Recently, a power company identified their current procedures for corrosion protection with industrial coatings of pipe cable sections as an opportunity for process improvement. The power company sought to decrease the difficulty of maintaining coatings on these assets, increase the service life of the coating systems, and decrease life cycle cost. This presentation will provide a narrative of the steps taken during the process improvement, i.e., evaluation of the current paradigm, development of improved procedures and identification of better materials afforded through advances in coatings technology, implementation of the improvements, and lessons learned.
Recently, a power company was not satisfied with the performance of the coatings they were applying to pipe cables. The pipe cables are steel protective covering for conductors transmitting as much as 140,000 volts. The pipe cables are filled with pressurized oil or nitrogen to prevent internal corrosion and short circuiting. The pipe cables are buried with exception of intermittent concrete underground concrete chambers. For oil filled pipe cables the chambers provide for access to valves for sampling and inspecting the oil. Manholes provide access to the chambers. The chambers frequently fill with stormwater and the pipe cables are immersed. This environment and set of circumstance pose many challenges for external corrosion protection of the pipe cables with coatings including limited access, confined space, immersion, high humidity, and poor visibility. Coatings were failing prematurely, and the company engaged a corrosion and coatings consulting company to develop process improvement to increase coatings service life and decrease life cycle cost.
Premature coating failures are typically caused by inadequate surface preparation, faulty application, or improper material selection. To identify the cause and recommend process improvement the consultant used a two-step technical approach – (1) Review of Background Information, and (2) Existing Coatings Condition Assessment.
The Consultant interviewed the client, reviewed current client specifications, QA/QC practices, and previous inspection reports. The consultant learned through discussions with the client performed by a contracted asset maintenance firm. The spot repair maintenance painting tasks are completed by personnel without specific coatings training responsible for other maintenance activities. Comprehensive specifications are not used however, the surface preparation and coating products requirements are included in the task orders in a general standard, table format. The utility had been using mostly bitumastic as the standard coating system and in some instances used a silicone coating for spot repairs. Review of QA/QC practices revealed critical inspections were not being conducted, e.g., monitoring of ambient conditions, soluble salt testing, by the maintenance personnel. Lastly, third party inspection had not been used.