This Technical Information Paper (TIP) provides guidelines for inspecting cylindrical, steam-heated pressure vessels made from gray cast iron (GCI) and used as rotating dryers in papermaking. These guidelines also apply to unheated GCI cylinders of the same construction. Large Yankee dryers typically used on tissue machines are not addressed in this TIP.

These guidelines are limited to inspection of the dryer pressure vessels themselves. Inspection of related steam and condensate piping, relief valves, bearings and gears, and doctoring devices is not directly covered. Nevertheless, the inspector should report unusual symptoms and conditions in those components and include that information in the inspection findings as soon as they are detected, in order to prioritize the suspect dryers for detailed inspection at the earliest opportunity in the "out of operation" mode (i.e., during a dryer shutdown).