Weld neck flange is widely used in pipeline network to connect various pipe assemblies, such as valves, special goods and connecting equipment. They are usually made from forging, the material is commonly ASTM A105.
Weld neck flange is welded to pipe.
1. Weld neck flanges are used mainly in these locations as all welds in critical services require radiography.
2. The thickness of welding neck flange should be specified, usually the same thickness as the same size. 3. Welding neck flange is more expensive, and used for high temperature, flammable, toxic and other services.
Facings of weld neck flange:
1. Flat Face (FF)
2. Raised Face (RF)
3. Male-Female (FM)
4. Tongue-Groove (TG)
5. Rig Type Joint (RTG)
Please see the following sample pictures about flange facings.
1. Flat face flange:
Flat face flange is mainly used to connect cast iron equipment, valves and special components. The gasket surface of the plane flange is on the same plane as the bolt connection.
2. Raised Face (RF)
The raised face pipe flange is the most commonly used flange.The raised face thickness of 150 # and 300 #is included in the specified flange thickness. For higher rating flanges, they are not included in the flange thickness. Raised face is very commonly for weld neck flange.
Carbon steel ANSI B16.5 weld neck flange face finishes.
1. The available face surface treatment is finished in stock, smooth/serrated and extra smooth finish.
2. The end flange is used with non-metal gaskets.
3. The allowable roughness of the stock surface flange is 250-500 or 500 to 1000 micro - inch AARH.
4. Smooth/serrated face flanges are used in conjunction with metal or spiral wound gaskets.
5. Smooth/serrated face flanges allow for a roughness of 125-250 microinch AARH.
6. Metal RTJ and T/G flanges are used for additional smoothing flanges.
7. The maximum allowable roughness of the super-smooth flange is 63 microinch AARH.
8. Flange face sawtooth type concentric and helix.
9. Spiral serrated general use type.
10. Concentric serrations are used for conveying fluid highly flammable or toxic or low molecular weight gases.