1625-0036 Stat/Authority

§ 157.500

33 CFR Ch. I (7–1–01 Edition)

Subpart H—Interim Measures for
Certain Tank Vessels Without
Double Hulls Carrying Animal
Fat or Vegetable Oil
SOURCE; CGD 91–045, 61 FR 39791, July 30,
1996, unless otherwise noted.

§ 157.500 Purpose and applicability.
(a) The purpose of this subpart is to
establish mandatory safety and operational requirements to reduce environmental damage resulting from the
discharge of animal fat or vegetable
oil.
(b) This subpart applies to each tank
vessel specified in § 157.01 of this part
that—
(1) Is 5,000 gross tons or more;
(2) Carries animal fat or vegetable oil
in bulk as cargo or cargo residue; and
(3) Is not equipped with a double hull
meeting § 157.10d of this part, or an
equivalent to the requirements of
§ 157.10d, but required to be equipped
with a double hull at a date set forth in
46 U.S.C. 3703a (b)(3) and (c)(3).
§ 157.510 Operational measures.
An owner or operator of a tank vessel
that carries animal fat or vegetable oil
in bulk as cargo or cargo residue shall
comply with the requirements in all
sections of subpart G of this part.

Subpart I—Interim Measures for
Certain Tank Vessels Without
Double Hulls Carrying Other
Non–Petroleum Oil
SOURCE; CGD 91–045, 61 FR 39791, July 30,
1996, unless otherwise noted.

§ 157.600 Purpose and applicability.
(a) The purpose of this subpart is to
establish mandatory safety and operational requirements to reduce environmental damage resulting from the
discharge of other non-petroleum oil.

(b) This subpart applies to each tank
vessel specified in § 157.01 of this part
that—
(1) Is 5,000 gross tons or more;
(2) Carries other non-petroleum oil in
bulk as cargo or cargo residue; and
(3) Is not equipped with a double hull
meeting § 157.10d of this part, or an
equivalent to the requirements of
§ 157.10d, but required to be equipped
with a double hull at a date set forth in
46 U.S.C. 3703a (b)(3) and (c)(3).
§ 157.610

Operational measures.

An owner or operator of a tank vessel
that carries other non-petroleum oil in
bulk as cargo or cargo residue shall
comply with the requirements in all
sections of subpart G of this part.
APPENDIX A TO PART 157—DAMAGE ASSUMPTIONS,
HYPOTHETICAL
OUTFLOWS, AND CARGO TANK SIZE AND
ARRANGEMENTS
1. Source. The procedures for the damage
assumption calculations contained in this
Appendix conform to Regulations 22, 23, and
24 of Annex I of the International Convention for the Prevention of the Pollution from
Ships, 1973, done at London, November 2,
1973.
2. Assumptions. For the purpose of calculating hypothetical outflow from tank vessels, three dimensions of the extent of damage of a parallelepiped on the side and bottom of the vessel are assumed.
(a) For side damage, the conditions are as
follows:
Damage

Conditions

(1) Longitudinal extent lc ..............
(2) Transverse extent (tc) (inboard
from the vessel’s side at right
angles to the centerline at the
level corresponding to the assigned summer freeboard).
(3) Vertical extent (vc) ..................

⁄ L2/3 or 14.5 m, whichever is less.
B
—or 11.5 m, whichever
is 5 less.

13

From the base line upwards without limit.

(b) For bottom damage, two conditions to
be applied individually to the stated portions
of the vessel, as follows:
Conditions

Damage
(1) Longitudinal extent (l s) .................
(2) Transverse extent (t s) ..................
(3) Vertical extent from the base line
(vs).

For 0.3L from the forward perpendicular of ship

Any other part of ship

L/10 ........................................................................
B/6 or 10 meters, whichever is less but not less
than 5 meters.
B/15 or 6 meters, whichever is less ......................

L/10 or 5 meters, whichever is less.
5 meters.
B/15 or 6 meters, whichever is less.

