MARPOL Consolidated Edition 2017

Chapter 4 - Requirements for the cargo area of oil tankers
Regulation 24
10 Th is regulation uses a simplified probabilistic approach where a summation is carried out over the
contributions to the mean outflow from each cargo tank. For certain designs, such as those characterized
by the occurrence of steps/recesses in bulkheads/decks and for sloping bulkheads and/or a pronounced hull
curvature, more rigorous calculations may be appropriate. In such cases one of the following calculation
procedures may be applied:
.1 The probabilities referred to in 8 and 9 above may be calculated with more precision through
application of hypothetical sub-compartments.*
.2 The probabilities referred to in 8 and 9 above may be calculated through direct application of the
probability density functions contained in the Guidelines referred to in regulation 19.5 .
. 3 The oil outflow performance may be eva luated in accordance with the method described in the
Guidelines referred to in regulation 19.5.
11 The following provisions regarding pi ping arrangements shall apply:
.1 Lines of piping that run through cargo tanks in a position less than 0.308 5 from the ship's side or
less than 0.300 5 from the ship's bottom shall be fitted with valves or similar closing devices at the
point at which they open into any ca rgo tank. These valves sha ll be kept closed at sea at any time
w hen the tanks contain cargo oil, except that they may be opened only for cargo transfer needed
for essential cargo operations .
. 2 Cred it for reducing oil outflow through the use of an emergency rapid cargo transfer system or
other system arranged to mitigate oil outflow in the event of an accident may be taken into account
only after the effectiveness and safety aspects of the system are approved by the Organization.
Submittal for approval shall be made in accordance w ith the provisions of the Guidelines referred
to in regulation 19.5.
Regulation 24
Damage assumptions
1 For the purpose of calculating hypothetical oil outflow from oil tankers in accordance w ith regulations 25
and 26, three dimensions of the extent of damage of a parallelepiped on the side and bottom oi the ship are
assumed as follows. In the case of bottom damages two conditions are set forth to be applied individually to
the stated portions of the oil tanker .
. 1 Side damage:
.1.1 Longitudinal extent (/cl:
.1.2 Transverse extent (tel
(inboard from the ship's side at
right angles to the centreline at the
level corresponding to the assigned
summer freeboard):
.1.3 Vertical extent (vc):
ftt or 14.5 m, whichever is less
for 11.5 m, whi chever is less
From the baseline upwards w ithout limit
• Refer to Explanatory Notes on matters related to the accidental oil outflow performance (resolution MEPC. 122(52), as amended).
MARPOL CONSOLIDATED EDITION 2017 87