... apart,by welding with 200-ton hydraulic resistance automatic welding equipment,then cutting,punching and banding ends .1>Steel ... appearance,bright surface 4.No dirt-rain-snow deposit,automatic cleaning,eay maintenance5.Good ventilation,day-lighting,heat- ... industry,electric power,water supply,sweat treatment,ship building,parking lots,city construction,environmental ingineering .Steel grating pictures: ...