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Coast Guard, DOT

Pt. 157, App. A

3. Hypothetical Outflow of Oil. (a) The hypothetical outflow of oil in the case of side
damage (Oc) and bottom damage (Os) is calculated by the following formula with respect to compartments breached by damage
to all conceivable locations along the length
of the vessel to the extent as defined in section 2 of this Appendix.
(1) For side damages: Formula
Oc = Σ Wi+Σ KiCi
(2) For bottom damage: Formula II
Os = 1⁄3(Σ ZiWi+Σ ZiCi)
Where:
Wi=Volume of a wing tank assumed to be
breached by the damage as specified in section 2 of this Appendix; Wi for a segregated
ballast tank may be taken equal to zero;
Ci=Volume of a center tank assumed to be
breached by the damage as specified in section 2 of this Appendix; Ci for a segregated
ballast tank may be taken equal to zero;

Ki = 1−

bi
tc

when bi is equal to or greater than tc, Ki is
equal to zero;

Zi = 1 −

hi
vs

when hi is equal to or greater than vs, Zi is
equal to zero;
bi=Minimum width of wing tank under consideration measured inboard from the vessel’s side at right angles to the centerline
at the level corresponding to the assigned
summer freeboard; and
hi=Minimum depth of the double bottom
under consideration; where no double bottom is fitted, hi is equal to zero.
(b) If a void space or segregated ballast
tank of a length less than lc is located between wing oil tanks, Oc in formula I of this
section may be calculated on the basis of
volume Wi being the actual volume of one
such tank (where they are of equal capacity)
or the smaller of the two tanks (if they differ
in capacity), adjacent to such space, multiplied by Si as defined below and taking for
all other wing tanks involved in such a collision the value of the actual full volume.

Si = 1 −

li
lc

Where li=length of void space or segregated
ballast tank under consideration.
(c) Credit is only given in respect to double
bottom tanks which are either empty or carrying clean water when cargo is carried in
the tanks above.
(1) If the double bottom does not extend for
the full length and width of the tank involved, the double bottom is considered non-

existent and the volume of the tanks above
the area of the bottom damage must be included in formula II of this section even if
the tank is not considered breached because
of the installation of such a partial double
bottom.
(2) Suction wells may be neglected in the
determination of the value hi if such wells
are not excessive in area and extend below
the tank for a minimum distance and in no
case more than half the height of the double
bottom. If the depth of such a well exceeds
half the height of the double bottom, hi is
taken equal to the double bottom height
minus the well height.
(d) In the case where bottom damage simultaneously involves four center tanks, the
value of Os may be calculated according to
formula III as follows:
Os = 1⁄4(Σ ZiWi+Σ ZiCi)
(e) Credit for reduced oil outflow from bottom damage may be applied to formula III
for an installed emergency high suction
cargo transfer system that:
(1) transfers within two hours oil equal to
one half of the volume of the largest tank involved;
(2) has sufficient ballast or cargo tankage
available to receive the transferred oil; and
(3) has the high suction piping installed at
a height not less than the vertical extent of
bottom damage (vs).
4. Allowable volumes of cargo tanks.
(a) The allowable volume of a wing cargo
tank (VOLw) is equal to seventy-five percent
of OA. In a segregated ballast tank vessel
VOLw may equal OA for a wing cargo oil
tank located between two segregated ballast
tanks each of length greater than lc and
width greater than tc.
(b) The allowable volume of a center cargo
tank (VOLc) is 50,000 cubic meters.
5. Allowable length of cargo tanks.
The length of each cargo tank (1 a) must
not exceed 10 meters or the distance calculated from (a), (b), or (c), as appropriate,
whichever is greater:
(a) Where no longitudinal bulkhead is provided inside the cargo tanks: 1 a=[0.5(bi/
B)+0.1] L, but not to exceed 0.2L.
(b) Where a centerline longitudinal bulkhead is provided inside the cargo tanks: 1
a=[0.25(bi/B)+0.15] L, but not to exceed 0.2L.
(c) Where two or more longitudinal bulkheads are provided inside the cargo tanks:
(1) For wing cargo tanks: 1 a = 0.2L.
(2) For center cargo tanks:
(i) If (bi/B) is equal to or greater than 0.2,
1 a = 0.2L.
(ii) If (bi/B) is less than 0.2:
(A) Where no centerline longitudinal bulkhead is provided, 1 a = [0.5(bi/B) + 0.1] L.
(B) Where a centerline longitudinal bulkhead is provided, 1 a = [0.25(bi/B) + 0.15] L.

