Need:

Pythagoras Engineering was contracted by Worldwide Oilfield Machine USA (WOM) to analyze the subsea wellhead systems. The objective of this presentation is to provide an insight of technical requirements and the numerical calculations performed using FEA techniques to evaluate the structural capacity of the casing hangers. ANSYS mechanical was used for the FEA simulation.

Scope:

Objective of this FEA is to evaluate the external and internal pressure capacity along with the string loads for the first and second position casing hangers as per API 17 D second edition and API 6A 21st Edition.

Methodology:

The FE model was generated using ANSYS mechanical. By taking advantage of the symmetry, half symmetry model was considered for the analysis. The advanced meshing technology of ANSYS was extremely robust in meshing the complex geometry of casing hanger and the jewelry components with higher order SOLID hex elements. Frictional contact and constrain equations were used at the interface between the mating surfaces. As per API 6X Elastic-plastic calculations, bi-linear kinematic  material model was used to account for the material non-linear behavior. The Internal and external pressure loads along with the string loads are applied on the casing hangers with incremental steps to evaluate the collapse loads. The powerful solving technology and High performance computing offered by ANSYS helped in reducing the runtime and achieve convergence in solving this highly non[1]linear problem effectively. Due to this reduction in runtime, the casing was evaluated for multiple cyclic loading to calculated the damage, fatigue, ratcheting/shakedown as per ASME and the casing hangers design is acceptable and meets the industrial standard requirements

Results Outcome:

FEA results are used to evaluate the casing hangers design as per the API17D, API6X and ASME VIII div 3 industrial codes and found to be acceptable