Section 18 Inert gas systems

18.1.1 Inert gas systems installed on board units intended for the storage of oil in bulk storage tanks are to be surveyed annually in accordance with the requirements of 2.6. A Special Survey of the inert gas system, in accordance with the requirements of 18.2, is to be held at intervals not exceeding five years.

18.2.1 At each Special Survey of the inert gas system, the inert gas generator, scrubber and blower are to be opened out as considered necessary and examined. Gas distribution lines and shut-off valves, including soot blower interlocking devices, as well as interlocking features and positive isolation for tank isolation are to be examined as considered necessary. The deck seal and non-return valve are to be examined. Cooling water systems including the effluent piping and overboard discharge from the scrubbers are to be examined. All automatic shut-down devices and alarms are to be tested. The complete installation is to be tested under working conditions on completion of survey.

18.2.2 When, at the request of an Owner, it has been agreed by the Classification Committee that the Complete Survey of the inert gas systems may be carried out on the Continuous Survey basis, the various items of machinery are to be opened for survey in rotation, so far as practicable, to ensure that the interval between consecutive examinations of each item will not exceed five years. In general, approximately one fifth of the machinery is to be examined each year.

18.2.3 If any examination during Continuous Survey reveals defects, further parts are to be opened up and examined as considered necessary by the Surveyor, and the defects are to be made good to his satisfaction.

18.2.4  See Pt 1, Ch 3, 21.3 Annual Surveys − General Requirements for Fuel Systems andPt 1, Ch 3, 21.8 Complete Surveys − General requirements for inert gas systems on units with natural gas fuel installations.