steel drainage grating 1.ISO9001--2008 2.Export to more than 30 countries 3.10 years factory 4.Professiona Steel Drainage Grating:Steel Drainage Grating Application:Widely used in electricity, petrochemical, chemical industry, metallurgy, machines, modeling, port, marine engineering, construction, papermaking, medicine, textile, well cover, suspended ceiling, ventilation and penetration of light, ...