Raised Face Flanges

The Raised Face (RF) type is the most applied flange face, and is easily to identify. It is referred to as a raised face because the gasket surfaces are raised above the bolting circle face.

Specifications covering the manufacture and dimensions of flanges:

ASTM SPECIFICATIONS

ASTM specifications regulate approved raw materials for which flanges can be made and specifications .

For stainless flanges are: ASTM A.182 - Forged or Rolled Alloy Steel Pipe Flanges & Fittings for high temperature service.

ANSI AND MSS SPECIFICATIONS

The standards govern the dimensions and tolerances to which fitting are manufactured: ANSI B. 16.5                       - Steel Pipe Flanges and Flanged Fittings (½ inch to 24 inch nominal diameter) MSS SP.6                             - Flange Facings MSS SP.25                           - Marking of flanges    MSS SP.39                           - Bolts and Nuts for Flanges MSS SP.44                           - Large Diameter Pipeline Flanges. (Over 24 inch dia) API-605                                - Large Diameter Flanges for petroleum Usage. (Over 24 inch dia)

 The ASME Code is not a standard as such but section VIII provides the procedure for calculating dimensions For all pressurised vessels flanges. The following are not flange specifications but they influence the manufacture of forged steel flange ANSI B. 31.10                     - Code for Pressure Piping ANSI B. 31.3                        - Petroleum Refinery Piping ANSI B. 31.4                        - Oil Transportation Piping ANSI B. 31.5                        - Refrigeration Piping Systems ANSI B. 31.7                        - Nuclear Power Piping ANSI B. 31.8                        - Gas Transmission and Distribution Piping systems ANSI B. 36.10                     - Standard for Wrought Steel pipe ANSI B. 36.19                     - Standard for Stainless Steel Pipe ANSI B. 16.10                     - Valve Dimensions Face & End ANSI B. 16.11                     - Forged Fittings Socket Weld & Threaded