ASME B16.21:2021 pdf free 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 for
use with flanges described in the referenced flange stan-dards.
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.Thesesystems of units are to be regarded separately as standard.
In this Standard, the U.s. Customary units are shown inparentheses.The values stated in each system are notexact 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 described in NonmandatoryAppendix A.
2.3 References
Standards and specifications adopted by reference inthis Standard are shown in Mandatory Appendix I.
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.Additionalguidelines for flange assembly can be found in 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:
2.7 Pressure Class Designation
Class, followed by a dimensionless number, is the des-ignation for common flange pressure-temperatureratings 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 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 re-quirements of any applicable code or governmentregulation. The material selected shall be compatible with the fluid and suitable for the pressure-temperatureconditions of the service.
4 DIMENSIONS AND TOLERANCES
4.1 Dimensions
Gasket dimensions shall be in accordance withTables 4.1-1 through 4.1-9 for the flanges’ standards,sizes, and classes indicated.Selection of gasket thicknessis the responsibility of the user, considering the propertiesofthe gasket material as well as the intended service appli-cation.
5 MARKINGS
5.1 Material Marking
Unless otherwise specified by the purchaser, gasketmaterialshall 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 included.