Fired heaters come in all sizes and configurations from small cylindrical heaters to large coker furnaces, crude heaters, or hydrogen reformers. Most of these heaters have refractory linings in the radiant sections (floor), convection sections, SCR, air pre-heaters/ducts, and the stacks. The insulating castables in these sections contain large quantities of free water that can be removed with a low temperature dryout to about 800F (425C). These low temperature dryouts have been an effective countermeasure to combat the alkalai hydrolysis problems that have been experienced in the industry.