Tunnel furnaces (or roller hearth slab reheat furnaces) provide one of the toughest environments for cast steel fabrications. With temperatures approaching 2300° F, these rolls are expected to carry the full weight of the slab being heated to rolling temperatures. Duraloy's dry rolls, manufactured in our proprietary alloys, have proven themselves as the best rolls in the world. Dry rolls provide several advantages over "wet" or water-cooled rolls. First, in a tunnel furnace transfer car, they eliminate the need for flexible water hoses to be hanging from the shuttle. Dry rolls minimize heat loss in the furnace, reducing energy consumption. Duraloy's proprietary MO-RE 2150® alloy has allowed furnace operators to retrofit entire furnaces with dry rolls.
Water cooled rolls are found in CSP tunnel furnaces around the world. The rolls have a carbon steel tubular shaft with a stainless steel "corebuster" installed in the shaft to direct water flow through the roll. Cast tyres are then welded to the shaft to provide the carrying surface for the slabs in the furnace. The areas between the tyres are covered with a castable ceramic material to insulate and protect the shaft. Duraloy has supplied thousands of water cooled rolls.
Duraloy produces a these large diameter rolls, typically used in continuous annealing or continuous galvanizing lines. The rolls are produced with centrifugally cast bodies up to 54" (1370 mm) in diameter. The ends are statically cast and the shafts are typically wrought materials. All the parts are fabricated in house and finish machined to customer specifications. The rolls can also be supplied static or dynamically balanced, if required. Typical alloys of construction are HF, HK, MO-RE® 1 and MO-RE® 2.
These statically cast rider blocks are used to carry slabs through a reheat furnace. The slabs are heated up prior to being rolled into plate or sheet. These rider blocks are normally pinned to an underlying skid and are designed to keep the slab elevated off of the skid to avoid scratching the slab surface and provide for more even heating. Skid riders are normally cast in very high alloys, such as Duraloy's proprietary alloys MO-RE® 1, MO-RE® 2, 22H® or Super 22H®.
These very large radiant tube assemblies are cast, machined and fully fabricated at Duraloy. The size of the assembly is dictated by the size of the furnace and the amount of heat that is required by the furnace design. These radiant tube assemblies are cast in Duraloy's proprietary alloy Super 22H®. alloy.
These rolls are used in a roller hearth, plate hardening furnace in the steel industry. The roll is fabricated from a centrifugally cast barrel, two statically cast roll ends and shafts made from forged bar. Depending on the customer requirements, rolls such as these can be statically balanced, dynamically balanced, coated, machined, etc., as designed and specified by the customer order.