LNG tank 'fender' takes vessel design beyond B/5
IMO regulations require a minimum safe distance between LNG tanks and the ship’s shell, which further restricts the naval architect’s design space. RINA article describes the idea of LNG tank placement which provides more design freedom without compromising safety, or even improving safety. Safety considerations IMO’s draft international code of safety for ships using gases or other low-flashpoint fuels (IGF Code) stipulates a minimum safe distance between a storage fuel tank and the ship’s shell of 1/5th of the ship’s beam, B. At other levels the distance should never be less than 760mm (IGF 2014). This requirement has been taken from existing IMO regulations for sea going gas tankers (IGC 2014), which has proven satisfactory over the past 50 years. In fact the B/5 requirement has been copied from the early SOLAS regulations on damage stability which is inspired by damage statistics recorded between 1948 and 1966. It shows that, given a collision, the probability of the damage penetration not exceeding 1/5th of the ship’s beam equals 55%. It also shows that in 45% of the collision cases, this distance is exceeded. Obviously these statistics are outdated; ship structures have changed significantly since the late sixties of the previous ...
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