ASME B16.20:2012 pdf free download

ASME B16.20:2012 pdf free download.Metallic Gaskets for Pipe Flanges.
5.2 Dimensions and Tolerances
5.2.1 General. Dimensions and tolerances for grooved metal gaskets with covering layers and centering rings shall be in accordance with Fig. 3 and Tables 26 through 2 (Tables 1-15 through 1-17 of Mandatory Appendix I) and as specified in this section.
5.2.2 Construction. Grooved metal gaskets with covering layers shall be constructed as a concentrically grooved metal core (sealing element) with a centering ring. The grooved metal portion of the finished gasket shall be laced with a covering layer on both sealing surfaces that is0.4i-mm (0.018-in.) to0.56-mm (0,022-in.) thick. The thickness of the metal core of the gasket shall be 2.97mm (0.117 in.) to 3.33 mm (0.131 in.). The thickness on any single gasket shall be uniform within a maximum tolerance range of 0.13 mm (0.005 itt).
5.2.3 Welding. Welding is permitted only in NPS 14 and larger gaskets, Welding shall be subcct to the following;
(a) Full penetration welds shall be used.
(b) Where only two welds are used, the minimum weld spacing shall be 152 mm (6 in.). Where more than two welds arc required, minimum weld spacing shall be 609 mm (24 in.). Weld spacing shall be measured along the inside circumference of the metal core. When material availability precludes this weld spacing, then additional welding, as agreed by the purchaser and manufacturer, is permitted.
(C) The grooves shall be machined into the core after welding.
(d) In welded areas, the groove, peak prouile. and base metal shall be uniform in spacinR. thickness, and height with the adjacent metal core.
(e) When specified by the purchaser. weld inspection methods, such as ultrasonic or radiographic. along with acceptance criteria, shall be established.
5.2.4 Centering Ring. A centering ring is required and uwd to help position the gasket within the Ihinge bolt circle. Unless otherwise specified by the purchaser, the centering ring shall be 1.6-mm (0.06-in.) nominal thickness and shall be suitably attached to the grooved metal core using an integral (one-piece or welded) or nonintegral attachment method. The thickness of the centering ring shall not exceed the thickness of the core.