Artikel 23

1. This regulation shall apply to oil tankers delivered on or after 1 January 2010, as defined in regulation 1.28.8.
42. For the purpose of this regulation, the following definitions shall apply:
.1 “Load line draught (dS)” is the vertical distance, in metres, from the moulded baseline at mid-length to the waterline corresponding to the summer freeboard to be assigned to the ship. Calculations pertaining to this regulation should be based on draught dS, notwithstanding assigned draughts that may exceed dS, such as the tropical loadline.
.2 “Waterline (dB)” is the vertical distance, in metres, from the moulded baseline at mid-length to the waterline corresponding to 30% of the depth DS.
.3 “Breadth (BS)” is the greatest moulded breadth of the ship, in metres, at or below the deepest load line dS.
.4 “Breadth (BB)” is the greatest moulded breadth of the ship, in metres, at or below the waterline dB.
.5 “Depth (DS)” is the moulded depth, in metres, measured at mid-length to the upper deck at side.
.6 “Length (L)” and “deadweight (DW)” are as defined in regulations 1.19 and 1.23, respectively.
3. To provide adequate protection against oil pollution in the event of collision or stranding the following shall be complied with:
.1 for oil tankers of 5,000 tonnes deadweight (DWT) and above, the mean oil outflow parameter shall be as follows: for combination carriers between 5,000 tonnes deadweight (DWT) and 200,000 m3 capacity, the mean oil outflow parameter may be applied, provided calculations are submitted to the satisfaction of the Administration, demonstrating that after accounting for its increased structural strength, the combination carrier has at least equivalent oil out flow performance to a standard double hull tanker of the same size having a OM < = 0.015. where: OM = mean oil outflow parameter. C = total volume of cargo oil, in m3, at 98% tank filling
.2 for oil tankers of less than 5,000 tonnes deadweight (DWT): The length of each cargo tank shall not exceed 10 m or one of the following values, whichever is the greater: .1 where no longitudinal bulkhead is provided inside the cargo tanks:
.2 where a centreline longitudinal bulkhead is provided inside the cargo tanks:
.3 where two or more longitudinal bulkheads are provided inside the cargo tanks: .1 for wing cargo tanks: 0.2L
.2 for centre cargo tanks: .1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 for wing cargo tanks: 0.2L
.2 for centre cargo tanks: .1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.4 bi is the minimum distance from the ship’s side to the outer longitudinal bulkhead of the tank in question measured inboard at right angles to the centreline at the level corresponding to the assigned summer freeboard.
.1 where no longitudinal bulkhead is provided inside the cargo tanks:
.2 where a centreline longitudinal bulkhead is provided inside the cargo tanks:
.3 where two or more longitudinal bulkheads are provided inside the cargo tanks: .1 for wing cargo tanks: 0.2L
.2 for centre cargo tanks: .1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 for wing cargo tanks: 0.2L
.2 for centre cargo tanks: .1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.1 if
.2 if - where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
- where no centreline longitudinal bulkhead is provided:
- where a centreline longitudinal bulkhead is provided:
.4 bi is the minimum distance from the ship’s side to the outer longitudinal bulkhead of the tank in question measured inboard at right angles to the centreline at the level corresponding to the assigned summer freeboard.
4. The following general assumptions shall apply when calculating the mean oil outflow parameter:
.1 The cargo block length extends between the forward and aft extremities of all tanks arranged for the carriage of cargo oil, including slop tanks.
.2 Where this regulation refers to cargo tanks, it shall be understood to include all cargo tanks, slop tanks and fuel tanks located within the cargo block length.
.3 The ship shall be assumed loaded to the load line draught dS without trim or heel.
.4 All cargo oil tanks shall be assumed loaded to 98% of their volumetric capacity. The nominal density of the cargo oil (ρn) shall be calculated as follows:
ρn = 1000 (DWT)/C (kg/m3)
.5 For the purposes of these outflow calculations, the permeability of each space within the cargo block, including cargo tanks, ballast tanks and other non-oil spaces shall be taken as 0.99, unless proven otherwise.
.6 Suction wells may be neglected in the determination of tank location provided that such wells are as small as practicable and the distance between the well bottom and bottom shell plating is not less than 0.5h, where h is the height as defined in regulation 19.3.2.
5. The following assumptions shall be used when combining the oil outflow parameters:
.1 The mean oil outflow shall be calculated independently for side damage and for bottom damage and then combined into the non-dimensional oil outflow parameter OM, as follows:
OM = (0.4 OMS + 0.6 OMB ) / C
where: OMS = mean outflow for side damage, in m3; and
OMB = mean outflow for bottom damage, in m3.
OMS = mean outflow for side damage, in m3; and
OMB = mean outflow for bottom damage, in m3.
.2 For bottom damage, independent calculations for mean outflow shall be done for 0 m and minus 2.5 m tide conditions, and then combined as follows:
OMB = 0.7 OMB(0) + 0.3 OMB(2.5)
where: OMB(0) = mean outflow for 0 m tide condition; and
OMB(2.5) = mean outflow for minus 2.5 m tide condition, in m3.
