Welding neck flange is a type of pipe fittings which has “round neck” in the center. The “round neck” is already bevelled which is directly for welding with the pipe ends. The outside diameter of the “round neck” is the same as the connected pipe outside diameter. In general, the outside diameter for the “round neck” hole is ranges from 50mm to 2130mm. Around the “round neck” there are 4 to 48 bore hole which is used with bolts to connect two flanges together. The outside diameter for the bore hold ranges from 11mm to 30mm. The outside diameter for welding neck flange ranges from 75mm to 2190mm, and the thickness is from 12mm to 58mm. There are five types of sealing face for welding neck flange which are RF, MFM, TG, FF, RJ. 
 
Welding neck flange has good sealing and distortion properties with a relatively cheap price. It is widely applied for pressure or temperature fluctuation pipeline under the nominal pressure less than PN 2.5 MPa, and also used for transporting expansive, flammable and explosive media with a nominal pressure around PN 16 MPa.