I would not sweat what H2O Head is saying. I agree with your tech that it is not an issue. The heat treated aluminum used n scuba tanks is not so soft as to be susceptible to having bits of steel wool embedded in it any more than the aluminum would be subject to having bits of metal from a steel tank rack embedded in it, or even more commonly, from having steel embedded in it during the drawing process when the tank was manufactured.
There is some truth to what he is saying with respect to clad aluminum alloys where a corrosion resitant AL coating can be polished away leaving a much more susceptible Al alloy exposed. But still in this case it is not disimilar metal corrosion but rather the exposure of a more corrosion prone alloy that leads to the corrosion.
In any event, corrosion in most aluminum alloys is a largely self limiting process unless it is continuously exposed to salt water.
There ARE concerns for dismiliar metal corrosion in all AL scuba tanks bu they stem from the brass valves you stick in the tank. It's one of the primary reasons that the threads on the valve are lubricated - to prevent the removal of the chrome plating, and to curtail disimiliar metal corrosion and to prevent it from corroding the valve in place in the event brass is exposed in the threads.
Disimilar metals corroison can also be an issue with double tank bands on Al tanks, but again a major contibuting factor is one of moisture and salt crystals getting trapped for significant periods of time between the bands and tanks. A bit of vinyl electrical tape on the inside of the bands is then needed to curtail the galvanic action that can occur.
And a final comment... A lot of people seem to be really excited about the recent offer by Luxfer for a $50 credit toward a new tank for old tanks of 6061 T-3 aluminum. Personally I feel that if you do an eddy current check at least every 18 months and don't overfill the tank, you really have nothing to worry about and the tank is worth far more to an active diver than a $50 credit on a new one.
There is some truth to what he is saying with respect to clad aluminum alloys where a corrosion resitant AL coating can be polished away leaving a much more susceptible Al alloy exposed. But still in this case it is not disimilar metal corrosion but rather the exposure of a more corrosion prone alloy that leads to the corrosion.
In any event, corrosion in most aluminum alloys is a largely self limiting process unless it is continuously exposed to salt water.
There ARE concerns for dismiliar metal corrosion in all AL scuba tanks bu they stem from the brass valves you stick in the tank. It's one of the primary reasons that the threads on the valve are lubricated - to prevent the removal of the chrome plating, and to curtail disimiliar metal corrosion and to prevent it from corroding the valve in place in the event brass is exposed in the threads.
Disimilar metals corroison can also be an issue with double tank bands on Al tanks, but again a major contibuting factor is one of moisture and salt crystals getting trapped for significant periods of time between the bands and tanks. A bit of vinyl electrical tape on the inside of the bands is then needed to curtail the galvanic action that can occur.
And a final comment... A lot of people seem to be really excited about the recent offer by Luxfer for a $50 credit toward a new tank for old tanks of 6061 T-3 aluminum. Personally I feel that if you do an eddy current check at least every 18 months and don't overfill the tank, you really have nothing to worry about and the tank is worth far more to an active diver than a $50 credit on a new one.
