Boiler basics: identify the configuration Statement: In a fire-tube (smoke-tube) boiler, the water is contained inside the tubes while the flames and hot gases flow outside the tubes.

Introduction / Context:
The classification of boilers into fire-tube (smoke-tube) and water-tube types is fundamental in thermal engineering. Many design, safety, and performance features hinge on which medium—hot gas or water/steam—occupies the tubes. This question tests your ability to recall the correct configuration and its implications for pressure levels, response, and maintenance.

Given Data / Assumptions:

• Conventional stationary boilers used for steam generation in power and process applications.
• Comparison between fire-tube and water-tube constructs only.
• No superheater, reheater, or economizer complications are required to answer.

Concept / Approach:
In a fire-tube boiler, hot combustion gases pass through tubes that run inside a water-filled shell. Heat transfers through the tube walls to the surrounding water, generating steam in the shell. In a water-tube boiler, the arrangement is reversed: water flows inside the tubes, and hot gases wash over the outside of the tubes. This inversion drives major differences in allowable pressure and response time.

Step-by-Step Solution:
Identify the claim: “water is contained inside the tubes” for a fire-tube unit.Recall: fire-tube → hot gases in tubes; water/steam around tubes in the shell.Therefore, the statement reverses the true arrangement.Conclusion: the statement is false.

Verification / Alternative check:
Classic examples include the Cochran and Lancashire boilers (fire-tube), where multiple smoke tubes carry flue gases through a water-filled shell. Water-tube examples (Babcock & Wilcox) clearly show water/steam inside tubes with external hot gas flow.

Why Other Options Are Wrong:
“True only for water-tube boilers” mislabels the class; water inside tubes defines water-tube, not fire-tube. Superheaters and once-through boilers are different subsystems or modern designs and do not make the original statement correct for a fire-tube boiler.

Common Pitfalls:
Memorizing names without associating them to geometry; assuming “tube” always contains water; conflating shell-and-tube heat exchanger intuition with boiler construction.

Final Answer:
False