The outside diameter and drilling template of flanges shall be in accordance with ASME B16.5 Class 150, Class 300 or Class 600, depending upon the specified pressure class. The flange face shall be flat-type. Both loose and fixed flanges are accepted. However, loose metal flanges or heavy duty GRE/GRVE flanges shall be used when connected to a wafer type valve or to raced face flanges of equipment nozzles. Loose flange may be carbon steel (ASTM A105 or equivalent), hot dip galvanized in accordance with ASTM A153 (or equivalent coatings in accordance with BS 729 or NS 1970).

For diameters above DN 600 mm (24 inch) reference is made to MSS SP-44

Orifice flange
The outside diameter and drilling template of flanges shall be in accordance with ASME B16.36 Class 300 or Class 600, depending upon the specified pressure class. The flange face shall be flat-type.

Spectable blind and spade
Spectable blind or spade shall be flat face-type.