... -- pressure-locked C-- socket-weldingBearing bar centers:15-30, 40, 60, 80, 90 mm etc. with 30, 40 ... recommended.Cross bar centers:any greater than 30mm is ok. with 50, 100mm recommended.Surface treatment:G - galvanizedP - ... the cover and the frame are connected with hinges, so it's convenient for opening- up and very safe.4 ... , please contact us. steel grating rain draining system for municipal service