A Life Extension Program is a predictive analytical system coupled with a pro-active approach to extend a vessel service life and maintain structural integrity
Predictive Analytical System
The components of a Life Extension Program as inspection, repair and maintenance contribute to build up a predictive analytical system coupled with a pro-active approach. This pro-active approach will necessary search and find the necessary remedies for different structutral issues which may arise with time.
The pro-active approach consists of finding the remedies and apply these to prevent and avoid any upcoming structural issues. The shape of the bracket on the picture has been improved and subsequently ultrasonic peening has been used to further enhance the fatigue resistance of the areas showing high stresses.
Various fatigue life probabilities
Calculating fatigue lives to 2.5% probability, 20% and 50%, will allow an appreciation of the seriousness of each fatigue sensitive location in the hull; allowing a higher probability or higher risk for a crack to occur would, at least theoretically, allow longer life span without repair or post weld treatment of any type. For example, calculating a fatigue life to 50% probability for longitudinal connections in the way of web frames indicates that roughly half of the connections will show fatigue cracks for that specific life. Furthermore, this analysis will make it possible to calculate the potential repair costs throughout the remaining service life of the installation.
Causes and engineering solutions to structural issues
A greater understanding of the cause to any upcoming structural issue would allow for the identification of potential solutions . The possible solutions should then need to be evaluated in view of the effectiveness in solving the issue, practicality, safety and cost effectiveness. One of the engineering solutions used to prevent premature fatigue cracking is ultrasonic peening treatment.