1 Tank connection space for tanks on open deck and tank connection
space equipment (paragraph 2.2.15.3)
1.1 A tank connection space may be required also for tanks on open deck.
This may apply for ships where restriction of hazardous areas is safety critical. A
tank connection space may also be necessary in order to provide environmental
protection for essential safety equipment related to the gas fuel system like tank
valves, safety valves and instrumentation.
1.2 A tank connection space may also contain equipment such as vaporizers
or heat exchangers. Such equipment is considered to only contain potential sources
of release, but not sources of ignition.
2 Fuel preparation room (paragraph 2.2.17)
A tank connection space which has equipment such as vaporizers or heat exchangers
installed inside is not regarded as a fuel preparation room. Such equipment is
considered to only contain potential sources of release, but not sources of
ignition.
3 Appropriate location of premixed engines using fuel gas mixed with air before
the turbocharger (paragraph 5.4.1)
Premixed engines using fuel gas mixed with air before the turbocharger should be
located in ESD-protected machinery spaces.
4 Protection against cryogenic leakage and control of hazardous zones in fuel
preparation rooms on open deck (paragraphs 5.8 and 6.2.1.1)
4.1 Fuel preparation rooms, regardless of location, should be arranged to safely
contain cryogenic leakages.
4.2 The material of the boundaries of the fuel preparation room should have a design
temperature corresponding with the lowest temperature it can be subjected to in a
probable maximum leakage scenario unless the boundaries of the space, i.e. bulkheads
and decks, are provided with suitable thermal protection.
4.3 The fuel preparation room should be arranged to prevent surrounding hull
structure from being exposed to unacceptable cooling, in case of leakage of
cryogenic liquids.
4.4 The fuel preparation room should be designed to withstand the maximum pressure
build up during such a leakage. Alternatively, pressure relief venting to a safe
location (mast) can be provided.
5 External surface area of the tank for determining sizing of pressure relief
valve (paragraph 6.7.3.1.1.2 and figure 6.7.1)
For prismatic tanks
5.1 Lmin, for non-tapered tanks, is the smaller of the horizontal
dimensions of the flat bottom of the tank. For tapered tanks, as would be used for
the forward tank, Lmin is the smaller of the length and the average
width.
5.2 For prismatic tanks whose distance between the flat bottom of the tank and bottom
of the hold space is equal to or less than L
min/10:
|
A |
= |
external surface area minus flat bottom surface area. |
5.3 For prismatic tanks whose distance between the flat bottom of the tank and bottom
of the hold space is greater than L
min/10:
|
A |
= |
external surface area. |
6 Control and maintenance of pressure and temperature of liquefied gas fuel tanks
after the activation of the safety system (paragraphs 6.9.1.1 and
6.9.1.2)
Liquefied gas fuel tanks' pressure and temperature should be controlled and
maintained within the design range at all times including after activation of the
safety system required in 15.2.2 for a period of minimum 15 days. The activation of
the safety system alone is not deemed as an emergency situation.
7 Special consideration within the risk assessment of closed or semi-enclosed
bunkering stations (paragraph 8.3.1.1)
The special consideration should as a minimum include, but not be restricted to, the
following design features:
- segregation towards other areas on the ship
- hazardous area plans for the ship
- requirements for forced ventilation
- requirements for leakage detection (e.g. gas detection
and low temperature detection)
- safety actions related to leakage detection (e.g. gas
detection and low temperature detection)
- access to bunkering station from non-hazardous areas
through airlocks
- monitoring of bunkering station by direct line of sight
or by CCTV.
8 Ventilation of machinery spaces (paragraph 13.5.1)
Spaces enclosed in the boundaries of machinery spaces (such as purifier's room,
engine-room workshops and stores) are considered an integral part of machinery
spaces containing gas-fuelled consumers and, therefore, their ventilation system
does not need to be independent of the one of machinery spaces.
9 Ventilation of double piping and gas valve unit spaces in gas safe engine-rooms
(paragraph 13.8.2)
Double piping and gas valve unit spaces in gas safe engine-rooms are considered an
integral part of the fuel supply systems and, therefore, their ventilation system
does not need to be independent of other fuel supply ventilation systems provided
such fuel supply systems contain only gaseous fuel.
10 Ventilation inlet for double wall piping or duct (paragraph 13.8.3)
The ventilation inlet for the double wall piping or duct should always be located in
a non-hazardous area in open air away from ignition sources.