(under the class definition) Subject matter relating to the structure of tubes and flues for boilers not of general application and their connection with the boiler and couplings for tubes or flues, not specially provided for in other subclasses.
SEE OR SEARCH THIS CLASS, SUBCLASS:
360+, and 365, for tube couplings for headers and drums and the structure of the headers and drums.
SEE OR SEARCH CLASS
110, Furnaces,
322+, for protecting devices for the ends of boiler tubes. 138, Pipes and Tubular Conduits, for tubes of general utility.
165, Heat Exchange,
177+, for a tubular structure of more general utility specialized to heat exchange.
285, Pipe Joints or Couplings,
189+, for couplings for tubes of boilers and condensers or feed-water heaters to the tube sheet.
