Large Diameter Steel Flanges NPS 26 Through NPS 60 Metric/Inch Standard
|Publication Date:||1 January 2006|
This Standard covers pressure-temperature
This Standard is limited to
(a) flanges made from cast or forged materials
(b) blind flanges made from cast, forged, or plate materials (see Tables 1 and 2)
Also, included in this Standard are requirements and recommendations regarding flange bolting, flange gaskets, and flange joints.
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 that, in most cases, have smaller bolt circle diameters than Series A flanges. These two series of flanges are, in general, not interchangeable. The user should recognize that some flanged valves, equipment bolted between flanges, and flanged equipment may be compatible with only one series of these flanges.
Time of Purchase, Manufacture, or Installation
This Standard cites responsibilities that are to be assumed by the flange user in the areas of, for example
(c) system pressure testing
(e) material selection
Requirements relating to the product manufacturer's Quality System Program are described in Mandatory Appendix II.
This Standard states values in both SI (metric) and U.S. Customary units. As an exception, diameter of bolts and flange bolt holes are expressed in inch units only. These systems of units are to be regarded separately as standard. Within the text, the U.S. Customary units are shown in parentheses or in separate tables. The values stated in each systemare not exact equivalents; therefore, it is required that each system of units be used independently of the other. Except for diameter of bolts and flange bolt holes, combining values from the two systems constitutes nonconformance with the Standard.
Criteria for selection of materials suitable for particular fluid service are not within the scope of this Standard.
For the purpose of determining conformance with this Standard, the convention for fixing significant digits where limits, maximum and minimum values are specified, shall be rounded as defined in ASTM Practice E 29. This requires that an observed or calculated value shall be rounded off to the nearest unit in the last right hand digit used for expressing the limit. Decimal values and tolerances do not imply a particular method of measurement.
Pressure Rating Designation.
Class, followed by a dimensionless number, is the designation
NPS, followed by a dimensionless number, is the designation for nominal flange size. NPS is related to the reference nominal diameter, DN, used in international and other standards. For the sizes covered in this Standard, the relationship is: DN = 25 x NPS.