Goal
To ensure the safe containment of cargo under all design and operating conditions
having regard to the nature of the cargo carried. This will include measures
to:
-
.1
provide strength to withstand defined loads;
-
.2
maintain the cargo in a liquid state;
-
.3
design for or protect the hull structure from low temperature exposure;
and
-
.4
prevent the ingress of water or air into the cargo containment
system.
4.1
Definitions
4.1.1
A cold spot is a part of the hull or thermal insulation surface where a
localized temperature decrease occurs with respect to the allowable minimum
temperature of the hull or of its adjacent hull structure, or to design capabilities
of cargo pressure/temperature control systems required in chapter 7.
4.1.2
Design vapour pressure "P0" is the maximum gauge pressure, at the
top of the tank, to be used in the design of the tank.
4.1.3
Design temperature for selection of materials is the minimum temperature at
which cargo may be loaded or transported in the cargo tanks.
LR 4.1-01 Where applicable, details of the arrangements proposed
to ensure that the tank or cargo temperature cannot be lowered below the minimum
design temperature are to be submitted for approval.
4.1.4
Independent tanks are self-supporting tanks. They do not form part of the
ship's hull and are not essential to the hull strength. There are three categories
of independent tank, which are referred to in 4.21, 4.22 and 4.23.
LR 4.1-02 Type A independent tanks are covered in 4.21, Type B
independent Tanks are covered in 4.22 and Type C independent tanks are covered in
4.23.
4.1.5
Membrane tanks are non-self-supporting tanks that consist of a thin liquid
and gastight layer (membrane) supported through insulation by the adjacent hull
structure. Membrane tanks are covered in 4.24.
LR 4.1-03 Membrane arrangements, other than those specified in
4.1.5, may be specially considered and are to be acceptable to the National
Administration.
4.1.6
Integral tanks are tanks that form a structural part of the hull and are
influenced in the same manner by the loads that stress the adjacent hull structure.
Integral tanks are covered in 4.25.
4.1.7
Semi-membrane tanks are non-self-supporting tanks in the loaded condition and
consist of a layer, parts of which are supported through insulation by the adjacent
hull structure. Semi-membrane tanks are covered in 4.26.
4.1.8 In addition to the definitions in 1.2, the
definitions given in this chapter shall apply throughout the Code.
4.2
Application
Unless otherwise specified in part E, the requirements of parts A to D
shall apply to all types of tanks, including those covered in part F.
LR 4.2-01 Details of the proposed design of containment systems
are to be submitted for consideration, and it is recommended this is done at as
early a stage as possible. For a description of LR’s system of approval, refer to
the ShipRight Procedure Additional Design Procedures, Approval Scheme for Gas
Ship Containment Systems.