... .Material: SS304/SS316L 3.Certificate:ISO9001:2000 (sanitary manhole cover, manway cover) Export to North America and Europ market since 1996, ... under the temperature of 20°C)YAC-1:arc manhoe cover,has higher bracket,suitable for big vessels with lagging material ... .YAC:flat manhole cover,lower bracket.YAC:flat manhole over,,higher bracket,suitable for ...