[Bell Historians] Steelwork into masonary, wet towers

[Bickerton, Roderic K (SELEX) (UK)]

What is the current thinking on a wet tower , one where the inside walls
run with water and a cocktail of chemicals leeched from the stonework,
topped up with some acid rain salt mist and  pollution, and considerably
upped in strength by evaporation of the carry water?

Galvanising is good but I doubt under such conditions it would be good
for that many years.
Loss rates for external exposure vary between 1 and 2.5 micro meter/year
which is not that long even with 55 micro meter cover.
Loss rates can be higher at the interface between stonework and steel
with leeched chemicals and pollutants present.
Concrete is very benign in that it protects rather than attacks steel,
but in wet conditions the chemicals in the cement providing protection
are quickly leached at the interface between concrete and air in the
presence of water which alternately flows and evaporates.



In the end this is fare more important than the odd job that needs early
remedial action, because it occurs well after any responsibility has
been discharged.
Bell installations should be designed so that with maintenance the
structural components should have a 200year+ life. 
Timber frames have managed that and more, without modern insectersides
and fungicides.

~Various sources predict life
Links
http://www.blake-uk.com/index_galvanising.aspx
http://www.thefabricator.com/MetalsMaterials/MetalsMaterials_Article.cfm
?ID=588




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