What is the requirement for additional spot radiographs when dealing with vertical welds of greater than 1 inch?

• A. Every 50 feet of vertical weld
• B. Every 100 feet of vertical weld
• C. Every 150 feet of vertical weld
• D. Every 200 feet of vertical weld

Answer: (B)

The requirement for additional spot radiographs for vertical welds greater than 1 inch is established to ensure the quality and integrity of the welds in the tank construction. In this context, conducting radiographic examination at intervals serves as a quality control measure to identify any potential defects in the welds that may not be visible through standard visual inspections.

Selecting an interval of every 100 feet of vertical weld aligns with the established standards in the API 650 specification. This specific interval is seen as a balance between adequate inspection coverage and the practicality of the inspection process. By performing radiographs every 100 feet, it helps ensure that any issues related to weld quality can be detected in a timely manner, which is critical for maintaining the safety and reliability of oil storage tanks.

In contrast, shorter or longer intervals may not provide the same level of thorough inspection coverage or could lead to excessive operational costs or time delays, thus compromising the efficiency of the construction and safety standards.