What steps would you take to prevent corrosion when bolting aluminum components to steel?

• A. Do not torque at all.
• B. Use isolation products (gasket, insulating washers), avoid galvanic contact; apply appropriate coatings; ensure proper torque.
• C. Use stainless steel components only.
• D. Avoid galvanic contact entirely by not using any coatings.

Answer: (B)

The key idea is preventing galvanic corrosion when aluminum and steel are in electrical contact in a moist environment. Aluminum is more anodic than steel, so when they touch, electrons flow and the aluminum tends to corrode faster. To stop that, you break the electrical path and block ion transfer at the joint. Using isolation products like gaskets or insulating washers keeps the metal surfaces apart so the galvanic couple can’t form. Adding coatings creates a barrier that prevents direct metal-to-metal contact and slows or stops corrosion at the interface. And applying the correct torque is essential: it preserves a tight, sealed joint, minimizes micromotion and water intrusion, and ensures the barrier remains effective without damaging the parts or the coating.

In practice, you would place an insulating washer or gasket between the bolt head (or nut) and one surface, coat the contact areas with a suitable barrier coating if needed, and torque to the specified value so the joint stays tight and protected over time. Using only stainless steel components or failing to isolate the metals does not address the galvanic path and can still lead to corrosion, and not torqueing at all would allow movement and leaks.