NYK LNG Shipmanagement Ltd. (head office: Chiyoda-ku, Tokyo; president: Akio Ono), which is an NYK Group company, and SEA Systems (head office: Sasebo City, Nagasaki Prefecture; president: Akira Matsuo) have jointly developed “LNG Cargo Shift Calculation for Emergency Departure,” for membrane-type1 LNG vessels.
Membrane LNG vessel tanks are potentially liable to damage caused by sloshing,2 depending on the amount of liquefied natural gas in the tanks, when a rapid departure is required due to such emergencies as strong winds, earthquakes, or the outbreak of fire during the loading and unloading of cargos. In response to the sharp increase in membrane LNG vessels over recent years, the two companies cooperated in developing software that will help prevent damage to tanks during such emergencies.
The software instantly ascertains whether there is a risk that the tanks may be damaged due to sloshing, based on the liquid level of a vessel's tanks during cargo operation. If a risk is detected, the software displays a safe loading pattern. Additionally, to ensure a sound loading pattern, the software immediately calculates and displays the time required for the shifting of LNG among tanks. Moreover, calculation time during emergencies is shorted because of the easy detection of safe loading patterns and the quick calculation of the time required in case of emergency, and secondary accidents that could be caused by a miscalculation or error are thus prevented.
As of June 2009, the software will be installed in 12 membrane LNG vessels managed by NYK LNG Shipmanagement Ltd. and its sister company, NYK LNG Shipmanagement (UK) Ltd.
The NYK Group is committed to pursuing safe operations of its vessels through the introduction of innovative technologies.
1There are two general types of LNG vessels: membrane-type and moss-type. Membrane LNG vessels have cubic tanks with inner walls lined with special alloys, such as stainless-steel and "invar steel." Moss LNG vessels have spherical tanks made of aluminum alloy. Membrane LNG vessels have the risk of damage to the inner walls of the tanks when LNG in the tanks is sloshed around violently due to movement by the vessel’s hull.
2Sloshing refers to the intense movement of LNG in the tank due to the motion of the ship’s hull.