Combustion air intake preheat duct for API refinery furnace complete with insulation, ready for shipment. Combustion air preheat duct for Shell Scotford. Vertical cylindrical process furnace shell panels under construction for the Husky refinery in Lima, Ohio. Access man-way panel in flue gas recirculation duct system. Flue gas recirculation duct under construction; showing lift lugs MPI. Flue gas recirculation ducts being prepared for final finish coat prior to shipment to a US gulf coast refinery. Castable refractory insulated flue gas duct insert for isolation guillotine (field installed). Structural components of a combustion air preheat assembly on an API refinery process furnace.