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.

IPC Classes  ?

• F22B 37/12 - Forms of water tubes, e.g. of varying cross-section
• F22B 37/10 - Water tubesAccessories therefor
• F22B 37/20 - Supporting arrangements, e.g. for securing water-tube sets
• F28F 1/00 - Tubular elementsAssemblies of tubular elements
• F28F 9/12 - Arrangements for sealing elements into header boxes or end plates by dismountable joints by flange-type connections
• F24H 1/41 - Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water tube or tubes in serpentine form
• F24H 9/14 - Arrangements for connecting different sections, e.g. in water heaters
• B21D 39/06 - Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by platingTube expanders of tubes in openings, e.g. rolling-in