Fluid Catalytic Cracking (FCC) Unit is a large-pressure vessel that converts heavy crude oil, which cannot be distilled, into light crude oil. With the growing interest in renewable energy sources due to environmental regulations, various studies investigating FCC Units are ongoing. The catalytic reactor in FCC Unit is a large structure that generates prolonged high pressure, leading to changes in the properties of the material during operation. Therefore, stress analysis must be conducted based on the application of the actual mechanical properties. In cylindrical thin structures such as the FCC reactor, a tensile test is difficult to perform, warranting the need for Shear Punch (SP) test that uses a small specimen. The properties were utilized in finite element analysis. To determine the boundary and load conditions needed for stress analysis, the operational conditions of the reactor and the conditions for internal pressure of ASME Code regulation were used to evaluate the stress.