... elbow is used to be installed between two lengths of pipe or tube allowing ... "---48"THICKNESS:STD,SCH40,SCH20,SCH60,SCH80,SCH100,S , CH120,SCH160,XS,XXS,SGP, ETC.carbon ... a central axis (centerline) of the section between the large and small.b. Eccentric reducer: the central axis ... different (offset) between a large section and small.Concentric reducer is most commonly used and often eccentric reducer ...