... The public diameter: 6 ~ 4000mm c, Flange structure type: welding, socket welding, threaded connection, loose, butt weld and blind flange d, ... : Integral flange Unit flange a, threaded flange b, welding flange, welding neck flange, welding neck flange, socket weld flange with neck , slipon ... -91~HGJ65-91\HG20592-97series\HG20615-97series Ministry of Machinery standards:JB81-59~JB86-59\JB/T79-94~JB/ ...