weld-neck flange |
| 12 | Hubbed slip-on flange |
| 13 | Hubbed threaded flange |
| 14 | Hubbed socket-weld flange |
| 15 | Loose hubbed flange |
| 21 | Integral flange |
Sealing Surfaces (EN 1759-1)
- Type A: Flat face
- Type B: Raised face
- Type E: Spigot face
- Type F: Recess face
- Type CL/CS: Large/Small tongue
- Type DL/DS: Large/Small groove
- Type J: Ring-joint
EN 1759-3: Copper Alloy Flanges
This part of the standard defines the requirements for copper alloy flanges, including collars working in tandem with loose steel flanges. Pressure class range: 150–300, sizes: DN 10–900 (NPS ½–36).
Types of Flanges (Cu-Alloys)
| Type | Description |
|---|---|
| 01 | Flat flange for soldering/welding |
| 04/07 | Loose flanges with stub (types 34/37) |
| 05/05C | Blank flanges (integral or clad) |
| 11/12/14 | Weld-neck and hubbed versions |
EN 1759-4: Aluminum Alloy Flanges
The EN 1759-4 standard describes design requirements for aluminum alloy flanges (DN 15–600, classes 150–300). They are used in pipelines and pressure vessels. Main types: 05 (blank) and 11 (weld-neck).
EV Group China provides flange connections strictly complying with EN 1759 requirements, with the provision of all necessary technical documentation.