Evaluation of Tankers’ Longitudinal Strength

Lloyd’s Register (LR) reminds about the IMO requirements for longitudinal strength of oil tankers to be evaluated from July 1, 2002. The enhanced programme of inspection for oil tankers of 130m length or greater requires that, after such ships reach 10 years of age, their longitudinal strength must be evaluated at safety construction (SAFCON) renewal surveys. Full criteria for this is given in a new Annex 12 to IMO Resolution A.744(18).

Any renewal or reinforcement needed as part of this evaluation will require to be completed as part of the special survey. LR therefore strongly advises operators to ensure that thickness measurements are carried out in advance of the repair/docking period, so that the necessary work can be properly planned and prepared. Lloyd’s Register has developed a software calculation tool, TmCalc, which enables the evaluation of the longitudinal strength to be performed by the attending LR surveyor on receipt of the thickness measurement readings. Structural details (including original thickness readings) of the as-built transverse sections for those Lloyd’s Register classed ships which are affected by this requirement are being compiled in advance for use with TmCalc software.