The input data required to perform the external corrosion mechanism review typically includes:
Number, location and data sheet of CP rectifiers
Number and position of sacrificial anode beds
Recent Close Interval Survey (CIS)
Recent Direct Current Voltage Gradient (DCVG)
Coating type and installation date.
Any information regarding coating condition
Elevation profile
Soil type, resistivity and pH
Historic failure due to external corrosion data
Repair history
THE MECHANISM REVIEW WOULD
Align all data on a common reference for comparison purposes.
Review the above ground surveys and correlate to any ILI results establishing the theoretical hotspots and estimate potential corrosion growth rates. This could then be compared and contrasted to the results of any corrosion growth assessment performed.
Provide discussion of possible external corrosion mechanisms present.
Provide recommendations for external corrosion management.