What is the difference between the flange flange connection and the normal flange?

That is, two pipes, pipe fittings or equipment are first fixed on a flange, and between the two flanges, flange mats are fastened together by bolts to complete the connection.

The stainless steel orifice flange is the orifice plate flow meter connected to the orifice plate (the measuring part of the orifice flowmeter) to the pipe, and the two flanges fix the orifice plate in the middle, and the differential pressure is introduced through the pressure tapping point on the flange. On the transmitter, to measure the flow.