GOST 12820-80 FLANGE tells you that a valve is a faucet-like thing, or that a faucet is a type of valve. GOST 12820-80 FLANGE tells you that you can unscrew the valve and water or air will flow out; if you can close it, water will stop flowing.

GOST 12820-80 FLANGE tells you that the taps at home are screwed on the pipes with threads, but in some pipes used in the factory, the water or gas inside, the pressure is very high, and the threaded connection is too weak. Just use direct welding, or use other methods to connect. The flange is one such connection method.
GOST 12820-80 FLANGE tells you that there are 2 types of flanges, the basic knowledge of 13 flanges is interpreted, and the knowledge of flanges is systematically learned. The basic introduction of flanges, which includes pipe flanges, gaskets, and fasteners are collectively referred to as flange joints.
The above information is the GOST 12820-80 FLANGE manufacturer's introduction and analysis of the difference between flange and valve, hope it helps you.