I would like to ask everyone: is there a strength calculation for the nozzles included in the strength calculation sheet for pressure vessels? Can the strength calculation for nozzles that are connected to the vessel body be done using the formulas applicable to the vessel body itself?

This is indeed a crucial issue. I understand that you are asking whether the strength calculation for the junction between the take over and the cylinder can be directly based on the formulas for the cylinder itself. In reality, the area where the connection to the cylinder takes place is a region of local discontinuity, resulting in stress concentration. Using only the formulas for cylinders (such as the membrane stress formula) does not yield accurate results; it is generally necessary to carry out separate calculations for strengthening the area where the opening is present, or to conduct a local stress analysis using analytical design methods. To give a brief overview for reference: the cylinder formula is only applicable to areas under uniform stress far from structural discontinuities; the root of the nozzle clearly does not meet this condition, so it cannot be used directly. The conventional approach is to use the hole-strengthening calculation methods specified in GB/T 150.3 or ASME VIII-1, or to conduct a local strength check using the stress classification method (such as JB 4732); in addition, the nozzle itself must take into account additional loads such as axial forces and shear forces. If there are no specific calculations related to the splice in the calculation sheet, it is likely to be incomplete. It is recommended to include calculations for splice reinforcement or a local stress analysis. Of course, the specific parameters and standard requirements need to be determined based on your design conditions; it’s best to review the basis for the calculations again or consult experienced pressure vessel engineers.

The strength calculation document for pressure vessels includes the strength calculation of nozzles, but it is usually not presented as a separate section titled \"Nozzle Wall Thickness Calculation\"; instead, it is incorporated into the calculations for reinforcement due to openings and the verification of weld strength. In a proper strength calculation document for pressure vessels (such as one generated by SW6 or a manually prepared document), you won’t find a separate section titled “Nozzle Strength Calculation”; however, the calculated thickness of the nozzle (𝛿𝑡), the additional area (𝐴2), and the data related to weld strength verification can be found in the section on “Strengthening Calculations for Openings”. If the takeover fails to pass verification in any of the above steps, the design will be deemed unqualified.

If thinning occurs during use, how is it determined whether the requirements are met? Even if the strength meets the requirements, is it still necessary to calculate the area that needs to be reinforced?

It depends on the software you use for calculating strength. I’m not sure about SW, but PVdesktop’s calculation sheets include calculations for pipe joint strength; before the reinforcement calculations, there is a separate page dedicated to the strength calculations for the pipe joints