CONVECTIVE FIRE TUBE FOR STEEL HOT-WATER FLUE BOILER AND METHOD OF MANUFACTURE OF SUCH TUBE Russian patent published in 2006 - IPC F22B37/06 

FIELD: heat-power engineering.

SUBSTANCE: proposed fire tube consists of two sections of thick-walled and thin-walled tubes located concentrically. Inner surface of thick-walled tube is provided with multi-start grooves of spiral direction and outer surface of thick-walled tube has spiral projections forming air pockets together with inner surface of thin-walled tube. End sections of thick-walled tube along its length are provided with circular grooves and projections for separation of air pockets. Method of manufacture of fire tube is based on fitting the outer surface of thick-walled section on thin-walled tube at spaced relation, after which circular and multi-start spiral grooves and grooves in inner cavity of thick-walled tube are subjected to plastic deformation.

EFFECT: avoidance of low-temperature corrosion attack on gas duct metal.

3 cl, 2 dwg