Steam generation and pressure vessels — evaluate the statement: “A thick pressure vessel is always used for generating steam because it can withstand high pressures.”

Introduction:
This item checks conceptual understanding of thin vs thick pressure vessel design and the realities of steam generation equipment (boilers and drums). Not every steam generator uses a thick shell; selection depends on diameter, pressure level, and practical fabrication/heat-transfer constraints.

Given Data / Assumptions:

• Comparing “thick” vs “thin” shell criteria.
• Typical steam drums and boilers operate with diameters where t/D is small.
• Design must satisfy stress limits and heat-transfer needs.

Concept / Approach:
Classification often uses t/D thresholds (e.g., thin when t/D is small). Many boiler drums and shells are analyzed with thin-shell formulas because their walls, though substantial in mm, are still “thin” relative to large diameters. Thick cylinders are favored when high pressure and small diameter push t/D into the “thick” regime and stress varies significantly through the wall thickness.

Step-by-Step Solution:

Verification / Alternative check:
Typical water-tube boilers employ drums with large diameters and wall thicknesses small relative to diameter, validating thin-shell assumptions at code-checked thicknesses.

Why Other Options Are Wrong:

• True variants: Overgeneralize; thickness choice is not universal for steam generation.
• “Thin shells always regardless of pressure”: Also incorrect; very high pressures or small diameters may require thick-cylinder analysis.

Common Pitfalls:
Equating “withstand high pressure” with “must be thick.” Thickness is set by code equations, diameter, material strength, corrosion allowance, and fabrication—sometimes thin-shell theory remains valid.

Final Answer: