pan, the smoker floor, and the heat shield with HD foil before every smoke, and things still look pretty new. I do know that Al foil is easily corroded over time from experience with the foil pan liner in my gas grill. If I don't replace it every month or so, it corrodes through...
Metals may corrode by pitting corrosion wherein tiny pits form along the length of the pipe diminishing the pipe’s wall thickness and reducing its pressure bearing capability. Another cause for concern is crevice corrosion. This is where ions in the fluid concentrate in crevices around welds, ...