Ductile iron manhole cover 1)ductile iron QT400/18,QT450/10, ... iron:HT150,HT200,HT250,D400,E600,F9 Ductile iron manhole cover 1)ductile iron QT400/18,QT450/10,QT500/ ... HT200,HT250,D400,E600,F9002)Loading weight of pressure:A15,B125,C250,D400,E600,F9003)Certification of quality:ISO9001:20004) ... ductile iron and grey iron manhole covers and grates 2) We also produce drain cover using steel, stainless steel ...