Opening reinforcement: a fabricator provides a reinforcing pad around every nozzle equal in thickness to the shell and extending to twice the opening diameter. If code area replacement is the governing criterion, would this be safe regardless of vessel shape?

Introduction / Context:
Nozzle openings in pressure vessels remove load-bearing metal from the shell. Design codes require that the lost membrane area be compensated by reinforcement (nozzle neck, pad, shell excess thickness). While the exact stress distribution depends on shell shape, the fundamental “area replacement” concept can be satisfied with generous, geometry-independent pads.

Given Data / Assumptions:

• Reinforcing pad thickness equal to shell thickness.
• Pad radial extent up to twice the opening diameter all around.
• Area-replacement method is the governing requirement; local loadings and external piping loads are not limiting.

Concept / Approach:
Area-replacement sums available reinforcement in a prescribed zone around the opening. If the provided pad material is ample compared to the required compensation, the opening meets the area rule independent of whether the shell is spherical or cylindrical. Secondary effects (discontinuity stresses, local bending) can still require checks, but the area criterion is met.

Step-by-Step Solution:

Verification / Alternative check:
Sample calculations for both cylindrical and spherical shells show large positive margins when such a generous pad is used.

Why Other Options Are Wrong:

• Restricting validity to a specific shell orientation (vertical/horizontal) or to spherical only is unnecessary if the area rule is satisfied.

Common Pitfalls:
Ignoring external piping loads, which may require reinforcement beyond simple area replacement; neglecting pad-to-shell weld details and telltale holes; overlooking PWHT and NDE requirements.

Final Answer:
Irrespective of the shape of the vessel