A pressure vessel is said to be a thin shell when the ratio of wall thickness of the vessel to its diameter is __________ 110.

Answer: Option B

The correct answer is Option B: Less than

Here's why:

In mechanical engineering, specifically in the study of pressure vessels, we categorize them as either "thin shells" or "thick shells" based on the ratio of their wall thickness (t) to their inner diameter (D).

A pressure vessel is considered a thin shell when the wall thickness is relatively small compared to its diameter. This allows us to make certain simplifying assumptions in our calculations of stress and strain.

The generally accepted criterion is:

If t/D < 1/10, then the vessel is considered a thin shell. This means the wall thickness (t) must be less than one-tenth of the diameter (D). If the wall thickness is too large compared to the diameter (t/D >= 1/10), it's considered a thick shell, and different, more complex formulas are needed.