Question

Water hammer is caused in steam carrying pipelines, because of

• A. Partial condensation of steam
• B. Vibration of pipeline
• C. High degree of super heat of steam
• D. Its exposure to torrential rain

Hint:

Water hammer in steam pipelines occurs due to partial condensation forming water slugs, which cause pressure surges when steam flow changes suddenly.

Answer 1

The Correct Option is A

Step 1: Understand water hammer in pipelines.
Water hammer is a pressure surge or shock wave in a pipeline caused by a sudden change in fluid velocity, often resulting in loud banging noises and potential damage to the pipeline. In steam-carrying pipelines, water hammer is a common issue due to the phase change properties of steam. Step 2: Analyze the cause of water hammer in steam pipelines.
Partial condensation of steam: When steam cools in a pipeline (e.g., due to heat loss to the surroundings), it partially condenses into water. The condensed water forms slugs that are carried by the high-velocity steam. If the steam flow suddenly stops (e.g., by closing a valve) or changes direction, the water slugs slam into pipe fittings, valves, or bends, causing a sudden pressure spike—water hammer. This is a well-known cause in steam systems.
Vibration of pipeline: While vibrations can cause noise, they are not the primary cause of water hammer, which is specifically related to fluid dynamics.
High degree of superheat of steam: Superheated steam (steam heated above its saturation temperature) is less likely to condense, reducing the risk of water hammer. High superheat is not a cause.
Exposure to torrential rain: External rain might cool the pipeline, potentially leading to condensation, but this is not the direct cause of water hammer in steam systems.
Step 3: Evaluate the options.
(1) Partial condensation of steam: Correct, as condensation forms water slugs that cause water hammer when steam flow changes suddenly. Correct.
(2) Vibration of pipeline: Incorrect, as vibrations are a consequence, not the cause of water hammer. Incorrect.
(3) High degree of superheat of steam: Incorrect, as superheated steam reduces condensation and thus reduces the likelihood of water hammer. Incorrect.
(4) Its exposure to torrential rain: Incorrect, as external rain is not a direct cause of water hammer in steam pipelines. Incorrect.
Step 4: Select the correct answer.
Water hammer in steam-carrying pipelines is caused by partial condensation of steam, matching option (1).