ASME B16.20:2007 pdf download Metallic Gaskets for Pipe Flanges Ring-Joint, Spiral-Wound, and lacketed
1 SCOPE
1.1 General
This Standard covers materials, dimensions, tolerances, and markings for metal ring-joint gaskets, spiralwound metal gaskets, and metal-jacketed gaskets. Thescgaskets are dimensionally suitable for use with flangesdescribed in reference flange standards ASME B16.5ASME B16.47,APISpecification 6A,and ISO 10423.ThisStandard covers spiral-wound metal gaskets and metal-jacketed gaskets for use with raised-face and flat-faceflanges.
1.2 Quality Systems
Requirements relating to the product manufacturersquality system programs are described in Nonmanda-tory Appendix A.
1.3 References
Standards and specifications adopted by reference inthis Standard are shown in Mandatory Appendix Il,which is part of this Standard.
1.4 Relevant Units
This Standard states alues in both metric and U.SCustomary units. These systems of units are to beregarded separately as standard.Within the text, the US Customary units are shownin parentheses or in separate tables. The values statedin each system are not exact equivalents; therefore, it isrequired that each system of units be used indepen-dently of the other. Combining values from the twosystems constitutes nonconformance with the Standard.
2 RING-JOINT GASKETS
2.1 Types
Ring-joint gaskets shall be either octagonal or oval incross section.
2.2 Size
Ring-joint gaskets shall be identified by an R, RX, orBX number that relates to flange size (NPS) pressureclass, and the appropriate flange standards (ASMEB16.5,ASME B16.47,APISpecification 6A,or ISO 10423)
2.3 Materials
2.3.1 General. Ring-joint gasket materials, some ofwhich are listed in Table 1, shall be selected by the userbased on suitability for the service conditions.It is recommended that ring-joint gaskets be of a lesserhardness than that of the mating flanges.
2.3.2 Hardness. Ring-joint gaskets of materialslisted in Table 1 shall have a hardness equal to or lessthan that shown in Table 1.
2.4 Marking
The outer surface of each gasket shall carry the manu-facturer’s name or identification trademark and gasketnumber prefixed by the letters R RX, or BX, followedby the gasket material identification. Materials shall beidentified as shown in Table 2. The gasket shall also bemarked with an ASME B16.20 designation. The markingshall be applied so as not to harmfully distort the gasketor affect the integrity of the seal.
2.5 Dimensions and Tolerances
Dimensions and tolerances for ring-joint gaskets shallbe as shown in Tables 3 through 8 (Tables I-1, I-2, andI-3 of Mandatory Appendix I).
2.6 Surface Finish
Types R and RX gaskets shall have a surface finishnot rougher than 1.6 um (63 pin.) roughness. Type BX