Is it necessary to consider internal pressure when using finite element analysis to check the strength of pressure vessels?

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I would like to use the finite element method to verify the strength of the mixer inside the red box, mainly because two relatively large holes have been made (the hole ratio at the inclined tube area is >0.5); performing reinforcement calculations according to GB150 does not give me enough confidence. Because this is part of the entire piping network, and the whole network has already been subjected to stress analysis using AUTO Pipe (a software similar to CII); the forces and moments at points A, B, C, and D are taken from the results of those analyses as external loads. I have the following questions now; I would appreciate it if you could give me some advice: 1. My colleague did the calculations. According to him, in ANSYS the temperature and allowable stress values are not automatically linked to each other. Since there are fixed supports arranged around the middle of the mixer, entering temperature parameters would definitely result in thermal expansion stresses that exceed the allowable limits at those fixed supports. Therefore, he carried out his calculations assuming normal temperature conditions, and used the allowable stress values corresponding to the actual operating temperature. I’m not sure whether this approach is correct 2. Have the node forces and moment results calculated by AUTO Pipe already taken into account the effect of internal pressure? When using ANSYS for calculations, in addition to the values computed by AUTO Pipe, is it necessary to apply an axial tensile force resulting from the operating internal pressure at points C and D as well? 3. Based on the current calculation results, although the wall thicknesses of both the main pipe and the branch pipes are much larger than those calculated using the formula for pipe wall thicknesses (with the branch pipe wall thickness/main pipe wall thickness ratio being 0.4), and reinforcement through opening has been carried out in accordance with GB150 standards, the stress at the sharp corners of the inclined pipes still exceeds the allowable limits. Even if the inclined pipes are modified to have 90-degree vertical openings, the requirements for safety still cannot be met according to the evaluation criteria specified in JB4732. So is there anything wrong with the calculation method used earlier? If not, what measures should be taken next to make improvements – should the wall thickness of the branch pipes be increased further, or should the radius of the fillet at the openings be increased? Or increase the main diameter to reduce the opening ratio?