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Weld Neck

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Weld Neck Flanges are attached by welding a pipe to the neck of the flange, transferring stress from the flange itself to the connected pipe. They are often used in high pressure applications. Two different Weld Neck Flanges
  • Stocked in sizes from 1/2" to 24".
  • Aluminum Weld Neck Flanges conform to ASM 6061 T6.
  • Carbon Steel Weld Neck Flanges conform to ASTM A105.
  • High Yield Weld Neck Flanges conform to ASTM A694 F52.
  • Stainless Steel Weld Neck Flanges conform to ASTM A182. Both 304L and 316L available.
  • Classes available range from 150# to 1500#.

More Information on Specifying the Right Weldneck Flange!

click here for bolting specifications Temperature/Pressure cross reference by Class
Three Weld Neck Flanges in Aluminum, Carbon Steel, Stainless Steel, and High Yield.

To start, select size. Follow the green box to refine selections as desired. Click “Lookup Product” any time after selecting size to display products matching criteria entered so far. Fields autofill when only one choice. Or use search box above.


Domestic = Made in the USA

Import = Made anywhere else


Originally the numbers for "Class" (150, 300, 600, etc.) was the pressure (psig) at the corresponding saturated steam temperature. Ratings today are different because of changes made in materials and flange design.  Link to chart of temperature/pressure by class is above.


Flanges are avaiable in aluminum, carbon steel and stainless steel in grades 304, 304L, 316 and 316L. The L designates "low carbon", making the fitting good for welding.


Bore refers to the pipe thickness on which this flange is to be used, typically values are STD (standard), S/10 (Schedule 10) and XH (extra heavy). These thickness vary with the diameter of the pipe according to published standards.


Flat Face Flanges have a gasket surface in the same plane as the face of the bolting circle.  For Raised Face Flanges, the gasket surface is raised slightly above the face of the bolting circle, concentrating more pressure on a smaller gasket area.