Vessels in cyclic service should be inspected primarily for:

Vessels in cyclic service should be inspected primarily for:

• A. Creep
• B. Excessive strain
• C. Fatigue
• D. Stress corrosion cracking

Answer: (C)

Vessels operating in cyclic service experience repeated loading and unloading cycles that can lead to the development of fatigue in the materials. Fatigue occurs due to the accumulation of damage as a result of these repetitive stress cycles, which can cause microcracks to form and eventually grow, leading to potential failure. Inspections for vessels in cyclic service focus on identifying signs of fatigue, such as surface cracks or changes in material properties, which can help in assessing the structural integrity and safety of the vessel. This focus is critical because fatigue failures can occur without any prior warning, making it essential to monitor for conditions that may contribute to such failures. Understanding this, the other options are also relevant to pressure vessel integrity but are less critical in the context of cyclic loading. Creep, for instance, occurs primarily under constant load and high temperature over time rather than from cyclic stresses. Excessive strain might result from overloading rather than cyclic operation. Stress corrosion cracking, while a serious concern, is specifically related to corrosion processes in the presence of tensile stress and certain environmental conditions, rather than the repetitive nature of cyclic service. Thus, while all these factors are important for overall vessel integrity, fatigue is the primary concern for vessels subjected to cyclic loading.

Vessels operating in cyclic service experience repeated loading and unloading cycles that can lead to the development of fatigue in the materials. Fatigue occurs due to the accumulation of damage as a result of these repetitive stress cycles, which can cause microcracks to form and eventually grow, leading to potential failure.

Inspections for vessels in cyclic service focus on identifying signs of fatigue, such as surface cracks or changes in material properties, which can help in assessing the structural integrity and safety of the vessel. This focus is critical because fatigue failures can occur without any prior warning, making it essential to monitor for conditions that may contribute to such failures.

Understanding this, the other options are also relevant to pressure vessel integrity but are less critical in the context of cyclic loading. Creep, for instance, occurs primarily under constant load and high temperature over time rather than from cyclic stresses. Excessive strain might result from overloading rather than cyclic operation. Stress corrosion cracking, while a serious concern, is specifically related to corrosion processes in the presence of tensile stress and certain environmental conditions, rather than the repetitive nature of cyclic service. Thus, while all these factors are important for overall vessel integrity, fatigue is the primary concern for vessels subjected to cyclic loading.