Which of the following vessels is most likely to be affected by thermal fatigue?

Which of the following vessels is most likely to be affected by thermal fatigue?

• A. Coke drum
• B. Distillation column
• C. Knockout drum
• D. Overhead accumulator

Answer: (A)

Thermal fatigue is a type of material degradation that occurs due to cyclical thermal stresses resulting from temperature fluctuations. In the context of pressure vessels, certain types of vessels are more susceptible to this phenomenon due to their operating conditions. Coke drums are specifically designed to handle the thermal cycling involved in the coking process, where feedstock is subjected to extreme temperatures during the conversion to petroleum coke. This process involves rapid heating and cooling cycles, which can induce significant thermal stresses in the material. As these cycles occur, especially in the transition phases between hot and cold, the material can expand and contract, leading to fatigue failures over time. Other vessels, such as distillation columns and knockout drums, experience more stable temperature conditions during their operation. Distillation columns maintain a more constant temperature gradient as they separate components based on boiling points, and knockout drums are generally designed to handle liquid and gas separation without drastic thermal changes. Overhead accumulators, while they may experience some temperature variations, are also less prone to the severe thermal cycling characteristics associated with coke drums. Therefore, the nature of the coke drum's operational cycle makes it the vessel most likely to be affected by thermal fatigue.

Thermal fatigue is a type of material degradation that occurs due to cyclical thermal stresses resulting from temperature fluctuations. In the context of pressure vessels, certain types of vessels are more susceptible to this phenomenon due to their operating conditions.

Coke drums are specifically designed to handle the thermal cycling involved in the coking process, where feedstock is subjected to extreme temperatures during the conversion to petroleum coke. This process involves rapid heating and cooling cycles, which can induce significant thermal stresses in the material. As these cycles occur, especially in the transition phases between hot and cold, the material can expand and contract, leading to fatigue failures over time.

Other vessels, such as distillation columns and knockout drums, experience more stable temperature conditions during their operation. Distillation columns maintain a more constant temperature gradient as they separate components based on boiling points, and knockout drums are generally designed to handle liquid and gas separation without drastic thermal changes. Overhead accumulators, while they may experience some temperature variations, are also less prone to the severe thermal cycling characteristics associated with coke drums.

Therefore, the nature of the coke drum's operational cycle makes it the vessel most likely to be affected by thermal fatigue.