Chuck,
first of all, let me tell you that I'm most happy to see you back in the Forum. Believe me, I've remembered you in my prayers all of these days.
Second, let me desagree with you. Pickling is used also for carbon steel. Example: before putting a turbine generator or a turbo compressor in operation, the lube oil piping system must be pickled to remove the oxyde, rust and debris in the pipes inner surface. This is true also for oil refineries and petrochemical plants, where some piping systems must be pickled before putting them in sevice.
Back in my days of erector engineer I took part in the erection of a few turbine generators, turbo compressors and one oil refinery and remember very well that the operation was carried out. What I don't remember, though, is the chemical composition of the pickling solution. It consisted in acids to remove rust, solvents to remove oil and grease and inhibitors whose function was to let the acids "eat" the rust and oxyde but prevented them from attacking the carbon steel. But I don't remember the percentages.
Giovanni S. Crisi