Double hulled tankers have a high level of structural complexity, the number of structural intersections is almost twice that of an equivalent size single hull ship.
Leakages of cargo into the ballast spaces from cracks in the inner hull structure were seen as a major risk.
Fatigue and corrosion were highlighted as potential causes of such failures.
In the following figure the common areas of stress concentration and fatigue failure are shown.
These include connections of inner hull plating at the upper and lower intersections of the sloping hopper, connections at the toes of brackets and stringers and the intersections of secondary longitudinal stiffeners with transverse members.
