This paper consists of two parts. The first part describes all the phases that the fixed platform pedestal goes through, from the design and construction on land, to its installation on the offshore site and the removal of buoyancy tanks. Special emphasis was placed on the final phase, i.e. the removal of the buoyancy tank. The structure mentioned in this paper is used when installing fixed platforms at depths up to 400 meters. In the second part, a dynamic analysis in the time domain for the offshore operation of lifting the buoyancy tank from the water was performed. Based on the results of the dynamic analysis, the boundary weather conditions under which the operation may be performed were selected. The dynamic analysis was performed using the computer program MOSES. The thesis itself was prepared in collaboration with the NAVAS department, SAIPEM S.p.A. River. Based on the results of the dynamic analysis, it can be concluded that, when lifting the buoyancy tank, the dominant loads that occur are ones due to the interaction of structure and waves. The movement of the DB had less of an impact on the forces occurring in the lifting equipment. With the assumption that the DB anchoring system compensates for second-order movements.