[Code of Federal Regulations]
[Title 46, Volume 7]
[Revised as of October 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR172.150]

[Page 152-153]
 
                           TITLE 46--SHIPPING
 
   CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED)
 
PART 172_SPECIAL RULES PERTAINING TO BULK CARGOES--Table of Contents
 
 Subpart F_Special Rules Pertaining to a Ship That Carries a Hazardous 
           Liquid Regulated Under Subchapter O of This Chapter
 
Sec. 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.

[[Page 153]]

    (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 Sec. 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]