Same answer applies.
UNTIL you KNOW the service conditions (pressure, fluid properties, temperature, and ratings of the pipe and flanges), you CANNOT specify nor purchase the gaskets that will
(1) fit between the gasket faces of the flanges
and (2) protect the fluid and your customer from the pressurized fluids/gasses/steam/HP air inside the pipe..
You're trying to make wrong spec'ed gaskets (metric/DN to ANSI/inches) "fit" the hole around the pipe.
That's the wrong question. And the wrong answer will kill people in future. Maybe. Or maybe not.
Maybe these gaskets are way too strong, too thick, and too expensive. Maybe they'll melt through in 10 minutes. Or maybe not.
You don't know yet.