A weld neck flange, also called a tapered hub flange or high-hub flange, is a kind of flange that can relocate stress to the pipes, ensuring a decrease in high-stress concentration at the bottom of the flange. There are two welding neck flanges designs – the first type is used with wipes while the second, longer type cannot be used with pipes but with a process plant. The weld neck flange comprises of a round fitting that extends beyond the rim of the circumference. These flanges, typically manufactured from forging, are actually welded to pipes.
The rim has numerous holes drilled into it that enables the flanged to be attached to a bolted flange. This design is far better because of the structural valve.
Common outer diameters: 1/2”, 2”, 3”, 4”, 6”, 8”, 10”, 12” to 24”.
Special made outer diameters: up to 60”.
Class range: Class 150, 300, 400, 600, 900, 1500, 2500(# or LB). PN 2.5 to PN 250.
Flange face type: RF (Raised Face), RTJ (Ring Type Joint)
Standards for WN flanges:
ASTM A105 for carbon steel welding neck flanges.
ASTM A182 for alloy and stainless welding neck flange. (Alloy for F11, F22, stainless for F304/F304L, F316/F316L)
DIN 2630 PN 1 and PN 2.5, 2631 PN 6, 2632 PN 10, 2634 PN 16, 2634 PN 25, 2635 PN 40
Prior to ordering the weld neck flange, the companies shall need to confirm the material standard, outer diameter, pressure class, face type and thickness schedule.
A standard description for welding neck flange is:” Flange, 8” Weld Neck, Class 150, RF, Schedule 40, ASTM A105 ASME B 16.5.”