Minimum wall thickness of metallic storage vessels depends on what variables? Choose the most complete statement.

Introduction / Context:
Determining wall thickness for pressure-containing vessels and storage tanks requires balancing strength, geometry, and service conditions. Codes provide formulas that include material properties, pressure, diameter, and joint efficiency, plus allowances.

Given Data / Assumptions:

• Metallic cylindrical/spherical vessels under internal pressure.
• Design per recognized codes with joint efficiency factors.
• Temperature limits affect allowable stresses.

Concept / Approach:
For thin shells, fundamental hoop-stress relationships lead to thickness proportional to pressure * radius divided by allowable stress, modified by joint efficiency. Allowable stress derives from material yield/ultimate strength and design temperature. Geometry (diameter) sets radius, directly impacting required thickness.

Step-by-Step Solution:
Material property/temperature → allowable stress S(T).Pressure P and diameter D → hoop stress ~ P * D / (2 t).Joint efficiency E reduces effective strength; thickness scales by 1/E.Thus, thickness = f(P, D, S(T), E), confirming all listed variables matter.

Verification / Alternative check:
Design equations from pressure vessel codes explicitly include P, D (or radius), S (function of material and temperature), and weld efficiency; corrosion and mill tolerances add further allowances.

Why Other Options Are Wrong:
Any single-variable choice ignores interacting effects in code formulas and real design.

Common Pitfalls:
Neglecting temperature derating; forgetting joint efficiency for welded seams; omitting corrosion allowance and tolerances.

Final Answer:
All (a), (b) and (c)