... ANSI B16.9 standard: ASTM, ASME, GB, JIS,DIN, BS ISO9001/9002 ASTM A106/A53 Gr.B Seamless Carbon Steel PipeOD 21 ... (Fixed or Random)Surface TreatmentLight varnish, black oilStandardAPI,ASTM ANSI,ASME,GB,DIN,BS Grade10#,20#,45#,A53,A106,A312Surface ... treatmentblack rust-proof oil, transparent oil, hot galvanizing, 3PE,epoxy coatingEndsplain or threaded with socket or beveled ...