Regulation 12.6.1
For cargo ships, the following figures show examples of suitable butterfly valve
arrangements:
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Figure 1
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Figure 2
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As butterfly valves must be capable of being remotely operated the following shall
apply:
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.1 the actuator shall be of a double acting type;
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.2 when subject to loss of power, the actuator shall remain in its current
position; and
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.3 when subject to loss of power, the valve shall be able to be manually
operated.
Regulation 12.10
1 In cargo ships the after engine room bulkhead can be regarded as the
afterpeak bulkhead provided that the after peak adjoins the engine-room.
2 In cargo ships with a raised quarter deck, it may be impracticable to extend the
afterpeak bulkhead to the freeboard deck as the freeboard deck does not extend to the
aft perpendicular. Provided that the afterpeak bulkhead extends above the deepest load
line, and that all rudderstock bearings are housed in a watertight compartment without
open connection to spaces located in front of the afterpeak bulkhead, termination of the
afterpeak bulkhead on a watertight deck lower than the freeboard deck can be accepted by
the Administration.

Regulation 12.11
In cargo ships a stern tube enclosed in a watertight space of moderate volume, such as an
afterpeak tank, where the inboard end of the stern tube extends through the
afterpeak/engine room watertight bulkhead into the engine room is considered to be an
acceptable solution satisfying the requirement of this regulation, provided the inboard
end of the stern tube is effectively sealed at the afterpeak/engine room bulkhead by
means of an approved watertight/oiltight gland system.