Crown-Sheet

In a steam boiler. plate directly over the fire-grate. In locomotive practice it is either flat or slightly arched, and is stayed from collapse inward and downward either by flat crown-bars or by radial stay bolts. The total pre ure upon the crown-sheet of a furnace whose area is 64 sq. ft. with a boiler pre ure of 140 lbs. to the sq. in. amounts to 645 tons.