(under subclass 373) Devices in which the means to facilitate the heat treatment includes apparatus for confining or directing a confined heated fluid or vapor about or into the vessel or a space in heat exchange relationship with the contents of the vessel or for shielding all or a portion of the contents from the action of the heated fluid.
SEE OR SEARCH THIS CLASS, SUBCLASS:
273+, for similar constructions in which there is a complete enclosure of the vessel.
390+, for heating surface construction and arrangement for vessels which are heated by an unconfined fluid.
