GOST/ГОСТ 12816-80 Standard Flanges for valves,fittings and pipelines for Pnom from 0,1 to 20 MPa (from 1 to 200 kgf/sqsm) General technical requirements Download the PDF    PDF file: GOST 12816 Flanges standard for valves fittings pipelines Pn 0.1 20 MPa technical requirement   GOST/ГОСТ standard flange dimension and weight  GOST/ГОСТ 12836-67 Flange Standard Blind