... 30/100 WFG 1.CERTIFICATE : ISO 9001:2008 quality system certificate INTRODUCTION TO COMMON STEEL GRATINGS: Bearing bar centers at ... platforms, walkway, and stair treads.The products most commonly used for Belt corridor, storage shelf,Attic panel, trestle, guardrail, sunshade ... : single-side full welding every 3 bearing bars. Notes for ordering:1. Please clearly state specifications, types, quantity and ...