Which practice reduces concentration cell corrosion during maintenance?

• A. Apply water-soluble oils to joints
• B. Avoid the creation of crevices during repair work
• C. Use bare metal in all joints
• D. Increase crevice formation

Answer: (B)

Concentration cell corrosion occurs when adjacent metal surfaces are exposed to different chemical environments, creating a tiny galvanic cell. Crevices trap moisture and create a stagnant, oxygen-depleted zone inside the gap, while the surrounding metal remains more oxygen-rich. This differential aeration drives corrosion inside the crevice much faster than on the open surface. So, during maintenance, avoiding the creation of crevices—keeping joints smooth, flush, and properly sealed—eliminates the local conditions that fuel concentration cell corrosion, reducing the overall corrosion risk.

Other options don’t address this issue as effectively: applying water-soluble oils can shed some moisture but doesn’t remove crevices or the differential environments; using bare metal in joints increases exposed area and vulnerability to corrosion; increasing crevice formation directly promotes the very conditions that drive concentration cell corrosion.