Improvements relating to manhole doors and manholes

摘要

546,071. Manhole doors. SHENTON, R. Aug. 13, 1941, No. 10281. [Class 123 (i)] A manhole in the top plate a of a ballast tank is provided with two rings b, c welded or riveted to it. The lower ring serves as a seating for a cover d which carries upwardly projecting bolts e passing through holes in the ring c and provided with nuts above that ring. No part of the cover or its securing means projects above the tank top.