Size flat welding flange: 3/8 "to 40" DN10 ~~ DN1000 pressure the United States Series: CLASS 150, CLASS 300, CLASS 400, CLASS 600, CLASS 900, CLASS 1500, CLASS 2500 European Series: PN 2.5, PN 6, PN 10, PN 16, PN 25, PN 40, the PN 63, a PN 100, the PN 160, the PN 250, a PN 320 and PN 400 flange sealing surface type US Series: plane (FF), the groove surface (G), the convex surface ( MFM)