... good quality and competitive price 3,ISO cert 4,quick delivery constrution use hot dip galvanized square and rectangular steel pipe/ ... need.4. Surface treatment: bared, galvanized, oiled, painted to prevent rust.5. Technique: ERW, hot-rolled6. Certification: CE, ISO7. Material ... , EN10219-2:2006 JISG3466-889. Application: square steel pipe are widely used in machine-building, construction, metallurgy, ...