[TowerTalk] Corrosion;Coatings;Pinholes

[Pat Barthelow]

There have been discussions in the past about coating structural components 
of towers, including guy anchors, with various sealants from bituminous tar, 
to paint, zinc coatings, to whatever...
I understand the corrosion process is electrolytic, involving ionic 
transport and exchange through moisture. and minute electrical currents 
pushing the ions along,  in the process.

I wonder what the effect is on a structure that is protected over the vast 
majority of it's exposed surfaces, but has a few 'pinholes' in the 
protective coating, whatever it may be..zinc,paint, bituminous tar, etc.  If 
the moist soil or air, containing salts,  that is contributing the movement 
of ions and  oxidizing the exposed metal, can attack the unpotected surface 
through an undetected  pinhole, ionic current flows.  The current flow,  as  
a yardstick of the pace of the chemical reactions, is concentrated at a 
point location on the structure.   Does this point source corrosion do more 
damage, more quickly to a structure, than if large surface areas of the 
corrodable material were acted on more evenly over time?

73, de Pat AA6EG  aa6eg at hotmail.com


















73, DX, de Pat Barthelow  AA6EG
(831) 646-0388    aa6eg at hotmail.com