Flanges

Types

Flanges connect pipe sections to valves, pumps, and equipment at joints that must be opened for maintenance. We supply all standard facing types:

• Weld neck (WN) - long tapered hub matched to pipe bore; preferred for high-pressure and cyclic service. The hub transfers stress gradually into the pipe wall.
• Slip-on (SO) - slides over the pipe OD and is fillet-welded inside and outside. Easier to align than weld neck; lower pressure rating.
• Lap joint - similar to slip-on but used with a stub end; the flange rotates freely to align bolt holes.
• Socket weld (SW) - pipe inserted into a socket and fillet-welded. Common on smaller bore pipe in high-pressure service.
• Screwed/threaded (SCRD) - threaded connection for low-pressure or no-weld situations.
• Blind - no bore; used to blank off the end of a pipe or nozzle. Carries the full line pressure on its full face.

Manufacture

Flanges are machined from near-net-shape forgings, cut plate, or forged bar. Forging gives a refined grain structure and superior mechanical properties compared with plate-cut material, which is why ASME requires forged flanges for Class 600 and above on most alloys.

Pressure classes and standards

We supply to ASME B16.5 (Class 150 to 2500, 1/2" to 24" NPS) and ASME B16.47 (Class 150 to 900, 26" to 60" NPS). Facing finishes to specification: raised face (RF), flat face (FF), ring type joint (RTJ).