This International Standard specifies a method for the internal measurement of membrane tanks used in ships for the transport of refrigerated light hydrocarbon fluids. In addition to the actual process of measurement, it sets out the calculation procedures for compiling the tank capacity table and correction tables to be used for the computation of cargo quantities. This International Standard, with some modification, can also be applicable to the calibration of independent prismatic tanks.For the manual measurement of membrane tanks, the procedures of this International Standard utilize the scaffolding used for the installation of the membranes to support the measuring equipment but, for the internal electro-optical distance-ranging (EODR) method, other safe means of access to the required measuring positions are intended to be used.