I was a P1 pipe welder at the Philadelphia Naval Shipyard. During my apprenticeship one of the requirements we had to learn to be proficient at was welding aluminum. I say this because the naval destroyers had aluminum superstructures attached to a steel hull, so everything above the main deck was made of aluminum. There was an insulating layer sandwitched between the two dissimilar metals at the contact point to eliminate the corrosion problem. The superstructure was bolted/riveted to the hull since welding the two together was not possible.
