What additional requirement is there for each additional 100 feet of vertical weld?

• A. No extra requirements
• B. One additional radiograph
• C. Additional spot radiographs required
• D. Increased inspection frequency

Answer: (C)

For each additional 100 feet of vertical weld in the context of API 650, the correct requirement is to have additional spot radiographs conducted. This is essential because larger weld lengths can introduce more potential for defects, and thus, increased inspection through spot radiography helps ensure the integrity and quality of the welds throughout the entire length of the tank.

Spot radiographs serve as a method to detect any issues that might arise in the welds, such as incomplete fusion or porosity, ensuring that any potential problems can be identified and addressed early in the construction or maintenance phase. This practice is part of ensuring compliance with quality assurance measures outlined in the API 650 standard, which ultimately contributes to the safety and durability of the welded tanks designed for oil storage.

While options like increased inspection frequency or additional radiographs might be logical considerations, they do not specifically address the requirement laid out in API 650 regarding extensive vertical welds, making additional spot radiographs the appropriate response to enhance quality control.