... for usual structure and machines 3) Model No.: ASTM A106 grade A/B, API 5L, X52, X42, ST52, K55, STK490, STPG, C20 ... ) Foreign standards implemented: DIN, JIS, ASTM (ASME),etcASTM A-106 and ASTM A-53 Grade BChemical composition, %, no moreCMnSiPSCr0.17- 0.240.35 ...