Ceramic fiber module has been main insulation materials for the well type electric resistance furnace of my company, the appearance can be designed into round pit type resistance furnace, or polygon pit type resistance furnace according to customers' requirements . In order to save the workpiece lifting space ,pit type resistance furnace is often installed underground, only the furnace door system is placed on the ground.Of which pit types furnace that needs to add the protective atmosphere and vacuum furnace are usually placed underground, its security can be guaranteed perfectly .