Tuesday, January 29, 2008

ASME/ANSI Pipe Flanges


Pipe flanges that are made to standards called out by ASME/ANSI B16.5 or ASME/ANSI B16.47 are typically made from forged materials and have machined surfaces. They are typically in "Pressure Classes" such as 150#, 300#, 600#, 900# 1500#; however, ASME B16.47 still recognizes the 75# or "Class 75" flange for certain low pressure and low temperature applications. These "Pressure Classes" have both pressure and temperature ratings for specific materials.

The flange faces are made to standardized dimensions and are typically "flat face" "raised face" "tongue and grove" or "ring joint" styles, although other obscure styles may be permitted.

Flange designs are available as "welding neck" "slip-on" "lap joint" "socket weld" "threaded" and also "blind flange".


The gasket type and bolt type are generally specified by the standard(s); however, sometimes the standards refer to the ASME Boiler and Pressure Vessel Code (B&PVC) for details ( see ASME Code Section VIII Division 1 - Appendix 2 ). These flanges are recognized by ASME Pipe Codes such as ASME B31.1 Power Piping, and ASME B31.3 Process Piping.

Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications) , SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components) or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service).

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