Galvanic reaction

    **** Moderator's comments: This posting is a response to a
    private query from structural engineer Hans E. Boge, of Boge
    Boge (1980) Ltd., who was seeking an online reference outlining
    the galvanic series

Between mid-1979 and mid-1985, the State of California Office of the
State Architect performed repairs using stainless steel on the
National Historic Landmark in Los Angeles Watts Towers of Simon
Rodia, 3 tallest sculptures. The sculptures are 55 feet tall to 99
feet 6 inches tall of cement mortar, coverings over slender columns
and bands with steel reinforcements using long angles and channels
from standard shapes of the 1920s. The steel reinforcements used by
the artist, Simon Rodia, are mild steel, circa 1921 from suppliers
in the Watts district of Los Angeles, California.

>From 1989 to 1991 the sculptures were repaired by the State of
California Office of the State Architect crews. Large cracks were
later observed in the covers of the composite columns at the
48-foot elevation level and at other levels. After the 1994
Northridge Earthquake, disassembly and analyses for a following plan
of repairs and conservation showed that the stainless steel used as
repairs for the original mild steel reinforcements had "eaten away"
much of the original mild steel, causing expansion of the, mild
steel remainders and large, wide, deep and long cracks in the
resultant repairs of cement over the original columns and bands.

The work of repair in 1979 to 1985 using stainless steel for
replacement reinforcements was done by the State of California,
Office of the State Architect. Current head of the State Parks,
responsible for the Watts Towers now in Los Angeles, is Ted Jackson,
Jr. at 213-620-6152 <tjack [at] parks__ca__gov>. Records are also at the
City conservation trailer in Watts at 1756 East 107th Street in Los
Angeles under control of Virginia Kazor at vkazor [at] cad__lacity__org.

Caution in selection of steel for reinforcements is needed when
repairing or replacing mild (low carbon) steel reinforcements with
stainless in older structures, dams, bridges, buildings and other
constructions! It will save a lot of later work and funds.

Bud Goldstone


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                  Conservation DistList Instance 17:43
               Distributed: Wednesday, November 26, 2003
                       Message Id: cdl-17-43-008
                                  ***