Somebody out here no doubt has experience of using Incoloy 625 in process/refinery applications. Can anyone tell me what typical values of hardness for oval ring type joints should be ? ANSI B16.20 does not include Incoloy 625 and therefore no hardness values are listed. All i know is that the gasket should typically be 50HB under the hardness of the mating Incoloy flanges...........but what is that ? Any help would be appreciated.