Watertube, Header and Watertube Assembly, Boiler having the Assembly, and Method of Assembling Same

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 said header;
• each of said watertubes having an intermediate section and at least one end section, said end section of each of said watertubes being connected to said header;
• said intermediate section of each of said watertubes having a substantially constant outer diameter along its full length and being closely spaced to adjacent watertubes;
• and
• said end section of each of said watertubes having a transition that reduces the diameter of the watertube as it extends from said intermediate section to an outwardly-extending circumferential flange located on an opposite side of said transition relative to said intermediate section such that said flange extends from a reduced-diameter part of said end section.

A method of assembling a boiler, comprising:

• mounting an elongate hollow base header below a combustion chamber of the boiler and mounting an elongate hollow dome header above the combustion chamber of the boiler such that said base header and dome header extend parallel with one another;
• and
• providing only a linear, non-staggered array of sockets in each of the base and dome headers;
• providing a plurality of watertubes such that each of the watertubes includes an intermediate section of substantially constant outer diameter and opposite end sections, each of the end sections having a transition that reduces the outer diameter of the watertube as it extends from the intermediate section to an outward-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 end section of reduced diameter, each outward-extending circumferential flange has a peripheral outer edge of a predetermined diameter that closes matches the outer diameter of said intermediate section;
• and
• connecting the plurality of watertubes to the linear array of sockets of the base and dome headers such that the intermediate sections of the watertubes extends through the combustion chamber of the boiler closely-spaced to intermediate sections of adjacent watertubes.