"pickling" is a process that involves hydrochloric or sulphuric acid, not phosphoric alone, and results in flash rusting, which is why most new plate steel you buy has an oily coating .... the ortho-phosphoric acid used for rust conversion [not removal] doesn't cause hydrogen embrittlement because the hydrogen is dissolved in the water not incorporated into the metal .... just don't heat the solution

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics