The Joint Tanker Project (JTP) team of Lloyd’s Register, ABS and DNV has delivered draft common Rules for oil tankers
, equal to or greater than 150 metres in length, to their technical committees, the wider industry and the International Association of Classification Societies
for review and comment. We have provided the knowledge and the processes to enable shipowners and shipbuilders to implement the new Rules.
The objectives of JTP have been to improve the robustness and durability of oil tankers and to eliminate different approaches to scantling requirements. The new Rules are fundamentally different from the current Rule sets in several ways:
· transparency: there is now an explicit relationship between the applied loads and the structural capacity to withstand them to a satisfactory factor of safety
· net scantlings: the approach is based upon net thickness plus a corrosion margin. The net thickness is the material required to withstand the loads applied. The corrosion margin is the material required to withstand an average level of corrosion over the ship’s life
· explicit renewal thickness: a value, in millimetres, at which renewal must take place, is derived at the design stage
· direct calculations harmonised: an agreed common approach is adopted for each of the different necessary checks such as fatigue, buckling, finite element assessment and sloshing
· loads: there have been significant changes to the basis and application of the static and dynamic loads that are applied to the hull structure for deriving scantlings by both prescriptive and direct methods.
The schedule for the new Rules is as follows:
· end of June 2004 – new Rules distributed to the technical committees of the three societies and the rest of the industry for consultation
· January 1, 2005 – new definitive Rules published
· July 1, 2005 – new Rules become effective, superseding the current Rules.