Probabilistic inspection planning of the Asgard A FPSO hull structure withrespect to fatigue

Probabilistic methods has been used to develop a basis for an in-service in spection program for the Asgard A FPSO hull structure with respect to fatig ue cracks;Asgard A is a floating production unit constructed for Statoil an d was installed on the Asgard Field during the winter 1999. Hot spot areas showing the shortest calculated fatigue lives have been selected for probab ilistic analyses. This implies areas at doubling plates and transverse stif feners in the deck structure and the connections between the side longitudi nals and the transverse frames. In FPSOs, there are a number of derails wit h similar geometry that also are fabricated in the same way. Some of the de rails like those in the deck structure are also subjected to the same magni tude of loading. Consequently, there will be correlation in fatigue life wh en several components are considered at the same time. The effect of this c orrelation has been investigated for components that have a welded surface and components that are ground. A number of analyses have been performed to investigate the effect of this correlation on required amount of in-servic e inspection. And it is shown how results from these analyses are transferr ed into an in-service inspection program for the Asgard A FPSO. [S0892-7219 (00)00302-2].