(under subclass 235) Subject matter comprising the structure of drums and couplings and unions between the drum and the header or the drum and the water tubes.
SEE OR SEARCH THIS CLASS, SUBCLASS:
192, for drums.
363, for headers of drum form.
393, for structure of mud drums unless of general application.
434, for special combinations of drums and feed water heaters. 511, and 512, for couplings of specific form for boilers.
