Type A marine manhole covers, also known as "rising type" or "oblong protruding" manhole covers, are designed for ship applications where frequent access is not required. They are suitable for inspection access to ship voids, bulkheads, and fuel/water tanks, and are typically watertight and oiltight. Type A covers have a coaming plate and seat ring that are welded together, with the cover projecting above the opening plane by 100mm, according to Hi-Sea Marine.
Drawings of Type A Marine Manhole Covers:

Specification of Type A Marine Manhole Covers:
Type | Nominal size | L1 | L2 | L3 | B1 | B2 | B3 | S | Fastener | Weight |
- | - | mm | Dai | Qut | kg |
A | 450x350 | 450 | 470 | 570 | 350 | 370 | 470 | 4
6
8
10 | M20 | 16 | 23.2
30.8
36.9
45.8 |
A | 600x400 | 600 | 620 | 720 | 400 | 420 | 520 | 6
8
10
12 | M20 | 20 | 48.8
59.2
69.3
79.6 |
A | 800x600 | 800 | 820 | 920 | 600 | 620 | 720 | 8
10
12
14 | M20 | 26 | 52.4
65.8
78.2
90.2 |