... advantages such as light weight,high strength,great load-bearing capacity,being economical of materials,ventilation and light admission ... gratings can be classified into two styles by its bearing barstype,namely,plain style and serrated style,according to ... GB/T7001988Hot Galvanizing StandardCHINA GB/T139122002Symbol of Steel Grating1. Bearing bar pitches may be 12.5 152030406080and 90mm,of which ...