Flange facings under GOST 33259: types A, B, E/F and others
The gate valve arrives and the flanges will not mate: the pipe flange has a tongue, the valve has a raised face. It happens when the enquiry gives only DN and PN.
TAZ Engineering Team · · 6 min
Main facing types
Type A is a flat face. Type B is a raised face, the most common for water, steam and petroleum products at moderate pressure. C and D are male and female, E and F are tongue and groove: these pairs are used together and hold the gasket better at high pressure and with hazardous media. J is for an oval ring-joint gasket at high pressure. The full list is in the tables of the standard.
Older designations
Documents issued before GOST 33259 use the GOST 12815-80 numbering: 1 is a raised face, 2 and 3 male and female, 4 and 5 tongue and groove. When replacing old valves, check the actual flange face on site, not just the number on the drawing.
EN 1092-1 and ASME B16.5
EN 1092-1 also uses letter codes for facing types, but the same letter does not always mean the same face across standards, so always state the standard next to the letter. ASME flanges use RF, FF and RTJ, and their bolt patterns differ from PN flanges.
How to specify
Write it in full, for example "flanges to GOST 33259-2015, type B, PN 16" or "EN 1092-1 type B1, PN 16". If the mating pipe flanges are different, say so: the valve can be made to suit, or supplied with mating flanges, bolts and gaskets.
Checklist
- flange standard
- facing type
- flange PN
- mating pipe flanges
- gasket type
- mating flange kit needed or not