General – Steps in the bulkhead deck
1 If the transverse watertight bulkheads in a region of the ship are carried to a higher
deck which forms a vertical step in the bulkhead deck, openings located in the bulkhead
at the step may be considered as being located above the bulkhead deck. Such openings
should then comply with regulation 17 and should be taken into account when applying
regulation 7-2.
2 All openings in the shell plating below the upper deck throughout that region of the
ship should be treated as being below the bulkhead deck and the provisions of regulation
15 should be applied. See figure below.
Regulation 13.2.3
1 For closed piping systems compliance with this regulation is achieved if
approved pipe penetrations are fitted at the crossing of watertight boundaries to ensure
that heat-sensitive pipes outside the space affected by the fire remain intact, so that
any flooding of the fire affected space does not cause progressive flooding through the
piping or pipe penetration.
1.1 For open piping systems compliance with this regulation is achieved if
approved pipe penetrations are fitted at the crossing of watertight boundaries as are
required for closed piping systems, and additionally each pipe connection to a
watertight compartment is fitted with an isolation or non-return valve, as appropriate,
to prevent progressive flooding through the piping system after a fire. As an
alternative to fitting an isolation or non-return valve, pipes may be routed above the
damaged waterline in such a way that progressive flooding is prevented, taking into
account the dynamic movements of the ship in a damaged condition.
1.2 However, progressive flooding may be taken into account in accordance
with regulation 7-2.5.4 instead.
2 For the purpose of this explanatory note the following definitions apply:
3 Materials used in systems which penetrate watertight boundaries should be
of sufficient strength after exposure to heat or be considered as part of an open piping
system. Closing devices using intumescent material (swelling when exposed to heat) for
open piping systems should not be considered equivalent to the fitting of a valve, since
the fire might be located too far from the device to create a watertight seal.
4 Approval of pipe penetrations fitted to ensure the watertight integrity of
a bulkhead or deck where heat-sensitive materials are used should include a prototype
test of watertightness after having undergone the standard fire test appropriate for the
location in which the penetrations are to be installed.footnote
4.1 The fire tested pipe penetration should then be tested to a test pressure
of not less than 1.5 times the design pressure as defined in regulation 2.18. The
pressure should be applied to the same side of the division as the fire test.
4.2 The fire tested pipe penetration should be tested for a period of at
least 30 min under hydraulic pressure equal to the test pressure, but minimum 1.0 bar.
There should be no leakage during this test.
4.3 The fire tested pipe penetration should continue to be tested for a
further 30 min with the test pressure. The quantity of water leakage is not to exceed a
total of 1 litre.
4.4 The prototype test should be considered valid only for the pipe typology
(e.g. thermoplastic and multilayer), pressure classes, the maximum/minimum dimensions
tested, and the type and fire rating of the division tested.
5 The pressure test need not be carried out on the hot penetration arrangement. Ample
time may be given to prepare for the pressure test, i.e. dismantling the fire testing
equipment and rigging the pressure test equipment.
5.1 The pressure test should be carried out with the pipe section used in
the fire test still in place.
5.2 Any pipe insulation fitted for the purpose of the fire test may be
removed before the pressure test.
5.3 Prototype testing need not be carried out if the pipe penetration is
made of steel or equivalent material having a thickness of 3 mm or greater and a length
of not less than 900 mm (preferably 450 mm on each side of the division), and there are
no openings. Such penetrations shall be suitably insulated by extension of the
insulation at the same level of the division. See also regulation II-2/9.3.1 with
respect to piping. However, the penetration must still comply with the watertight
integrity requirement in regulation 2.17.
Regulation 13.4
In cases where main and auxiliary propulsion machinery spaces, including boilers serving
the needs for propulsion, are divided by watertight longitudinal bulkheads in order to
comply with redundancy requirements (e.g. according to regulation 8-1.2), one watertight
door in each watertight bulkhead may be permitted, as shown in the figure below.
