Abstract
This paper compares the results of cathodic potential tests including and excluding IR drop and with the reference electrode both over and remote from the pipe.
Results of using the break in the current potential curve as a criterion for protection are compared with lowering the pipe potential —0.3 volt and to —0.85 volt. The criteria do not agree.
Results of increasing the test current in equal steps are compared with those obtained by increasing the current by 50 percent increments. Equal current increments give smoother curves.
The necessity for equally spaced times of potential observations is discussed. This is desirable but not always necessary.
Data plotted on rectangular coordinate paper are compared with the same data plotted on semilog paper. Sometimes it is best to use both methods.
