Section 1 General

1.1.1  Cold spot. A cold spot is a part of the hull or thermal insulation surface where a localised temperature decrease occurs under loaded condition 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 Pt 11, Ch 7 Cargo Pressure/Temperature Control .

1.1.2  Design vapour pressure. The design vapour pressure ‘P _o’ is the maximum gauge pressure, at the top of the tank, to be used in the design of the tank.

1.1.3 Cargo design temperature. The design temperature for selection of materials is the minimum temperature at which cargo may be loaded or stored in the cargo tanks.

1.1.4  Independent tanks are self-supporting; they do not form part of the hull of the ship unit and are not essential to the hull strength. There are three categories of independent tank, which are referred to in Pt 11, Ch 4, 6.2 Type B independent tanks and Pt 11, Ch 4, 6.3 Type C independent tanks.

1.1.5  Membrane tanks are non-self-supporting tanks that consist of a thin liquid and gas tight layer (membrane) supported through insulation by the adjacent hull structure. Membrane tanks are covered in Pt 11, Ch 4, 6.4 Membrane tanks.

1.1.6  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 Pt 11, Ch 4, 6.5 Integral tanks.

1.1.7  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 Pt 11, Ch 4, 6.6 Semi-membrane tanks.

1.1.8 In addition to the definitions in Pt 11, Ch 1, 1.3 Definitions, the definitions given in this Chapter shall apply throughout this Part.

1.1.9  Recovery Duration (RD). When a secondary barrier, or a partial secondary barrier, is required an RD is defined as the time (in days) necessary to make the ship unit safe, secure and ready for repair after a leak through the primary barrier is detected.

In the calculation of the RD, due account shall be taken of liquid evaporation, rate of leakage, access to external facilities such as shuttle tankers, pumping capacity and other relevant factors such as operational situations, human factors, delays due to weather conditions.

The required RD and the associated safety factor shall be advised to LR at the commencement of the project.

1.2.1 Unless otherwise specified in Pt 11, Ch 4, 6 Tank types, the requirements of Pt 11, Ch 4, 2 Cargo containment to Pt 11, Ch 4, 5 Materials and construction shall apply to all types of tanks, including those covered in Pt 11, Ch 4, 7 Guidance.