... steel pipecarbon steel pipe carbon seamless steel pipeASTM A106/A53 Gr.B carbon steel seamless pipes Pipe diameter of steel pipe: 10 ... pipe: 6 to 20mm Steel grade of steel pipe: grade B, 20#, Q235, ST 52, ST37 Standards of steel pipe: ASTM ... 53, API 5L, and others Surface of steel pipe oiled or black painted to prevent rust