Great tip. To avoid problems though, just don't put wet coal in a hopper. That's asking for trouble. I have a list of things I do to my boiler every spring to prep it for summer shut down. Cleaning, prepping and painting the hopper is always on that list but honestly I've never had to do it. The hopper still looks like new inside at 10 years. No corrosion ever and it's not even painted. Harman doesn't paint the inside of the hoppers. It has seen damp coal but never wet. On the other hand several of the mag stokers I've bought to refurb have had corrosion. Once prepped, I like the truck liner idea.