Socket weld and threaded flange dimensions
The CSV uses semicolons as separators. The link carries the selected class and size.
| NPS | DN | D | k | n × lhole | b | g | Xhub | Ylength | Bsocket | Dsdepth | dSch 40 · 80 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | DN15 | 89 | 60.3 | 4 × 15.9 | 11.1 | 34.9 | 30.2 | 15.9 | 22.3 | 9.5 | 15.8 · 13.9 |
| 3/4" | DN20 | 98 | 69.8 | 4 × 15.9 | 12.7 | 42.9 | 38.1 | 15.9 | 27.7 | 11.1 | 20.9 · 18.9 |
| 1" | DN25 | 108 | 79.4 | 4 × 15.9 | 14.3 | 50.8 | 49.2 | 17.5 | 34.5 | 12.7 | 26.6 · 24.3 |
| 1 1/4" | DN32 | 117 | 88.9 | 4 × 15.9 | 15.9 | 63.5 | 59 | 20.6 | 43.2 | 14.3 | 35 · 32.5 |
| 1 1/2" | DN40 | 127 | 98.4 | 4 × 15.9 | 17.5 | 73.2 | 65 | 22.6 | 49.5 | 15.9 | 40.9 · 38.1 |
| 2" | DN50 | 152 | 120.6 | 4 × 19 | 19 | 92.1 | 77.8 | 25.4 | 62 | 17.5 | 52.5 · 49.2 |
| 2 1/2" | DN65 | 178 | 139.7 | 4 × 19.1 | 22.3 | 104.6 | 90 | 28.6 | 74.7 | 19.1 | 62.7 · 59 |
Notes
- This table has been compiled by Emsal from the relevant standards. For the full text of the standard, refer to ASME.
- Body dimensions (D, b, k, bolting, hub X and Y) are the same as the slip-on flange of the same class and size; dimensions are converted from the standard's inch values. Socket bore B and depth Ds are identical in two independent sources.
- The bore of a socket weld flange equals the pipe bore; values are given for Sch 40 and Sch 80 — state the schedule when ordering.
- Scope: these flanges are for small-bore lines; the table covers NPS ½"–2½", which both sources contain. The Class 900 2½" hub length of the threaded flange is left blank because the sources differ.
- Raised face (f): 1.6 mm for Class 150 and 300 and included in the thickness (b); 6.4 mm for Class 600 and 900 and not included in the thickness (ASME B16.5).
- Accuracy and currency are not guaranteed; use the current edition of the standard for design and purchasing decisions. How the library is compiled →
Dimension letters
| D | Flange outside diameter | g | Raised face diameter |
| k | Bolt circle diameter | f | Raised face height |
| b | Flange thickness | X | Hub diameter |
| Y | Length through hub | B | Socket bore |
| Ds | Socket depth | d | Bore (Sch 40 / 80) |
Joint type and P&ID symbol
The two types share the same body dimensions but are joined to the pipe differently.
Socket weld: the pipe is inserted into the flange socket, leaving an expansion gap of about 1.6 mm at the bottom, and a fillet weld is made at the hub.
Threaded: the flange is screwed onto the pipe; no welding is needed. Sealing is made on the thread (taper thread with sealing tape or compound).
Socket weld flanges are used on small-bore (usually NPS 2 and below) high-pressure lines; the gap at the bottom can trap abrasive or corrosive media. Threaded flanges are used where welding is not possible (flammable areas, galvanised pipe) and on small-bore low-pressure lines; thermal expansion and vibration can cause thread leaks.
Not to scale; proportions are indicative.
