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 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. 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 ofunits 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 s ys tem p ro grams are des crib ed in Nonmandatory Appendix A. 2.3 References Standards and specifications adopted by reference in this 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 assembledbyanotherinflu- ence, the assembler. Proper controls must be exercised in the selection and application for all these elements to attain a joint that has acceptable leak tightness. 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 indicatsd:2.6 Size NPS, followed by a dimensionless number, is the desig- nation for nominal pipe size, as described in ASME B36.10M andis relatedto thereference nominaldiameter, DN, used in international standards. The relationship is as follows:2.7 Pressure Class Designation Class, followed byadimensionless number, is the desig- nation 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 requirements ofanyapplicable code or governmentregu- lation. The material selected shall be compatible with the fluid and suitable for the pressure–temperature condi- tions of the service.
4 DIMENSIONS AND TOLERANCES
4.1 Dimensions Gasketdimensions shall be in accordance with Tables 1 through 9 (Tables I-1 through I-9 ofMandatory Appendix I) for the flanges’ standards, sizes, and classes indicated. Selection of gasket thickness is the responsibility of the user, considering the properties ofthe gasket material as well as the intended service application.
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, gasketmanu- facturer’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.