Ductile iron manhole cover 1)ductile iron QT400/18,QT450/10,QT500/7,QT600/3,QT700/2 Grey iron:HT150,HT200,HT250,D400,E600,F9 Ductile iron manhole cover 1)ductile iron QT400/18,QT450/10,QT500/7,QT600/3,QT700/2 Grey iron:HT150,HT200,HT250,D400,E600,F9002)Loading weight of pressure:A15,B125,C250,D400,E600,F9003)Certification of quality:ISO9001:20004)Main market:Middle East,Africa,Europe,South Korea5 ...