Answer :
Final answer:
Cracking may be suspected if the temperature swing exceeds about 150º F (A). Option A is correct.
Explanation:
Thermal fatigue occurs due to repetitive heating and cooling cycles in equipment. When equipment is frequently started up and shut down, it goes through these cycles. Every material has a particular resistance to temperature changes, and beyond a certain limit, repetitive swings can initiate cracks.
Let's understand this with a simple analogy. Imagine bending a paperclip back and forth. Initially, the paperclip is fine. But after several bends, it breaks. The paperclip is experiencing fatigue. Similarly, equipment experiences fatigue from temperature changes.
The temperature at which fatigue becomes concerning isn't an exact science but rather a rule of thumb derived from empirical evidence and material science studies. It's a guideline for engineers and operators to have an idea when they should be more concerned about thermal fatigue leading to cracking.
If the temperature swing is small, the chance of cracking is also smaller. But as the temperature swing increases, so does the susceptibility to thermal fatigue. Based on practical experience in many industrial environments, it's generally accepted that cracking might be suspected when temperature swings exceed about 150º F. Beyond this point, equipment should be closely monitored, and mitigation measures should be considered.
Thus correct option is A.
Learn more about Thermal fatigue
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