ASME B16.21:2011 pdf free download Nonmetallic Flat Gaskets for Pipe Flanges
1 sCOPE
This Standard covers types, sizes, materials,dimen-sions, tolerances, and markings for nonmetallic flat gas-kets. These gaskets are dimensionally suitable for usewith flanges described in the referenced flangestandards.
2GENERAL
2.1 Relevant Units
This Standard states values both in SI (metric) andU.S.Customary units.As an exception, diameter of boltsand flange bolt holes are expressed in inch units only.These systems of units are to be regarded separately asstandard.Within the text, the U.s.Customary units areshown in parentheses or in separate tables. The valuesstated in each system are not exact equivalents; therefore,it is required that each system of units be used indepen-dently of the other. Except for diameter of bolts andflange bolt holes, combining values from the two sys-tems constitutes nonconformance with the Standard.2.2 Quality Systems
Requirements relating to the product manufacturers’quality systemprogramsare described inNonmandatory Appendix A.
2.3 References
Standards and specifications adopted by reference inthis Standard are shown in Mandatory Appendix II.
2.4Flanged Joints
A flanged joint is composed of separate and indepen-dent, although interrelated, components: the flanges,gasket,and bolting, which are assembled by anotherinfluence, the assembler. Proper controls must be exer-cised in the selection and application for all these ele-ments 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 flange facesindicated:
2.6 Size
NPS, followed by a dimensionless number, is the des- ignation for nominal pipe size, as described in ASME B36.10M and is related to the reference nominal diameter, DN, used in international standards. The rela- tionship is as follows:
GENERAL NOTE: For NPS ≥ 4, the related DN p 25 ? NPS
2.7 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 materials. 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 application is the responsibility of the user subject to the requirements of any applicable code or government regulation. The material selected shall be compatible with the fluid and suitable for the pressure-temperature conditions 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 1-9 of Mandatory Appendix I) for the flanges’ standards, sizes, and classes indicated. Selection of gasket thickness is the responsi- bility of the user, considering the properties of the gasket material as well as the intended service application.
4.2 Tolerances
(a) Outside diameter for
(1) NPS 12 and smaller:
+0.0, −1.5 mm (+0.0, −0.06 in.)
(2) NPS 14 and larger:
+0.0, −3.0 mm (+0.0, −0.12 in.)
(b) Inside diameter for
(1) NPS 12 and smaller, ±1.5 mm (±0.06 in.)
(2) NPS 14 and larger, ±3.0 mm (±0.12 in.)
(3) bolt circle diameter, ±1.5 mm (±0.06 in.)
ASME B16.21:2011 pdf free download
