As for machining to iron and steel castings, the surface finish smooth degree is also an important requirement. The serrations should be on the same level, and the protrusion above them is not permitted. The standard finishes for required level of average roughness height on the flange face are described below. // -->, ASME Y14.36M - 1996 Surface Texture Symbols, ISO 468:1982 “Surface roughness — parameters. root of 2 or 1.414 except in the sizes Nos. • Flange to the old DIN standard are compatible to the new DIN EN 1092-1. RMS = Root Mean Square in micro-inches AARH is the average height of irregularities, on the surface under observation, from the mean line as shown in the following figure. For the H atom, En = -2.18x10-18 J/n2. GD&T Training Geometric Dimensioning Tolerancing A–C. The information contained in the table is based on the assumption that metal surfaces are being tested. Rp = R a x 3.6 The surface finishes produce desired roughness at the face of a flange which ensures that it is compatible with the gasket and provides high-quality sealing. PN 58/M 042-51, CHINA