... steel frame parts are all processed with anti-corrosion coating and can be used for as long as 50 years5, ... , square tube , steel angle ,tie bar,tendsion rod and bracing. 3.Doors and windowsComposite panel ,roller doors.PVC window, aluminum alloy window ... 4.Roof and wall materials Semi-transparent skylight belts, Ventilators, down pipe etcCorrugated ...