ASME B16.21:2016 pdf download

ASME B16.21:2016 pdf download Nonmetallic Flat Gaskets for Pipe Flanges
1 scoPE
This Standard covers types, sizes, materials, dimen-sions,tolerances, and markings for nonmetallic flatgaskets.These gaskets are dimensionally suitable foruse with flanges described in the referenced flangestandards.
2 GENERAL
2.1 Relevant Units
This Standard states values both in Sl [metric] and u.s.Customary units.As an exception, diameter of bolts andflange bolt holes are expressed in inch units only. These
systems of units are to be regarded separately as standardWithin the text, the US. Customary units are shown in
parentheses or in separate tables. The values stated ineach system are not exact equivalents; therefore, it is
required that each system of units be used independentlyof the other. Except for diameter of bolts and flange boltholes, combining values from the two systems constitutesnonconformance with the Standard.
2.2 Quality Systems
Requirements relating to the product manufacturers’quality system programs are described in
Nonmandatory Appendix A.
2.3 References
Standards and specifications adopted by reference inthis Standard are shown in Mandatory Appendix II.2.4 Flanged Joints
A flanged joint is composed of separate and indepen-dent, although interrelated, components: the flanges,
gasket, and bolting. which are assembled by another influ-ence, the assembler. Proper controls must be exercised inthe selection and application for all these elements to
attain a joint that has acceptable leak tightness.
Additional guidelines for flange assembly can be foundin ASME PCC-1 (see Nonmandatory Appendix B).
2.5 Types
Dimensions are provided for the following types ofgaskets, which are suitable for use with the flangefaces indicated:
2.6 Size NPS, followed by a dimensionless number, is the desig- nation for nominal pipe size, as described in ASME B36.10M and is related to the reference nominal diameter, DN, used in international standards. The relationship is as follows:
GENERALNOTE:For NPS ≥ 4, the related DN = 25 × NPS.
2.7 Pressure Class Designation
Class, followed by a dimensionless number, is the desig-nation for common flange pressure-temperature ratingsas given by the referenced flange standards.
3 MATERIALS
3.1 Composition
Gaskets shall be made of resilient or pliable materials.Metal or nonmetal composites may be incorporated asreinforcement or filler material.
3.2 Service Requirements
Selection of a material suitable for a given service appli-cation is the responsibility of the user subject to the
requirements of any applicable code or government regu-lation.The material selected shall be compatible with thefluid and suitable for the pressure-temperature condi-tions of the service.
4 DIMENSIONS AND TOLERANCES4.1 Dimensions
Gasket dimensions shall be in accordance with Tables 1through (Tables l-1 through l-9 of Mandatory Appendixl) for the flanges’standards, sizes, and classes indicated.Selection of gasket thickness is the responsibility of the