Watertube and method of making and assembling same within a boiler or heat exchanger

Abstract

A one-piece tube for use as a watertube within a watertube boiler or heat exchanger has a free end section that is formed to have an integral, outward-extending circumferential ring, or flange, a spaced distance from an adjacent end face of the tube. A boiler is provided that has an elongate header and a plurality of separate watertubes each having an intermediate section and opposite end sections. An end section of each watertube is connected to the header. The intermediate section of each watertube has a substantially constant outer diameter along its full length and is closely spaced to adjacent watertubes within the combustion chamber. At least one of the end sections of each watertube has a transition that reduces the diameter of the watertube as it extends from the intermediate section to an outwardly-extending circumferential flange. This arrangement permits close spacing of the connection sites of the watertubes to the header and permits the connection sites to be provided in a linear array.

1 . A watertube for use to conduct water or steam, the watertube comprising:
 an intermediate portion having a first end portion and a second end portion;   the first end portion having an integrally formed, radially outward-extending circumferential flange spaced from a free end of the first end portion, the flange formed to accept a driving force applied in a direction parallel to the longitudinal axis of the first end portion toward the free end of the first end portion without failing;   a radially extending surface on a distal side of the flange, the radially extending surface being dimensioned to engage an apparatus which exerts the driving force;   the first end portion having a tapered outer wall which tapers down from the flange to the free end of the first end portion;   whereby an axial force applied to the radially extending surface of the flange results in the tapered first end portion being received in an opening of a manifold and secured in fluid-tight engagement therein.   
   
   
       2 . The watertube as recited in  claim 1 , wherein the intermediate portion has a serpentine configuration. 
   
   
       3 . The watertube as recited in  claim 1 , wherein the first end section has been compressed along its axial length to form the flange. 
   
   
       4 . The watertube as recited in  claim 1 , wherein the tapered outer wall of the first end portion has a frustoconical configuration. 
   
   
       5 . The watertube as recited in  claim 1 , wherein a fastener is positioned on the flange to ensure that the first end portion of the watertube will be retained in the opening of the manifold. 
   
   
       6 . The watertube as recited in  claim 1 , wherein the flange is continuous about the circumference of the first end portion of the watertube. 
   
   
       7 . The watertube as recited in  claim 1 , wherein the tapered outer wall has a non-uniform, varying taper configuration. 
   
   
       8 . The watertube as recited in  claim 1 , the second end portion comprising:
 an integrally formed, radially outward-extending, circumferential second flange spaced from a free end of the second end portion, the second flange formed to accept a driving force applied in a direction parallel to the longitudinal axis of the second end portion in a direction toward the free end of the second end portion without failing;   a second radially-extending surface on a distal side of the second flange, the second radially-extending surface being dimensioned to engage an apparatus which exerts the driving force;   the second end portion having a tapered second outer wall which tapers down from the second flange to the free end of the second end portion;   whereby an axial force applied to the second radially-extending surface of the second flange results in the tapered second end portion being received in an opening of a manifold and secured in fluid-tight engagement therein.   
   
   
       9 . A boiler, comprising:
 an elongate header located adjacent the boiler;   a plurality of watertubes each having an intermediate section and an end section, the end section of each of the watertubes connecting to the header;   the intermediate section of each of the watertubes having a substantially constant outer diameter;   the end section of each of the watertubes having a transition that reduces the diameter of the watertube as it extends from the intermediate section; and   the end section of each of the watertubes having an outwardly-extending circumferential flange located on an opposite side of said transition from said intermediate section such that said flange extends from a part of said end section of reduced diameter.   
   
   
       10 . A boiler according to  claim 9 , wherein the outwardly-extending circumferential flange has a peripheral outer edge of a predetermined diameter that closely matches or is not significantly greater than the outer diameter of the intermediate section. 
   
   
       11 . A boiler according to  claim 9 , wherein the header has a series of sockets for receiving a portion of the end sections of the watertubes, and wherein the series of sockets of the header is provided solely as a closely-spaced, non-staggered, linear array of sockets. 
   
   
       12 . A boiler according to  claim 9 , wherein a fastener is secured to the header between each of said sockets and extends over and engages top surfaces of the outwardly-extending circumferential flanges of an adjacent pair of the watertubes to prevent withdrawal of the watertubes from the sockets. 
   
   
       13 . A boiler according to  claim 9 , wherein each of the watertubes are identical and made of a single length of tube with integral end sections having the transition and outwardly-extending circumferential flange formed by a forming operation. 
   
   
       14 . A boiler according to  claim 9 , wherein each of the watertubes are identical and include an end fitting welded thereto for providing the outwardly-extending circumferential flange. 
   
   
       15 . A boiler according to  claim 9 , wherein the watertubes each have a second end section which extends from the intermediate section, the second end section of each of the watertubes including said transition and said outwardly-extending circumferential flange. 
   
   
       16 . A boiler according to  claim 9 , wherein the intermediate section of each of the watertubes extends in a non-linear, serpentine path. 
   
   
       17 . A watertube and header assembly for a boiler or heat exchanger, comprising:
 an elongate, hollow header extending within the boiler or heat exchanger; and   a plurality of separate, closely-spaced, elongate watertubes extending from the header;   each of the watertubes having an intermediate section and at least one end section, the end section of each of the watertubes being connected to the header;   the intermediate section of each of the watertubes having a substantially constant outer diameter along its full length and being closely spaced to adjacent watertubes; and   the end section of each of the watertubes having a transition that reduces the diameter of the watertube as it extends from the intermediate section.   
   
   
       18 . A watertube and header assembly according to  claim 17 , wherein an outwardly-extending circumferential flange is located on an opposite side of the transition relative to the intermediate section such that the flange extends from a reduced-diameter part of the end section. 
   
   
       19 . A watertube and header assembly according to  claim 18 , wherein the outwardly-extending circumferential flange has a peripheral outer edge of a predetermined diameter that closely matches the outer diameter of the intermediate section. 
   
   
       20 . A watertube and boiler assembly according to  claim 19 , wherein the header has a series of sockets for receiving free end tip portions of the end sections of the watertubes, the series of sockets being provided as a closely-spaced linear array of sockets along a length of the header. 
   
   
       21 . A watertube and boiler according to  claim 20 , wherein a fastener is secured to the header between each of the sockets and extends over and engages upper surfaces of the outwardly-extending circumferential flanges of an adjacent pair of the watertubes to prevent withdrawal of the free end tip portions of the watertubes from the sockets. 
   
   
       22 . A watertube for a boiler or heat exchanger, comprising an intermediate section and opposite end sections, the intermediate section having a substantially constant outer diameter along its full length and having bends providing the intermediate section with a serpentine-like shape, each of the opposite end sections having a transition that reduces the diameter of the watertube as it extends from the intermediate section to an outwardly-extending circumferential flange located on an opposite side of the transition relative to the intermediate section such that the flange extends from a part of the section of reduced diameter, the outward-extending circumferential flanges having a peripheral outer edge of a predetermined diameter that closely matches the outer diameter of the intermediate section. 
   
   
       23 . A watertube according to  claim 22 , wherein the transitions and outwardly-extending circumferential flanges are integral, formed parts of the watertube. 
   
   
       24 . A watertube according to  claim 22 , wherein the outwardly-extending circumferential flanges are provided by separately-manufactured end fittings that are welded to the end sections.