The inplace analyses are intended to assess the adequacy of units for all anticipated loading conditions once the unit is in place for its expected functions and operations. Offshore units can experience a combination of complex loadings from dynamic offshore environment in operating and survival conditions including wind, wave, currents, seismic activities, service loads, ship impact, accidental loads etc. and all applicable conditions are considered in the inplace analyses.
The preservice analyses are intended to assess the adequacy of units for all anticipated loading conditions prior the unit is in place for its expected function and operations. Various pre-service conditions we analyze includes Lifting, Land transportation, Loadout , Ballasting, Sea-fastening, Sea-transportation, Launching, Upending, Float-over, Mating, On-bottom Stability, Installation, Pile Drivability etc. based on the type of unit and applicability.
An offshore installation is exposed throughout its life to environmental loading which causes cyclic stress variations in its structural members resulting in the possibility of fatigue cracking in these members. Fatigue analysis is carried out as part of new designs for finding out design life and also in life extension projects to find out the expended life and remaining life. Fatigue analysis is typically carried out for various types of structures like offshore jackets, hulls of floating units, crane foundations, foundations for vibrating equipment, mooring systems etc. susceptible to cyclic loadings under wave actions or operating cyclic loads.