The Oil Industry has a continuous interest in reducing operating costs. Some significant efforts have been made and notable improvements of Inspection, Maintenance, Repair (IMR) activities have been achieved in the last years. Offshore engineers continue to work in developing innovative approaches with the finality of achieving more and more cost effective solutions, without reducing the safety level of the facilities. This paper summaries the reassessment study that ENI/AGIP decided to develop in order to define new criteria for underwater inspection planning and produce new specifications concerning all the Italian offshore platforms. The engineering work was performed by Tecnomare involving the global review of original inspection schedule and covering the remaining years of life of the installations. During the first service period the offshore platforms were subjected to periodic underwater inspections but no significant failures were detected. In order to eliminate unnecessary tests a new approach has been followed based on the recent monitored environment data and the reliability re-assessment analysis of the offshore structures in operating conditions. The target is the reduction of the critical elements to be inspected and survey frequency, without compromising the overall structural safety. The Class of Risk of each platform has been introduced on the basis of the following parameters:
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Duration of the manned period of the platform
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Environmental effects of the platform failure
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Economic asset of the platform
Specific reliability target values have been selected for the critical components as function of their structural importance and platform class of risk. In addition the introduction of FMD examinations substitutes MPI on less important components and assures the periodic random check of the soundness of the platform. The collected data, coming from offshore recordings, has allowed to increase the fatigue life of several platforms. The replanning of the underwater inspections is reported and relevant cost saving is outlined.
