ASME B16.21-2021 pdf – Nonmetallic Flat Gaskets for Pipe Flanges.
ASME B16.21 covers types, sizes, materials, dimensions. tolerances, and markings for nonmetallic flat gaskets. These gaskets are dimensionally suitable for use with flanges described In the referenced flange stanclards.
2.1 ReLevant Units
This Standard states values both in SI (metric) and U.S. Customary units. As an exception, diameter of baits and flange bolt holes are expressed in inch units only. These syslems ulunitsare to be regarded separately as standard. In this Standard, the u.S. Customary units are shown in parentheses. The values stated in each system are 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.
2.2 QuaLity Systems
Requirements relating to the product manufacturers’ quality system programs are descnbed in Nonmandatory Appendix A.
2.3 References
Standards and specifications adopted by reference In this Standard are shown in Mandatory Appendix I.
2.4 Flanged Joints
A flanged joint is composed of separate and indc’pc’ndent, although Interrelated, components: the flanges. gasket, and bolting, which are assembled by another influence, the assembler. Proper controls must be exercised in the selection and application for all these elements to attain a joint that has acceptable leak tightness. Additional guidelines for flange assembly can be found In ASME PCC-1 (see Nanmandatory Appendix H).
2.5 Types
Dimensions are provided for the following types of gaskets, which are suitable for use with the flange faces indicated:
5.1 Material Marking
Unless otherwise specified by the purchaser, gasketmaterial shall be marked with the material manufacturer’sname or trademark and material designation.
5.2 Gasket Marking
Gaskets shall be packaged with NPS, class, gasket manu-facturer’s name, material designation, thickness,andASME B16.21 marked or tagged on the package orgasket.At the option of the manufacturer, the DN desig-nation may be fncluded.