The words “to prevent the tank from becoming liquid full" contained in
paragraphs 8.3.1 and 15.1.4.2 have the following meaning: At no time during the
loading, transport or unloading of the cargo including fire conditions will the tank be
more than 98% liquid full, except as permitted by paragraph 15.1.3. These requirements, along with those of paragraph 8.2.17, are intended to ensure that the pressure relief valves
remain in the vapour phase, since their design and capacity are based on such a
condition.