ASME B16.21-2016 pdf download

ASME B16.21-2016 pdf download.Nonmetallic Flat Gaskets for Pipe Flanges.
This Standard covers types, sizes, materials, dimensions, 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 systems of units are to be regarded separately as standar 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 of units be used independently of the other. Except for diameter of bolts and flange bolt holes, combining values from the two systems constitute 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 II.
2.4 Flanged Joints
A flanged joint is composed of separate and independent, although interrelated, components: the flanges. gasket, and bolting, which are assembled by another influ 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 indicated:
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 1-1 through 1-9 of Mandatory Appendix I) for the flanges’ standards, sizes, and classes indicated. Selection of gasket thickness is the responsibility of the user, considering the properties of the gasket material aswell as the intended service application.
4.2 Tolerances
(a) Outside diameter for(1) NPS 12 and smaller:
+0.0 mm,1.5 mm (+0.0 in.,0.06 in.)
(2) NPS 14 and larger:
+0.0 mm,3.0 mm (+0.0 in.，0.12 in.)
(b) Inside diameter for
(1 ) NPS 12 and smaller: 1.5 mm (士0.06 in.)(2) NPS 14 and larger: 13.0 mm (主0.12 in.)(3) bolt circle diameter: ±1.5 mm (±0.06 in.)
(4) center to center of adjacent bolt holes: 土1.0 mm(±0.03 in.)