Abstract: The present invention provides an inexpensive furnace modification which increases the productivity of the furnaces without requiring extensions to the furnace member or the surrounding building. Existing inner covers are extended a predetermined amount to accommodate the additional steel product within the volume defined by the inner cover. This is done by either adding a section to an existing inner cover, or by providing new covers of increased height. A ring structure of the predetermined additional height required and having the same diameter as the furnace member is placed over the inner cover and positioned to rest on the furnace base so that it encircles a portion of the inner cover. The furnace member is then placed over the inner cover and positioned to rest on the ring. Preferably, both the ring and the furnace member have annular locating lugs which coact with locating posts adjacent the base.