The connection between the plastic tube and the metal tube seems not so simple
Plastic pipes with outer diameter as standard, usually 20, 32, 40, 50, 60, 70, 110, etc., all with inner diameter and corresponding wall thickness
The pipe you want to connect can be connected by the corresponding joint. It's simple
Steel pipe with inner diameter of the standard specifications for 15 and 25, usually 32, 50, 65, 100 and so on, and the wall thickness and the corresponding plastic tube almost, therefore, regardless of the flange or is connected inside or outside the wire of plastic pipe and steel pipe is no problem
