... (DIN ST37ST42) standard ST52 International (GB) T8162, T8163, T3087, 10#20# specification 1/ 2" -34", SCH10-SCHXXX wall thickness. 1 general ... Seamless steel pipes conveying fluid GB / T8163-1999, grades: 10,20, # #, specifications:6-720* 1-70mm 11 Low and medium pressure ... boiler pipe steel grade GB3087-1999, 10, 20: # #, specifications: 6-720* 1-70mm 12 High pressure boiler tube ...