| 摘要 |
A manhole cover for a circular opening in the wall of a tank comprises a case 12 surrounding the opening 11 and projecting beyond the wall, which is surrounded by a few stud bolts 16 fastened to the wall just outside the case and connected to it by a vertical, radially oriented washer 17. A flat cover 13 is provided on its bottom side with a circular packing holder 21 with inverted U-shaped cross section. The groove 22 in the packing holder is adapted to straddle the upper edge of the case, and is designed to secure a packing 23 which has less thickness than the depth of the groove. <IMAGE> |