OMB(0) = mean outflow for 0 m tide condition; and
OMB(2.5) = mean outflow for minus 2.5 m tide condition, in m3.
6. The mean outflow for side damage OMS shall be calculated as follows:
7. The mean outflow for bottom damage shall be calculated for each tidal condition as follows:
.1 where:
.2 where: i,n, PB(i) and CDB(i) = as defined in subparagraph .1 above;
OB(i) = the outflow from cargo tank i, in m3, after tidal change
i,n, PB(i) and CDB(i) = as defined in subparagraph .1 above;
OB(i) = the outflow from cargo tank i, in m3, after tidal change
.3 The oil outflow OB(i) for each cargo oil tank shall be calculated based on pressure balance principles, in accordance with the following assumptions: .1 The ship shall be assumed stranded with zero trim and heel, with the stranded draught prior to tidal change equal to the load line draught ds.
.2 The cargo level after damage shall be calculated as follows: hc = {(ds + tc- Zl) (ρs) - (1000 p) / g }/ρn where:
.3 For cargo tanks bounded by the bottom shell, unless proven otherwise, oil outflow OB(i) shall be taken not less than 1% of the total volume of cargo oil loaded in cargo tank i, to account for initial exchange losses and dynamic effects due to current and waves.
.4 In the case of bottom damage, a portion from the outflow from a cargo tank may be captured by non-oil compartments. This effect is approximated by application of the factor CDB(i) for each tank, which shall be taken as follows: CDB(i) = 0.6 for cargo tanks bounded from below by non-oil compartments; CDB(i) = 1.0 for cargo tanks bounded by the bottom shell.
.1 The ship shall be assumed stranded with zero trim and heel, with the stranded draught prior to tidal change equal to the load line draught ds.
.2 The cargo level after damage shall be calculated as follows: hc = {(ds + tc- Zl) (ρs) - (1000 p) / g }/ρn where:
.3 For cargo tanks bounded by the bottom shell, unless proven otherwise, oil outflow OB(i) shall be taken not less than 1% of the total volume of cargo oil loaded in cargo tank i, to account for initial exchange losses and dynamic effects due to current and waves.
.4 In the case of bottom damage, a portion from the outflow from a cargo tank may be captured by non-oil compartments. This effect is approximated by application of the factor CDB(i) for each tank, which shall be taken as follows: CDB(i) = 0.6 for cargo tanks bounded from below by non-oil compartments; CDB(i) = 1.0 for cargo tanks bounded by the bottom shell.
8. The probability PS of breaching a compartment from side damage shall be calculated as follows:S of breaching a compartment from side damage shall be calculated as follows:
.1 PS = PSL PSVPST where:
.2 PSa, PSf, PSl, PSu and PSy shall be determined by linear interpolation from the table of probabilities for side damage provided in paragraph 8.3 of this regulation, where: Compartment boundaries Xa, Xf, Zl, Zu and y shall be developed as follows:
.3 Table of probabilities for side damage PSy shall be calculated as follows: PSy = (24.96 -199.6 y/BS) (y/BS) for y/BS ≤ 0.05
PSy = 0.749 + {5 -44.4 (y/BS - 0.05)} (y/BS - 0.05) for 0.05 < y/BS < 0.1
PSy = 0.888 + 0.56 (y/BS - 0.1) for y/BS ≤ 0.1 PSy shall not be taken greater than 1.
PSy = (24.96 -199.6 y/BS) (y/BS) for y/BS ≤ 0.05
PSy = 0.749 + {5 -44.4 (y/BS - 0.05)} (y/BS - 0.05) for 0.05 < y/BS < 0.1
PSy = 0.888 + 0.56 (y/BS - 0.1) for y/BS ≤ 0.1
9. The probability PB of breaching a compartment from bottom damage shall be calculated as follows:
.1 PB = PBL PBTPBV where:
.2 PBa, PBf, PBp, PBs, and PBz shall be determined by linear interpolation from the table of probabilities for bottom damage provided in paragraph 9.3 of this regulation, where: Compartment boundaries Xa, Xf, Yp, Ys, and z shall be developed as follows:
.3 Table of probabilities for bottom damage PBz shall be calculated as follows: PBz = (14.5 - 67 z/DS) (z/DS) for z/DS ≤ 0.1,
PBz = 0.78 + 1.1 (z/DS - 0.1) for z/DS > 0.1. PBz shall not be taken greater than 1.
PBz = (14.5 - 67 z/DS) (z/DS) for z/DS ≤ 0.1,
PBz = 0.78 + 1.1 (z/DS - 0.1) for z/DS > 0.1.
10. This 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 evaluated in accordance with the method described in the Guidelines referred to in regulation 19.5.
11. The following provisions regarding piping arrangements shall apply:
.1 Lines of piping that run through cargo tanks in a position less than 0.30Bs from the ship’s side or less than 0.30Ds from the ship’s bottom shall be fitted with valves or similar closing devices at the point at which they open into any cargo tank. These valves shall be kept closed at sea at any time when the tanks contain cargo oil, except that they may be opened only for cargo transfer needed for essential cargo operations.
.2 Credit 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 with the provisions of the Guidelines referred to in regulation 19.5.