The answer to "why not 'just' regalvanize?" lies
with the distance to the galvanizing outfit, and
the galvanizing cost, plus the condition of the tower.
It's not cheap to do, particularly if you have to
truck the load several hundred miles each way.
In addition, most galvanizers won't touch a rusted
structure. You can't zinc plate over iron oxide.
So if you see internal rust, it's probably a lost cause.
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