name: steel bend material: carbon steel A234 WPB ANSI B16.9 standard: ASTM, ASME, GB, JIS,DIN, BS ISO9001/9002 ASTM A106/A53 Gr.B Seamless Carbon Steel PipeOD 21 ... )Surface TreatmentLight varnish, black oilStandardAPI,ASTM ANSI,ASME,GB,DIN,BS Grade10#,20#,45#,A53,A106,A312Surface treatmentblack rust-proof oil, transparent ... goods, you can contract me directly. Welcome to your inquiry. steel pipe