API MPMS Chapter 17.2

The determination of the quantity and quality of cargo on board marine tank vessels is frequently complex. It is necessary to accurately gauge, ascertain the temperature of, collect samples of, and calculate the amount of all materials contained in the vessel’s lines, cargo tanks, and slop tanks. Other spaces on the vessel may also contain cargo, such as ballast tanks, double bottoms, cofferdams, and numerous other nondesignated cargo spaces, all of which have to be checked, and any volumes contained in them calculated. Measurement accountability (quantity and quality) has to further take into account conditions such as, but not limited to, OBQ/ROB, line fullness, preloading tank inspection, closed measurement and sampling systems, and special procedures for chemical and gas cargoes. Reconciliation of the foregoing may be required if gains or losses exceed expected tolerances.

The detailed requirements for performing all of these actions are contained in numerous MPMS standards. This publication identifies the methods for performing these procedures on crude oils; petroleum products; chemical cargoes; LPG and LNG, normally carried on board marine tank vessels; and guides the user to the appropriate standard/guidance document within the MPMS suite of standards