While time and money are always lost when faced with a premature coatings or linings failure, the biggest loss is often that of reputation.
Mike O’Brien of MARK 10 Research Group, Inc., made that clear during a presentation at the recent 2023 AMPP Annual Conference + Expo, titled “Why Do Coatings & Linings Systems Fail Prematurely? How to Investigate Premature Failures When They Occur.”
“The common denominator in all premature coating failures is people,” O’Brien says. It’s people, not processes, that most often cause failures, ranging from the specifier to the inspector.
He cited one example (out of many) of pipes in the process of being installed in a desert environment for potable water transport. Cracking was observed and the linings investigated.
One of the constants of the investigation was that any cracking that occurred was within the 9 o’clock and 3 o’clock pipe orientation, or the part of the pipes that were in direct sunlight. On the same pipes, the areas between 4 o’clock and 8 o’clock were clear of cracking, even when they were on the same weld.
Also, the pipe contractor’s stated deliverable—and motivation—was to get the pipes to the right-of-way (ROW), resulting in some of the pipes being at the ROW for over 20 months.
After an extensive range of testing procedures, including SEM/EDX and GC/MS, were completed, it was discovered that benzyl alcohol and other solvents were leaving the lining in various amounts, and that the amount leaving the film depended upon the position of the lining within the pipe and upon duration on the ROW.
The temperature range of the environment in which the pipes were located varied from 60-70 °C (140-158 °F) during the day and 3-4 °C (37-39 °F) at night, causing the pipe to go above the glass transition temperature (Tg) during the day, and below the Tg at night.
Ultimately, if the specifier and coating manufacturer knew the pipes would be under such severe conditions for so long, they could have selected a different lining. Or, if someone had been contracted to expertly cover the pipes once at the ROW, the original lining would have sufficed.
Sometimes a reputation can be saved via a handshake, and appropriate contractual specifications.
Source: 2023 AMPP Show Daily, showdaily.ampp.org.