... public diameter: 6 ~ 4000mm c, Flange structure type: welding, socket welding, threaded connection, loose, butt weld and blind flange d ... flange Unit flange a, threaded flange b, welding flange, welding neck flange, welding neck flange, socket weld flange with neck , ... , flange cover (blind flange) e, Rotating flange f, Anchor Flange g, Surfacing / Cover welding flange 4) Flange sealing surface: flat ...