✍️ In this project, we have optimized a pressure vessel to fulfil the requirements for earthquake safety as defined in EN 1998-1 ISO standard as well as in the pressure vessel codes.
The FEM analysis results show that the original design needs to be optimized, the legs of the pressure vessel that are in contact with foundation plates do not provide enough strength to meet displacement criteria for earthquake accelerations.
The optimized model presents a good solution for the weak parts of the original design and the pressure vessel can meet defined criteria based on EN 1998-1 and AD 2000 / EN 13445 with a good factor of safety.
FEM Analysis was conducted based on the 3D-CAD (Inventor) model (provided by the customer), to detect weak points of the structure under earthquake, pressure and temperature loads. Furthermore, static deformation has been considered.
For the evaluation of the earthquake safety of pressure vessel plants site, a detailed analysis should be done, where already a detailed calculation of the steel structure was made and maximum displacement and stiffness of this structure were calculated.
The FE model was conducted in ANSYS. Claddings on the flanges were not included in the model as required by EN13445-3. The contact between the flanges was modelled only in the respecting contact area. Ignorable and irrelevant features in the 3D model were omitted for simplicity of the FE model.
The bonded contacts, which were used for welded parts, were defined using the weld thickness. All frictional contacts were defined with a friction coefficient of 0.15 as a good estimation for the desired safety factor.
For most of the flanges, the bolt holes were removed and instead the resulting pressure force, which would be introduced with the bolts, was applied to a ring surface area resembling the bolt holes.
The mass of relevant attached parts was introduced as a point mass on remote points, the pressure vessel’s filling weight was considered as the distributed mass on the pressure vessel shell, as defined in EN 1998-4.
For more information about this project please contact us directly.