Ingenuity Magazine Fall 2020

Pond Ingenuity Fall 2020 11 over a properly prepared surface, under the required conditions in order to maximize service life. The process is detailed in Figure 2. The pipe must first be blast-cleaned to the specified level of cleanliness, with the specified roughness and anchor profile. Then the pipe is passed through a furnace to heat the surface and then, the charged epoxy powder is blown onto the oppositely charged metal surface, where it melts and fuses to the surface. The pipeline is then quenched, holiday tested and shipped to the site or to a staging location prior to field installation. As with any manufacturing process, a certain amount of “rejects” are inherent in the process. Defects may be generated at the pipe mill and may make it to the coating plant. A critical part of the inspection process is to identify mechanical damage of the pipe either pre- or post-coating. Another source of coating or mechanical defects is during the installation process—from movement or transport to the jobsite, from transport to yard, or from the yard to in-situ. After a pipeline is placed into service, the corrosion system performance is monitored. A DCVG investigation identified locations of coating defects from the coating process or from mechanical damage of the pipeline coating. Locations identified with coating defects were identified, and confirmatory digs were scheduled. Several different defects were identified. One area exhibited mechanical damage that was coated over at the plant, as shown in Figure 3. The mechanical damage occurred prior to the coating process and appears to have been missed during inspection. Another location exhibited coating damage during the installation process, as show in Figure 4. A properly applied FBE system would be tightly adherent and should resist delamination. It should only be scratched by probing with a knife. This investigation showed that the FBE was lifted by knife probing with the surface beneath the FBE exhibiting mill scale and surface corrosion, as shown in Figure 5. After the field investigation, it was discovered that client did have 3rd party inspection at the plant during the coating application process. A cursory review of the inspection records showed that the inspection team on site did not reject a single section of pipe during the entire run of over 35,000 linear feet. In any manufacturing process, a certain percentage of defects are found. The fact that no defects were found, and that the coatings were all identified as applied within the specified range of dry film thickness, without a single section being rejected, called into question the skills of the inspection personnel assigned to the project. Further investigation revealed that the inspectors had no formalized training in coatings inspection. If there are no identified discrepancy with any of the materials, it is likely that they did not undergo meticulous inspection. Clients need a trusted partner to spot errors and verify the coatings are applied correctly during the procurement process. Without qualified coating inspectors, coating failures and mechanical defects are about the only “guarantee” the purchasing agent can bet on. David A. Hunter, PCS, Principal, Coatings Program Manager, Protective Coatings Specialist • Reprinted with permission from Paint Square Press Digging these trenches and putting up (shoring) walls to prevent collapse is a tedious, costly endeavor Figure 4 Figure 5