Industrial Flanges — ASME B16.5, EN 1092-1, DIN and JIS
Five flange families cover almost every piping connection: weld neck for high-pressure and cyclic service, slip-on for economical low-pressure lines, blind for isolation, socket weld for small-bore high-pressure tubing, and custom machining for everything the standards do not cover.
We machine to ASME B16.5 (1/2″–24″) and B16.47 (26″–60″), EN 1092-1 (DN10–DN1200), DIN 2632/2633 and JIS B2220, in carbon, stainless, alloy and duplex steel. Pressure classes run from 150 to 2500 with RF, FF and RTJ faces. Material, dimension and test certificates are issued against the same heat number.
Which flange type fits your line?
| Type | Best for | Class | Connection | Relative cost |
|---|---|---|---|---|
| Weld neck | High pressure, cyclic, high temperature | 150–2500 | Butt weld | Highest |
| Slip-on | Low pressure, easy alignment | 150–2500 | Fillet both sides | Low |
| Blind | Isolation, test points, line ends | 150–2500 | Bolted only | Medium |
| Socket weld | Small bore, high pressure | 150–2500 | Fillet in socket | Low–medium |
| Threaded | Small bore, no welding | 150–2500 | Threaded | Low |
| Lap joint | Frequent dismantling, stub ends | 150–2500 | Lap + stub end | Medium |
Popular sizes
Not listed? Send the size and class — we quote Class 600–2500 and sizes up to 60″ as well.
Faces, finishes and documentation
Raised face (RF) is the default for ASME and EN flanges and takes a spiral-wound or sheet gasket. Flat face (FF) is used with full-face gaskets, often against cast iron or FRP equipment. Ring-type joint (RTJ) flanges carry a machined groove and a metal ring for high-pressure and high-temperature service, and are not interchangeable with RF flanges. Face finish is normally 125–250 AARH; smoother or rougher finishes are available on request.
Every flange is supplied with a heat-number stamping, EN 10204 3.1 certificate and dimensional inspection record. PMI, UT and third-party inspection can be added at the quotation stage.
Sizes and classes, briefly
ASME flanges are sized by nominal pipe size (NPS) and rated by class, not by a single pressure number. The class sets the wall thickness, bolt count and bolt size; the actual allowable pressure depends on the material group and the design temperature, so a Class 300 flange in A105 is not rated at a fixed 300 psi.
EN and DIN flanges use DN for size and PN for pressure. A DN50 PN16 flange and a 2″ Class 150 flange are close in duty but have different outside diameters and bolt circles — they will not bolt together. Always order to one standard family, including the gasket and bolts.
What a complete order includes
- Standard and edition, size, class and face type
- Material grade and certificate level (3.1 or 3.2)
- Quantity per size and marking requirements
- Inspection: dimensional report, PMI, UT/MT if required
- Packing: plywood case or pallet, face protection, ISPM 15
Standard sizes in A105 ship in 7–15 days; alloy grades, RTJ faces and non-standard bolt patterns typically take 20–30 days. If the order has to meet a shutdown window, send the required-on-site date with the inquiry — we will confirm what can be committed rather than quoting an optimistic lead time.