[Code of Federal Regulations]
[Title 46, Volume 1]
[Revised as of January 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 46CFR38.05-4]

[Page 497]
 
                           TITLE 46--SHIPPING
 
         CHAPTER I--COAST GUARD, DEPARTMENT OF HOMELAND SECURITY
 
PART 38_LIQUEFIED FLAMMABLE GASES--Table of Contents
 
                  Subpart 38.05_Design and Installation
 
Sec. 38.05-4  Design and construction of nonpressure vessel type cargo

tanks--TB/ALL.

    (a) The requirements in this section anticipate a cargo containment 
system consisting of a primary tank which is structurally self-
supporting and, where required, a secondary barrier. Other vessel or 
cargo tank configurations, such as membrane type liners externally 
supported, will be considered upon submission of substantiating data, 
and based upon such additional tests as the Commandant may direct.
    (b) A secondary barrier is an arrangement or structure designed to 
contain the cargo temporarily if leakage develops in the primary 
container. A secondary barrier shall be provided where leakage from the 
primary container may cause lowering of the temperature of the ship's 
structure to an unsafe level. The secondary barrier shall be constructed 
of material suitable to contain the cargo at the service temperature.
    (c) The design of the cargo containment systems shall be such that 
under normal service conditions, or upon failure of the primary tank, 
the hull structure shall not be cooled down to a temperature which is 
unsafe for the materials involved. Structural members not suitable for 
the service temperatures of the cargo shall be protected by a secondary 
barrier consisting of suitable structural containment together with 
necessary associated insulation. Heat transmission studies and tests may 
be required to demonstrate that the arrangement is feasible and that the 
final material temperatures are acceptable.
    (d) The design and construction of the cargo tanks shall be at least 
equivalent to the standards established by the American Bureau of 
Shipping or other recognized classification society. For special tanks, 
or designs not contemplated by standards of the classification society, 
a detailed analysis of the entire tank, or designated parts thereof, 
shall be made and submitted to the Commandant for approval.
    (e) The cargo tank shall be designed for a head of cargo at least 
equal to the highest level the liquid cargo may attain plus the maximum 
venting pressure. In no case shall a head of cargo less than 4 feet 
above the cargo hatch or expansion trunk be used.
    (f) The design shall investigate the thermal stresses induced in the 
cargo tank during loading. Where necessary, devices for spray loading or 
other methods of precooling or cooling during loading shall be included 
in the design.
    (g) All weld intersections or crossings in joints of primary tank 
shells shall be radiographed for a distance of 10 thicknesses from the 
intersection. All other welding in the primary tank and in the secondary 
barrier shall be spot radiographed in accordance with the requirements 
of part 54 of subchapter F (Marine Engineering) of this chapter.

[CGFR 66-33, 31 FR 15269, Dec. 6, 1966, as amended by CGFR 68-82, 33 FR 
18807, Dec. 18, 1968]