... ASTM 4)Section Shape: Round Dingrun S355JR Seamless Steel Tubes And Pipes1)Business Type: Manufacture and sale2) ... steel tubes include 10#, 20#, 35#, 45#, 160Mn, 20GrMo, 35GrMo, 40Gr. The products have the characteristics of small-sized, heavy-wall thickness, high precision ... advanced manufacturing technique and equipments, implements ISO9001 quality system codes, operates effective management model, ...