How should the butt welds in tank shells be examined according to the standards?

• A. By visual inspection only
• B. Visually, and by either RT or UT
• C. With a pressure test
• D. Using only ultrasonic testing

Answer: (B)

The correct approach for examining butt welds in tank shells according to API 650 standards is to use both visual inspection and supplementary methods such as radiographic testing (RT) or ultrasonic testing (UT). This comprehensive examination ensures a thorough assessment of the weld quality and integrity.

Visual inspection is important as it allows for the detection of surface defects such as cracks, undercuts, and incomplete fusion. However, some flaws may not be visible on the surface, which is where RT or UT comes into play. These non-destructive testing methods can reveal internal defects that might compromise the weld’s performance under stress or pressure.

Combining these methods provides a reliable means of ensuring that the welds meet the required specifications for structural integrity and safety, which is crucial in the context of oil storage tanks where leaks or failures can have severe consequences.

The other methods mentioned would not be sufficient alone. For example, relying solely on visual inspection does not provide a complete evaluation of potential internal flaws. Pressure testing, while useful in certain circumstances, does not specifically address the quality of welds themselves. Ultrasonic testing is valuable but, without the initial visual inspection, it may miss surface defects that could lead to failure. Thus, the adoption of both visual inspection and RT