CORRUGATED FURNACE TUBES.— Furnace tubes which are corrugated in their longitudinal sections. They are exten sively used both in land and marine boilers. The elastic character of the corrugations absorbs the linear expansion of the tubes under the influence of heat, and thus prevents the strains which tend to bulge the end-plates of the boiler. The heating tubes in a vertical or cross-tube boiler. They pass through the fire-box, and therefore, being surrounded by the fire, materially assist in main taining a rapid circulation of the water. They are cleaned through a mud-door placed opposite the end of each tube. The boiler crown proper is the uppermost plate in the shell of the boiler. It is formed either in the shape of a hollow disc flanged around the edges. and by which it is riveted to the outer shell-plates, or It is made flat and secured in place by means of stays. That portion of the crown which lies over the top of the furnace or inner shell is usually designated as the fire-box crown.
The plate, cover or valve, employed for regulat ing the amount of draught in a boiler or furnace flue. The contrivance is usually balanced with a weight called the damper-weight which assists in its adjustment.
The cast-iron plate which lies immediately within the furnace door of an engine boiler. It is provided for the reception, and for the partial coking, of the coal be, fore it is passed forward onto the grate.
DEAD The water which lies below the heating surface of the boiler, and, therefore, is in comparatively slow circulation. In some forms of boilers the flues are brought forward under the bottom so as to heat the dead water and thus induce a more rapid circulation therein.
A riveting tool used by boilermakers for holding under the heads of rivets during the act of riveting._ A marine boiler provided with furnaces and flue doors at each end, and therefore fired from each end.
DRY STEAL/11.0r SATURATED Steam which has not been superheated, nor mixed with the water of priming. It is the most suitable form of steam for use in engine cylinders.
An arrangement of pipes by means of which the feed-water for steam boilers is heated up to, or higher than, the boiling point.