Which of the following would not be considered a major repair according to API 653?

Which of the following would not be considered a major repair according to API 653?

• A. Installing a bottom penetration within 12" of the shell
• B. Installing shell penetration larger than NPS 12 beneath the design liquid level
• C. Removing and replacing the entire roof of a cone roof tank
• D. Removing and replacing or adding a shell plate beneath the design liquid level where the longest dimension of the replacement plate exceeds 12"

Answer: (C)

The option indicating the removal and replacement of the entire roof of a cone roof tank is not classified as a major repair according to API 653 guidelines because the standard specifically delineates what constitutes a major repair. Major repairs usually involve significant alterations or replacements that affect the structural integrity or function of the tank. In the case of removing and replacing the entire roof, while it is a substantial task, it does not fall under the same category as alterations occurring underneath the design liquid level, such as penetrations in the shell or bottom of the tank. The tank roof is not typically associated with the primary structural elements that compromise the vessel's overall integrity, especially when compared to the implications of alterations at or below the design liquid level, which can have more critical consequences regarding the tank's stability and operational safety. By contrast, the other scenarios presented involve critical structural modifications that are likely to affect the tank's integrity and safety, particularly when they occur close to or below the liquid level, where stress and pressure considerations are heightened.

The option indicating the removal and replacement of the entire roof of a cone roof tank is not classified as a major repair according to API 653 guidelines because the standard specifically delineates what constitutes a major repair. Major repairs usually involve significant alterations or replacements that affect the structural integrity or function of the tank.

In the case of removing and replacing the entire roof, while it is a substantial task, it does not fall under the same category as alterations occurring underneath the design liquid level, such as penetrations in the shell or bottom of the tank. The tank roof is not typically associated with the primary structural elements that compromise the vessel's overall integrity, especially when compared to the implications of alterations at or below the design liquid level, which can have more critical consequences regarding the tank's stability and operational safety.

By contrast, the other scenarios presented involve critical structural modifications that are likely to affect the tank's integrity and safety, particularly when they occur close to or below the liquid level, where stress and pressure considerations are heightened.