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Electronic Code of Federal Regulations

e-CFR data is current as of December 9, 2019

Title 46Chapter ISubchapter SPart 172 → Subpart F


Title 46: Shipping
PART 172—SPECIAL RULES PERTAINING TO BULK CARGOES


Subpart F—Special Rules Pertaining to a Ship That Carries a Hazardous Liquid Regulated Under Subchapter O of This Chapter


Contents
§172.125   Specific applicability.
§172.127   Definitions.
§172.130   Calculations.
§172.133   Character of damage.
§172.135   Extent of damage.
§172.140   Permeability of spaces.
§172.150   Survival conditions.

§172.125   Specific applicability.

This subpart applies to each tankship that carries a cargo listed in Table I of part 153 of this chapter, except that it does not apply to a tankship whose cargo tanks are clean and gas free.

§172.127   Definitions.

Length or L means load line length (LLL).

§172.130   Calculations.

(a) Except as provided in §153.7 of this chapter, each tankship must be shown by design calculations to meet the survival conditions in §172.150 in each condition of loading and operation assuming the damage specified in §172.133 for the hull type prescribed in part 153 of this chapter.

(b) If a cargo listed in Table I of part 153 of this chapter is to be carried, the vessel must be at least the hull type specified in part 153 of this chapter for that cargo.

[CGD 79-023, 48 FR 51040, Nov. 4, 1983, as amended by CGD 81-101, 52 FR 7799, Mar. 12, 1987]

§172.133   Character of damage.

(a) If a type I hull is required, design calculations must show that the vessel can survive damage at any location.

(b) Except as provided in §153.7 of this chapter, if a type II hull is required, design calculations must show that a vessel—

(1) Longer than 492 feet (150 meters) in length can survive damage at any location; and

(2) Except as specified in paragraph (d) of this section, 492 feet (150 meters) or less in length can survive damage at any location.

(c) If a Type III hull is required, design calculations must show that a vessel—

(1) Except as specified in paragraph (d) of this section, 410 feet (125 meters) in length or longer can survive damage at any location; and

(2) Less than 410 feet (125 meters) in length can survive damage at any location except to an aft machinery space.

(d) A vessel described in paragraph (b)(2) or (c)(1) of this section need not be designed to survive damage to a main transverse watertight bulkhead bounding an aft machinery space. Except as provided in §153.7 of this chapter, the machinery space must be calculated as a single floodable compartment.

[CGD 79-023, 48 FR 51040, Nov. 4, 1983, as amended by CGD 81-101, 52 FR 7799, Mar. 12, 1987]

§172.135   Extent of damage.

For the purpose of §172.133—

(a) Design calculations must include both side and bottom damage, applied separately; and

(b) Damage must consist of the penetrations having the dimensions given in Table 172.135 except that, if the most disabling penetrations would be less than the penetrations given in Table 172.135, the smaller penetration must be assumed.

Table 172.135—Extent of Damage

Collision Penetration
Longitudinal extent0.495L 23 or 47.6 feet (( 13 )L 23 or 14.5m) whichever is shorter.
Transverse extent1B/5 or 37.74 feet (11.5m)2 whichever is shorter.
Vertical extentFrom the baseline upward without limit.
Grounding Penetration At the Forward End But Excluding Any Damage Aft of a Point 0.3L Aft of the Forward Perpendicular
Longitudinal extentL/10.
Transverse extentB/6 or 32.81 feet (10m) whichever is shorter.
Vertical extent from the baseline upwardB/15 or 19.7 feet (6m) whichever is shorter.
Grounding Penetration At Any Other Longitudinal Position
Longitudinal extentL/10 or 16.41 feet (5m) whichever is shorter.
Transverse extent16.41 feet (5m).
Vertical extent from the baseline upwardB/15 or 19.7 feet (6m) whichever is shorter.

1Damage applied inboard from the vessel's side at right angles to the centerline at the level of the summer load line assigned under Subchapter E of this chapter.

2B is measured amidships.

§172.140   Permeability of spaces.

(a) When doing the calculations required in §172.130, the permeability of a floodable space other than a machinery space must be as listed in Table 172.060(b).

(b) Calculations in which a machinery space is treated as a floodable space must be based on an assumed machinery space permeability of 0.85, unless the use of an assumed permeability of less than 0.85 is justified in detail.

(c) If a cargo tank would be penetrated under the assumed damage, the cargo tank must be assumed to lose all cargo and refill with salt water up to the level of the tankship's final equilibrium waterline.

§172.150   Survival conditions.

A tankship is presumed to survive assumed damage if it meets the following conditions in the final stage of flooding:

(a) Final waterline. The final waterline, in the final condition of sinkage, heel, and trim, must be below the lower edge of openings such as air pipes and openings closed by weathertight doors or hatch covers. The following types of openings may be submerged when the tankship is at the final waterline:

(1) Openings covered by watertight manhole covers or watertight flush scuttles.

(2) Small watertight cargo tank hatch covers.

(3) A Class 1 door in a watertight bulkhead within the superstructure.

(4) Remotely operated sliding watertight doors.

(5) Side scuttles of the non-opening type.

(b) Heel angle. (1) Except as described in paragraph (b)(2) of this section, the maximum angle of heel must not exceed 15 degrees (17 degrees if no part of the freeboard deck is immersed).

(2) The Commanding Officer, Marine Safety Center will consider on a case by case basis each vessel 492 feet (150 meters) or less in length having a final heel angle greater than 17 degrees but less than 25 degrees.

(c) Range of stability. Through an angle of 20 degrees beyond its position of equilibrium after flooding, a tankship must meet the following conditions:

(1) The righting arm curve must be positive.

(2) The maximum righting arm must be at least 3.95 inches (10 cm).

(3) Each submerged opening must be weathertight.

(d) Progressive flooding. Pipes, ducts or tunnels within the assumed extent of damage must be either—

(1) Equipped with arrangements such as stop check valves to prevent progressive flooding to other spaces with which they connect; or

(2) Assumed in the design calculations required by §172.130 to flood the spaces with which they connect.

(e) Buoyancy of superstructure. 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.

(f) Metacentric height. After flooding, the tankship's metacentric height must be at least 2 inches (50mm) when the ship is in the upright position.

(g) Equalization arrangements. Flooding equalization arrangements requiring mechanical operation such as valves or cross-flooding lines may not be assumed to reduce the angle of heel. Spaces joined by ducts of large cross sectional area are treated as common spaces.

(h) Intermediate stages of flooding. If an intermediate stage of flooding is more critical than the final stage, the tankship must be shown by design calculations to meet the requirements in this section in the intermediate stage.

[CGD 79-023, 48 FR 51040, Nov. 4, 1983, as amended by CGD 88-070, 53 FR 34537, Sept. 7, 1988]

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