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Pt. 157, App. B

33 CFR Ch. I (7–1–01 Edition)

(d) ‘‘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 centerline at the
level corresponding to the assigned summer
freeboard.
[CGD 74–32, 40 FR 48283, Oct. 14, 1975, as
amended by CGD 74–32, 40 FR 49328, Oct. 22,
1975; CGD 90–051, 57 FR 36245, Aug. 12, 1992]

APPENDIX B TO PART 157—SUBDIVISION
AND STABILITY ASSUMPTIONS
1. Source. The procedures for the loading
assumption calculations contained in this
Appendix conform to Regulation 25 of Annex
I of the International Convention for the
Prevention of the Pollution from Ships, 1973,
done at London, November 2, 1973.
2. Loading Assumptions. For the purpose of
calculating subdivision and damage stability
for a tank vessel, the operating drafts must
reflect actual partial or full load conditions
consistent with trim and strength of the vessel. Ballast conditions need not be considered if the tank vessel is not carrying oil in
cargo tanks excluding oily residues. Loading
condition must reflect the specific gravities
of the cargo.
3. Damage Assumptions.
(a) Damage is applied to all conceivable locations along the length of the vessel as follows:
(1) For a vessel of more than 225 meters in
length, anywhere in the vessel’s length.
(2) For a vessel of more than 150 meters,
but not exceeding 225 meters in length, anywhere in the vessel’s length except where the
after or forward bulkhead bounding a machinery space located aft is involved in the
damage assumption. The machinery space is
calculated as a single floodable compartment.
(3) For a vessel 150 meters or less in length,
anywhere in the vessel’s length between adjacent transverse bulkheads except the machinery space.
(b) The extent and the character of the assumed side or bottom damage, as defined in
section 2 of Appendix A of this part, must be
applied except longitudinal bottom damage
within 0.3L from the forward perpendicular
must be assumed to be the same as that for
side damage. If any damage of lesser extent
results in a more severe condition, such damage must be assumed.
(c) If damage involves transverse bulkheads as specified in paragraphs (a)(1) and (2)
of this section, transverse watertight bulkheads must be spaced at least at a distance
equal to the longitudinal extent of the assumed damage specified in paragraph (b) of
this section in order to be considered effective. Where transverse bulkheads are spaced
at a lesser distance, one or more of these
bulkheads within such extent of damage

must be assumed as nonexistent for the purpose of determining flooded compartments.
(d) If the damages between adjacent transverse watertight bulkheads is within the definition contained in paragraph (a)(3) of this
section, no main transverse bulkhead or a
transverse bulkhead bounding side tanks or
double bottom tanks is to be assumed damaged, unless:
(1) the spacing of the adjacent bulkheads is
less than the longitudinal extent of assumed
damage defined in paragraph (b) of this section; or
(2) there is a step or a recess in a transverse bulkhead of more than 3.05 meters in
length, located within the extent of penetrations of assumed damage. The step formed by
the after peak bulkhead and after peak tank
top is not regarded as a step for these calculations.
(e) If pipes, ducts, or tunnels are situated
within the assumed extent of damage, there
must be arrangements so that progressive
flooding may not thereby extend to compartments other than those assumed to be
floodable for each case of damage.
4. Characteristic and Condition Assumption
for Calculations.
(a) Account must be taken of any empty or
partially filled tanks, the specific gravity of
cargoes carried, and any outflow of liquids
from damaged compartments.
(b) The permeabilities are assumed as follows:
Intended space use

Permeability

Stores ................................................................
Accommodation .................................................
Machinery ..........................................................
Voids ..................................................................
Consumable liquids ...........................................
Other liquids ......................................................

0.60
0.95
0.85
0.95
1 0 or 0.95
2 10 or 0.95

1 Whichever results in the more severe requirements.
2 The permeability of partially filled compartments must be
consistent with actual density and the amount of liquid carried.

(c) The buoyancy of any superstructure directly above the side damage is to be disregarded. The unflooded parts of superstructures beyond the extent of damage may
be taken into consideration if they are separated from the damaged space by watertight
bulkheads and no progressive flooding of
these intact spaces takes place. Class I doors
are allowed in watertight bulkheads in the
superstructure.
(d) The free surface effect is to be calculated:
(1) at an angle of heel of 5 degrees for each
individual compartment; or
(2) by assessing the shift of liquids by moment of transference calculations.
(e) In calculating the effect of free surfaces
of consumable liquids, it is to be assumed
that, for each type of liquid, at least one
transverse pair or a single centerline tank
has a free surface and the tank or combination of tanks to be taken into account is to

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