Integral Heavy Weight Drill Pipe The wall thickness of heavy weight drill pipe is between drill pipe and drill collar, its structure is similar with drill pipe. It is made from premium alloyed steel. Its both tool joints and middle upset are welded hardbands. Technical parameters meet with API Spec7-1 Standard. Technical specifications and parameters Size O.D. (in) I.D. (in) Tool Joint O.D. (in) Tool Joint I.D. (in) Connection Max.elevator diameter (in) Central upset dia. (in) Min.drift dia.size(in) 3 1/2 3 1/2 2 1/4 4 3/4 (4 7/8 , 5) 2 1/4 NC38 3 7/8 4 2 2 1/16 2 1/16 1 13/16 4 4 2 1/2 5 1/4 2 1/2 NC40 4 3/16 4 1/2 2 1/4 2 9/16 2 9/16 2 5/16 4 1/2 4 1/2 2 11/16 6 1/4 2 11/16 NC46 4 11/16 5 2 7/16 2 3/4 2 3/4 2 1/2 2 13/16 2 13/16 2 9/16 5 5 3 6 5/8 3 NC50 5 1/8 5 1/2 2 3/4 5 1/2 5 1/2 3 1/4 7 (7 1/4 , 7 1/2) 3 1/4 5 1/2 FH 5 11/16 6 3 3 3/8 3 3/8 3 1/8 3 7/8 3 7/8 3 5/8 4 4 3 3/4 6 5/8 6 5/8 4 8 (8 1/4 , 8 1/2) 4 6 5/8 FH 6 15/16 7 1/8 3 3/4 4 1/2 4 1/2 4 1/4 5 5 4 3/4 All technical specifications and parameters only provides for reference.