EN 1092-1 covers circular steel flanges from DN 10 to DN 4000, rated by nominal pressure (PN), most often PN 6, PN 10, PN 16, PN 25 and PN 40. A PN 16 flange is not a drop-in substitute for a Class 150 ASME flange: the drilling can match on some sizes, but the two systems are not dimensionally interchangeable, so the standard must be stated on the enquiry.
What EN 1092-1 is, and what it is not
EN 1092-1 is the European standard for circular steel flanges designated by a PN rating. It replaced the older DIN designations (DIN 2501, DIN 2527, DIN 2633 and others) that still appear on many drawings. Part 1 covers steel flanges only; flanges in cast iron, copper alloy and other materials sit in other parts of the EN 1092 series.
PN ratings and typical applications
| PN rating | Common applications | Carbon steel grades | Stainless grades |
|---|---|---|---|
| PN 6 / PN 10 | Water, air and low-pressure utility | P235GH, P250GH | 1.4301 |
| PN 16 | General process, water and building services | P250GH, P265GH | 1.4404 |
| PN 25 / PN 40 | Higher-pressure process lines | P250GH, P265GH | 1.4404, 1.4571 |
The PN number is a nominal pressure class, not a working pressure in bar at every temperature. The allowable pressure at the working temperature is read from the pressure–temperature rating for the material in the standard.
Flange types by EN number
| Type | Name | How it joins the pipe |
|---|---|---|
| 01 | Plate flange for welding | Flat disc slipped over the pipe and fillet welded; low-pressure utility |
| 02 | Loose plate flange with weld-on collar | Backing flange behind a weld-on collar; eases bolt-hole alignment |
| 05 | Blank (blind) flange | Closes a line or vessel opening; removable |
| 11 | Weld neck flange | Butt welded with a tapered hub; high pressure and fatigue service |
| 12 | Hubbed slip-on flange | Slip-on with a hub; fillet welded |
| 13 | Hubbed threaded flange | Screwed onto the pipe; used where welding is not permitted |
The types most often supplied here are 01, 05 and 11. Other types and special designs are quoted against the drawing.
Facing forms
| Form | Facing | Where it is used |
|---|---|---|
| A | Flat face | Mating to cast iron or bronze equipment |
| B1 / B2 | Raised face | The default for most process and utility lines |
Other facing forms (tongue and groove, spigot and recess) are defined in the standard for special sealing. The facing, the gasket and the flange it bolts to must all match.
Materials
| Material | EN designation | Material number | Typical use |
|---|---|---|---|
| Carbon steel | P235GH | 1.0345 | Low pressure, utility |
| Carbon steel | P250GH | 1.0460 | General process |
| Carbon steel | P265GH | 1.0425 | Higher-pressure process |
| Stainless steel | X5CrNi18-10 (1.4301) | 1.4301 | General corrosion service |
| Stainless steel | X2CrNiMo17-12-2 (1.4404) | 1.4404 | Chloride and chemical service |
| Stainless steel | X6CrNiMoTi17-12-2 (1.4571) | 1.4571 | Higher temperature, welded |
Material numbers and designations follow EN 10027-1 / EN 10027-2. State the material and its inspection certificate requirement on the enquiry.
What to state on an EN 1092-1 enquiry
State the standard (EN 1092-1), DN size, PN rating, flange type number, facing form and material. Quantity and destination port follow. Flanges are supplied with EN 10204 3.1 certificates, with 3.2 on request.
Boundary: what EN 1092-1 does not do
EN 1092-1 does not make a flange interchangeable with an ASME B16.5 flange: the pressure classes, bolt circles and facings are separate systems, and a PN rating must not be read as a Class rating. The standard also does not cover non-circular or non-steel flanges.
Frequently asked questions
Is EN 1092-1 the same as the old DIN flange standard?
EN 1092-1 replaced the older DIN designations, so a drawing that still names DIN 2501, DIN 2527 or DIN 2633 is usually calling up a flange now defined by EN 1092-1. Confirm the equivalent type number before ordering.
Is a PN 16 flange the same as a Class 150 flange?
No. The bolt circles and drilling can match on common sizes, but the PN and Class systems are not dimensionally interchangeable. State the standard so the flange is matched to the correct table.
What is the difference between a Type 01 and a Type 11 flange?
Type 01 is a plate flange for welding, slipped over the pipe and fillet welded, used for low-pressure utility. Type 11 is a weld neck flange, butt welded with a tapered hub, for high pressure, high temperature and fatigue service.
What does Form B1 mean?
Form B1 is a raised face; Form A is a flat face. The facing must match the gasket and the flange it bolts to, so name the form on the enquiry.
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Related pages
ASME flange types and ordering: pipe flanges. ASME dimensions: ASME B16.5 flange dimensions and ASME B16.47. Material grades: ASTM A105 and ASTM A182 F316.
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