scope:

General

This Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60 and in ratings Classes 75, 150, 300, 400, 600, and 900. Flanges may be cast, forged, or plate (for blind flanges only) materials, as listed in Table 1A.

Requirements and recommendations regarding bolting and gaskets are also included.

Flange Series

This Standard provides two series of flange dimensions. Series A specifies flange dimensions for general use flanges. Series B specifies flange dimensions for compact flanges which, in general, have smaller bolt circle diameters than Series A flanges. These two series of flanges are not interchangeable. The user should recognize that some flanged valves, equipment bolted between flanges, and flanged equipment may only be compatible with bolt circle diameter of one series of flanges.

References

Referenced Standards. Standards and specifications adopted by reference in this Standard are shown in Annex E, which is part of this Standard. It is not considered practical to identify the specific edition of each standard and specification in the individual references. Instead, the specific edition reference is identified in Annex E. A flange manufactured in accordance with earlier editions of the referenced standards, and in all other respects conforming to this Standard, will be considered to be in conformance with this Standard.

Codes and Regulations. A flange used under the jurisdiction of the ASME Boiler and Pressure Vessel Code (ASME BPV Code), the ASME Code for Pressure Piping, or a governmental regulation is subject to any limitation of that code or regulation. This includes any maximum temperature limitation, rule governing the use of a material at low temperature, or provisions for operation at a pressure exceeding the pressure-temperature ratings in this Standard.

Applicable Ratings

The pressure-temperature ratings in this Standard are applicable upon its publication to all flanges within its scope which otherwise meet its requirements. For unused flanges maintained in inventory, the manufacturer of the flange may certify conformance to this Edition, provided he can demonstrate that all requirements of this Edition have been met. Where such components were installed in accordance with the pressure-temperature ratings of an earlier edition of this Standard, those ratings are applicable, except as maybe governed by the applicable code or regulation (see para. 1.3.2).

User Accountability

This Standard cites duties and responsibilities that are to be assumed by the user in the areas of application, installation, hydrostatic testing, operation, and material selection.

Quality Systems

Nonmandatory requirements relating to the product manufacturer's Quality System Program are described in Annex D.