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Flange Specification and Identification

Flange Specification and Identification

Flange Specification and Identification

A flange is specified by the following information:

  • Type and Facing. The flange is specified according to whether it is, for example, ‘‘weld-neck RTJ’’ or ‘‘socket-weld RF.’’ Ring joint facing and RTJ gasket dimensions for ASME B16.5.

  • Nominal Pipe Size (NPS). This is a dimensionless designation to define the nominal pipe size (NPS) of the connecting pipe, fitting, or nozzle. Examples include NPS 4 and NPS 6.

  • Flange Pressure Class. This designates the pressure temperature rating of the flange, which is required for all flanges. Examples include Classes 150, 300, 900, and 1500.

  • Standard. Basic flange dimensions for ASME B16.5. Examples include ASME B16.5, BS 1560, DIN or API 6A.

  • Material. A material specification for flanges must be specified and be compatible to the piping material specifications.

  • Pipe Schedule. This is only for WN, composite lap-joint and swivel-ring flanges where the flange bore must match that of the pipe, such as schedule 40, 80, 120, and 160.


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