... 16aa) 2.WT: 3~30mm 3.ISO Standard,API certificate astm structural seamless steel pipe SpecificationOD 33mm - 406mm(1”~16”) with thickness of 3 ... ), 16mn(STS49,STPT49) etc.c. ASTM/AISI Standard10#(ASTM a106/53 Gr.B,A192,A179-C),20#(ASTM A106/53 Gr.B, A178-C,A210-A-1,A315 ... -B,AISI1020),45#(AISI1045), 16mn(ASTM A210-C) ...