I don't suppose you guys set it on fire deliberately because it's the fast way to clean it out....
No, for certain products which have multiple layers, we have to run the heats near the burning point to get bond. When we are done with a run, it is a race to disassemble the head before what is left on the mandrel after purging burns. It is a lot more difficult to get off burnt pvc. When it doesn't burn, it peels right off..l