As much as this appears to be a coatings issue, it is an HRSG (heat recovery steam generator) erection problem. More specifically, a range of problems which result in hot gases coming in contact with the casing.
In the 12 units inspected at one site, all of them had visible indications of external coating damage from excessive temperatures.
Those same units were internally inspected, and the list of erection defects was extensive. Well beyond the issues that related to hot spots.
Some of the issues were missing insulation, liner damage, missing liner panels, buckled flashing, and other assembly problems.
When EPR gets involved at a site where there is visible external damage to HRSG coatings, we usually consider it an indicator of much more extensive internal problems mostly unrelated to this issue. So far, this has been accurate.
Once the HRSG problems are resolved, the hot spots can be remediated with new coatings applied using an appropriate repair procedure.
Cost is mostly due to poor thermal operation of the HRSG’s.