Stress analysis and design of a large propylene spherical tank based on ASME VIII-2

Adopting the ASME VIII-2 standard analysis and design method, ANSYS finite element software was used to analyze and calculate a 6000m³ propane spherical tank, which is critical for storing propane as a raw material for hydrogen production in the hydrogen energy sector. The study discusses the establishment of the finite element model of the spherical tank, structural optimization of the connection between the support pillar and the spherical shell, support pillar stability, local failure, and other key issues. Secondary development of the ANSYS software was conducted, with a subroutine written to calculate the algebraic sum of the three principal stresses, and the calculation results were verified. The study indicates that the maximum stress occurs at the connection between the support pillar cap and the spherical shell; reducing the thickness of the support pillar cap can effectively reduce local stress values. The weld seam on the outer side of the nozzle-to-spherical shell connection is the critical area for local failure; increasing the weld leg height or using an integral forging with a large fillet can significantly reduce the risk of failure. Stability calculations of the spherical tank support structure under hydrostatic test loads showed that the first yield point occurs at the connection between the upper support pillar and the spherical shell. It is proposed that the stability of the support pillar should not be calculated solely based on steel structure standards but should also consider the impact of local buckling. This research is significant for the hydrogen energy industry, which plays a pivotal role in space engineering, as propane storage tanks are essential for storing the raw materials used in hydrogen production.