Pipes are made of:hot rolled steel strip,cold rolled steel strip(black annealed,bright annealed,full hard).Apply to fluid pipes. standred GBStandardGB/T 3093-2002, GB/T9711GradeQ195-Q345GradeQ235, Q195, Q215Thickness0.5 - 3.0 mmSection ShapeRoundOuter Diameter15 - 89 inchPlace of OriginChinaSecondary Or NotNon-secondaryApplicationFluid PipeTechniqueERWCertificationISO9001Surface TreatmentCR ...