Which bolt specification is required when test blinds are installed?

• A. Shorter bolts
• B. Longer bolts
• C. Bolts of the same length as service bolts
• D. No bolts required

Answer: (B)

When test blinds are installed, there’s extra material added to the mounting (the blind plate plus any gasket). To maintain proper thread engagement and the clamping force needed to hold the blind securely during testing, you need bolts that are longer than the service bolts used in normal operation. Longer bolts ensure the threads stay engaged and the blind is tightly secured, preventing leaks or movement under test pressure. Using shorter bolts could bottom out or fail to draw the plate tight enough, and bolts the same length as service bolts wouldn’t account for the added thickness. Not using bolts at all would leave the closure unsafe.