What should be done before plugging a crack in a bulkhead to prevent it from spreading?

What should be done before plugging a crack in a bulkhead to prevent it from spreading?

• A. Drill holes of 1/4 inch at the extreme ends of the cracks
• B. Seal crack with putty
• C. Weld first
• D. Open the space to atmosphere

Answer: (A)

Relieving stress at the ends of a crack by drilling stop-holes is done before plugging to prevent crack growth. Making small holes, about 1/4 inch, at the extreme ends of the crack stops the crack from propagating when you apply a patch or seal. The holes relieve the stress concentration at the crack tips and provide a clean boundary where the patch can bond, reducing the chance that the crack will run farther as pressures and vibrations act on the bulkhead. Sealing with putty alone won’t stop the crack from growing, and welding first isn’t necessary for a simple crack before patching. Opening the space to atmosphere would invite corrosion and moisture intrusion and could encourage the crack to spread.

Relieving stress at the ends of a crack by drilling stop-holes is done before plugging to prevent crack growth. Making small holes, about 1/4 inch, at the extreme ends of the crack stops the crack from propagating when you apply a patch or seal. The holes relieve the stress concentration at the crack tips and provide a clean boundary where the patch can bond, reducing the chance that the crack will run farther as pressures and vibrations act on the bulkhead.

Sealing with putty alone won’t stop the crack from growing, and welding first isn’t necessary for a simple crack before patching. Opening the space to atmosphere would invite corrosion and moisture intrusion and could encourage the crack to spread.