For soil-to-air inspections on uncoated lines, it is recommended to excavate the soil:

For soil-to-air inspections on uncoated lines, it is recommended to excavate the soil:

• A. 2-4 inches
• B. 6-12 inches
• C. 18-24 inches
• D. 1-2 feet

Answer: (B)

The key idea is to expose the pipe at the soil surface so you can visually inspect the exterior for corrosion where soil contacts air. On uncoated lines, there’s no protective coating to shield the metal from moisture and contaminants in the soil, so the ground-line area is where external corrosion is most likely to develop. Excavating to a depth of about 6 to 12 inches provides enough clearance to clearly view the pipe at the soil-air interface, assess the metal surface, and check for coating damage or signs of corrosion, without introducing unnecessary disturbance or risk from deeper excavation. Too shallow an excavation won’t reveal the critical area, while digging much deeper isn’t needed for this inspection and adds unnecessary risk and effort.

The key idea is to expose the pipe at the soil surface so you can visually inspect the exterior for corrosion where soil contacts air. On uncoated lines, there’s no protective coating to shield the metal from moisture and contaminants in the soil, so the ground-line area is where external corrosion is most likely to develop. Excavating to a depth of about 6 to 12 inches provides enough clearance to clearly view the pipe at the soil-air interface, assess the metal surface, and check for coating damage or signs of corrosion, without introducing unnecessary disturbance or risk from deeper excavation. Too shallow an excavation won’t reveal the critical area, while digging much deeper isn’t needed for this inspection and adds unnecessary risk and effort.