COATINGS & LININGS FIGURE 2
bonded coatings. The percent IR indi- cates the voltage gradient strength (amount of current being consumed at the defect) but does not indicate whether there is corrosion, SCC, or disbonded coating.
Case Studies The following two case studies show
examples of failure modes for two differ- ent coating systems. They illustrate the importance of coating disbondment de- tection as a tool for maintaining a pipe- line's integrity. Figure 2 shows a liquid epoxy repair
Disbonded two-part epoxy repair found with EMAT.
pipelines. These surveys can provide some indications of where the coating has holidays or damage that expose pipe steel.
Traditional annual CP and CIS will
provide information about the coating condition and potential degradation, but do not provide information critical to determining if there are coating disbond- UMV\[