ASME B16.5-2013 pdf – Pipe Flanges andFlanged Fittings NPS 1/2 Through NPS 24Metric/Inch Standard.
6.4 Flange Facings
6.4.1 General. Figure 6 (Fig. 11-6 of Mandatory Appendix II) shows dimensional relationships for various flange types and pipe lap facings to be used with lap joints. Table 4 (Table 11-4 of Mandatory Appendix 11) lists dimensions for facings other than ring joint. Table 5 (Table 11-5 of Mandatory Appendix II) lists dimensions for ring joint facings. Classes 150 and 300 pipe flanges and companion flanges of fittings are regularly furnished with 2 mm (0.06 in.) raised face, which is in addition to the minimum flange thickness, tf. Classes 400, 600, 900, 1500, and 2500 pipe flanges and companion flanges of fittings are regularly furnished with 7 mm (0.25 in.) raised face, which is in addition to the minimum flange thickness, t1.
6.4.2 Other Than Lapped Joints. For joints other than lapped joints, the requirements of paras. 6.4.2.1 and 6.4.2.2 shall apply.
6.4.2.1 Raised Face and Tongue Face. In the case of flanges having raised face, tongue, or male face, the minimum flange thickness, tf, shall be provided, and then the raised face, tongue, or male face shall be added thereto.
6.4.2.2 Grooves. For flanges that have a ring joint, groove, or female face, the minimum flange thickness shall first be provided and then sufficient thickness added thereto so that the bottom of the ring joint groove, or the contact face of the groove or female face, is in the same plane as the flange edge of a full thickness flange.
6.4.3 Lapped Joint Flanges. Lapped joint flanges shall be furnished with flat faces as illustrat ed in Tables 8, 11, 14, 16, 18, 20, and 22 (Tables 11-8, 11-11, 11-14, 11-16, 11-18, 11-20, and 11-22 of Mandatory Appendix II). Lap joint stub ends shall be in accordance with Fig. 6 (Fig. 11-6 of Mandatory Appendix II) and paras. 6.4.3.1 through 6.4.3.3.
6.4.3.1 Raised Face. The finished thickness of the lap shall be no less than nominal pipe wall thickness.
6.4.3.2 Large Male and Female. The finished height of the male face shall be the greater of the wall thickness of the pipe used or 7 mm (0.25 in.). The thickness of lap that remains after machining the female face shall be no less than the nominal wall thickness of pipe used.
6.4.3.3 Tongue and Groove. The thickness of the lap remaining after machining the tongue or groove face shall be no less than the nominal wall thickness of the pipe used.
6.4.3.4 Ring Joint. The thickness of the lap remaining after machining the ring groove shall be no less than the nominal wall thickness of pipe used.
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6.4.5 Flange Facing Finish. Flange facing finishes shall be in accordance with paras. 6.4.5.1 through 6.4.5.3, except that other finishes may be furnished by agreement between the user and the manufacturer. The finish of the gasket contact faces shall be judged by visual comparison with Ra standards (see ASME B46.1) and not by instruments having stylus tracers and electronic amplification.
6.4.5.1 Tongue and Groove and Small Male and Female. The gasket cont act surface finish shall not exceed 3.2 f.Lm (125 fLin.) roughness.
6.4.5.2 Ring Joint. The side wall surface finish of the gasket groove shall not exceed 1.6 fLm (63 fLin.) roughness.
6.4.5.3 Other Flange Facings. Either a serrated
concentric or serrated spiral finish having a resultant surface finish from 3.2 f,Lm to 6.3 f.Lm (125 fLin. to 250 fLin.) average roughness shall be furnished. The cutting tool employed should have an approximate 1.5 mm (0.06 in.) or larger radius, and there should be from 1.8 grooves/ mm through 2.2 grooves/mm (45 grooves/in, through 55 grooves/in.).
6.4.6 Flange Facing Finish Imperfections. Imperfections in the flange facing finish shall not exceed the dimensions shown in Table 3 (Table 11-3 of Mandatory Appendix II). A distance of at least four times the maximum radial projection shall separate adjacent imperfections. A radial projection shall be measured by the difference between an outer radius and inner radius encompassing the imperfection where the radii are struck from the centerline of the bore. Imperfections less than half the depth of the serrations shall not be considered cause for rejection. Protrusions above the serrations are not permitted.