6793: Other tubes, pip., circ. cross-s., ext. dia.>406, 4mm

67931: Line pipe of a kind used for oil or gas pipeline 67932: Casing of a kind used in the drilling for oil, gas 67933: Other tubes & pipes, welded, external diame.>406, 4mm 67939: Other tubes & pipes, n.e.s., external diame.>406, 4mm 6793: Other tubes, pip., circ. cross-s., ext. dia.>406, 4mm