ASME B16.20-2007 pdf download.Metallic Gaskets for Pipe Flanges Ring-Joint, Spiral-Wound, and Jacketed .
1 SCOPE 1.1 General This Standard covers materials, dimensions, toler- ances, and markings for metal ring-joint gaskets, spiral- wound metal gaskets, and metaljacketed gaskets. These gaskets are dimensionally suitable for use with flanges described in reference flange standards ASME B16.5, ASME B16.47, API Specification 6A, and ISO 10423. This Standard covers spiral-wound metal gaskets and metal- jacketed gaskets for use with raised-face and flat-face flanges. 1.2 Quality Systems Requirements relating to the product manufacturers’ quality system programs are described in Nonmanda- tory Appendix A. 1.3 References Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix II, which is part of this Standard. 1.4 Relevant Units This Standard states values in both metric and U.S. Customary units. These systems of units are to be regarded separately as standard. 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 indepen- dently of the other. Combining values from the two systems constitutes nonconformance with the Standard. 2 RING-JOINT GASKETS 2.1 Types Ring- joint gaskets shall be either octagonal or oval in cross section.
2.3 Materials 2.3.1 General Ring joint gasket materials, some of which are listed in Table 1, shall be selected by the user based on suitability for the service conditions. It is recommended that ring-joint gaskets be of a lesser hardness than that of the mating flanges. 2.3.2 Hardness. Ring joint gaskets of materials listed in Table 1 shall have a hardness equal to or less than 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 gasket number prefixed by the letters R, RX, or BX, followed by the gasket material identification. Materials shall be identified as shown in Table 2. The gasket shall also be marked with an ASME B16.20 designation. The marking shall be applied so as not to harmfully distort the gasket or affect the integrity of the seal. 2.5 Dimensions and Tolerances Dimensions and tolerances for ring joint gaskets shall be as shown in Tables 3 through 8 (Tables 1-1, 1-2, and 1-3 of Mandatory Appendix I).
2.7 ldentification Number Dimensional reference identification numbers are assigned to ring-joint gaskets and are shown in Tables 3 through 8 (Tables I-1, I-2, and I-3 of Mandatory Appen- dix D). 3 SPIRAL-WOUND GASKETS 3.1 Size and Class Spiral-wound gaskets, including centering ring and inner ring (paras.3.2.4 and 3.2.5), are identified by flange size (NPS), pressure class, and the appropriate flange standard (ASME B16.5 or ASME B16.47). 3.2 Dimensions and Tolerances 3.2.1 General. Dimensions and tolerances for spi- ral-wound gaskets, centering rings, and inner rings shall be in accordance with Tables 9 through 14 (Tables I-4 through I-9 of Mandatory Appendix I) and as specified in this section. 3.2.2 Construction. Spiral-wound gaskets shall be constructed as alternate plies (circular layers counted as revolutions) of preformed metal windings and pliant fillers that are spirally wound. For the finished gasket, the filler shall be essentially flush with, but not below, the metal winding on both contact faces of the gasket. The metal strip in the winding shall be 0.15 mm (0.006 in.) to 0.23 mm (0.009 in.) thick. The fller material thickness shall be determined by the manufacturer.