The cost of inspections of marine structures such as jackets, semi-submersibles and floating production vessels can put a strain on already challenged operational budgets -driving the need to develop inspection programs only addressing critical areas.
So DNV GL has now launched a recommended practice (DNVGL-RP-C210) providing the first international guidance on how to establish a sound basis for in-service inspection planning for fatigue cracks in marine structures.
The guidance will save operational costs by using a risk-based approach to identify the ‘hot spots’ requiring inspection. DNVGL-RP-C210 is based on the findings of a DNV GL led joint industry project completed in 2013.
Kjell Eriksson, Regional Manager for DNV GL Oil & Gas in Norway, said: “What we are commonly experiencing, is the use of inconsistent inspection planning methodologies, which can result in costly inspections at non-critial areas, or worse, no inspection at critical areas.
“The cost reduction is obtained by reducing the overall inspection and maintenance scope, still ensuring continued cost-efficient safe operation of the asset. This is done by using risk based methods in identifying the critical areas, so-called ‘hot spots’, that needs to be inspected and non-critical areas that do not need further assessment.
“The criticality of fatigue cracks can vary, which combined with costly inspections programs drives the importance of developing accurate methods for identification of fatigue critical areas,”
“The use of risk based inspection planning for identification of critical aras for inspections will result in reduced inspection program and thereby a corresponding significant reduction in the inspection and operational costs.”
In-service inspection for fatigue is carried out to assure that possible cracks in the structure do not exceed a critical level. The outcome of in-service inspections can then be used to update the estimated fatigue reliability of the structure.