ASME B16.21 pdf download Nonmetallic Flat Gaskets for Pipe Flanges
This Standard covers types, sizes, materials, dimen- sions, tolerances, and markings for nonmetallic flat gas- kets. These gaskets are dimensionally suitable for use with flanges described in the referenced flange standards.
1.2 Relevant Units This Standard states values both in 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 stan- dard. Within the text, the U.S. customary units are shown in parentheses or in separate tables. The values stated in each system are not exact equivalents; therefore, it is required that each system of units be used in- dependently of the other. Except for diameter of bolts and flange bolt holes, combining values from the two systems constitutes nonconformance with the Standard.
1.3 Quality Systems Requirements relating to the product manufacturers’ quality system programs are described in Nonmanda- tory Appendix A.
1.4 References Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix II.
2 TYPES AND SIZES
2.1 Types Dimensions are provided for the following types of gaskets, which are suitable for use with the flange faces indicated:
NPS, followed by a dimensionless number, is the designation for normal pipe size, NPS, as described in ASME B36.10M; and is related to the reference nominal diameter, DN, used in international standards. The re- lationship is as follows:
GENERAL NOTE: For NPS 4, the related DN is DN ? 25 ? NPS 2.3 Pressure Class Designation Class, followed by a dimensionless number, is the designation for common flange pressure-temperature ratings as given by the referenced flange standards. 3 MATERIALS 3.1 Composition Gaskets shall be made of resilient or pliable materi- als. Metal or nonmetal composites may be incorporated as reinforcement or filler material.
3.2 Service Requirements Selection of a material suitable for a given service ap- plication is the responsibility of the user subject to the requirements of any applicable code or government reg- ulation. The material selected shall be compatible with the fluid and suitable for the pressure-temperature con- ditions of the service.
4 DIMENSIONS AND TOLERANCES
4.1 Dimensions Gasket dimensions shall be in accordance with Tables 1 through 9 (Tables I-1 through I-9 of Appendix I) for the flanges standards, sizes, and classes indicated. Se- lection of gasket thickness is the responsibility of the