Page 155 - Corrosion Engineering Principles and Practice
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130 C h a p t e r 5 C o r r o s i o n K i n e t i c s a n d A p p l i c a t i o n s o f E l e c t r o c h e m i s t r y 131
10 80
Current at Tower Base
8
70
6 60
Current (mA) 4 Potential at Tower Base 50 Potential (mV)
2
40
0
Current and Potential at Elevated Position in Tower
(No Measurable Value)
–2 30
0 500 1000 1500 2000
Time (Seconds)
FIGURE 5.35 Potential and current noise records at two locations in a gas
scrubbing tower.
An improvement over this simple analysis is commonly practiced
in industry by tracking the width of the potential and current signals
as an indication of corrosion activity in the system being monitored.
Fig. 5.37 illustrates how the decrease in the current band obtained
with a monitoring system was interpreted as a reduction in general
corrosion activity in a debutanizer overhead piping where the
interaction between operational changes and the corrosion mechanism
were being investigated.
FIGURE 5.36 Scanning electron microscope image of a sensor element
surface after exposure at the base of the scrubbing tower clearly showing
corrosion pits.
