ASME B16.21-2021 pdf free download.Nonmetallic Flat Gaskets for Pipe Flanges
This Standard covers types, sizes, materials, dimen- sions, tolerances, and markings for nonmetallic flat gaskets. These gaskets are dimensionally suitable for use with flanges described in the referenced flange standards. 2 GENERAL
2.1 Relevant Units This Standard states values both in SI (metric) and U.S. Customary units. As an exception, diameter of bolts and flange bolt holes are expressed in inch units only. These systemsofunitsaretoberegardedseparatelyasstandard. 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 described 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 indepen- dent, although interrelated, components: the flanges, gasket, and bolting, which are assembled byanotherinflu- ence, the assembler. Proper controls must be exercised in the selection and application for all these elements to attain ajointthathas acceptable leaktightness. Additional guidelines for flange assembly can be found in ASME PCC-1 (see Nonmandatory Appendix B).
2.5 Types Dimensions are provided for the following types of gaskets, which are suitable for use with the flange faces indicated:
2.6 Size NPS, followed by a dimensionless number, is the des- ignation for nominal pipe size, as described in ASME B36.10M andis relatedto thereference nominaldiameter, DN, used in international standards. The relationship is as follows:
GENERAL NOTE: For NPS ≥ 4, the related DN = 25 × NPS.
2.7 Pressure Class Designation
Class, followed by a dimensionless number, is the des- ignation 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 ofa material suitable fora given service appli- cation is the responsibility of the user subject to the re- quirements 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
5 MARKINGS 5.1 Material Marking Unless otherwise specified by the purchaser, gasket materialshallbemarkedwiththematerialmanufacturer’s name or trademark and material designation.
5.2 Gasket Marking Gaskets shall be packagedwithNPS, class, gasketmanufacturer’s name, material designation, thickness, and ASME B16.21 marked or tagged on the package or gasket. At the option of the manufacturer, the DN desig- nation may be included.ASME B16.21 pdf download.ASME B16.21-2021 pdf free download
