Page 241 - Corrosion Engineering Principles and Practice

216 C h a p t e r 7 C o r r o s i o n F a i l u r e s , F a c t o r s , a n d C e l l s 217

FIGURE 7.5 Pits in 16-inch sheet iron water main in San Francisco’s East Bay
that failed in one month due to leakage of current from electric streetcars.
(Photo dated August 10, 1926, Courtesy of East Bay Municipal Utility District).

As written in a book published in 1906 [10], “Electrolysis is a disease
most largely peculiar to America. The Europeans have experienced
little trouble from the corrosive action of return currents, but the
reports of the ‘horrible’ cases in this country aroused their fears and
they at once set to work to determine the state of affairs in their own
countries.”

7.3 Identifying the Corrosion Factors
The factors listed earlier have been organized in a framework of six
categories with a number of subfactors as shown in Table 7.3. According
to Staehle’s materials degradation model, all engineering materials
are reactive and their strength is quantifiable, provided that all the
variables involved in a given situation are properly diagnosed and
their interactions understood [11]. The corrosion-based design analysis
(CBDA) approach was further developed from the initial framework
as a series of knowledge elicitation steps to guide maintenance and
inspection decisions on the basis of first principles [12].