US PATENT SUBCLASS 148 / 634
.~.~.~.~.~ Hydrogen

Current as of: June, 1999
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148 /   HD   METAL TREATMENT

95  DF  PROCESS OF MODIFYING OR MAINTAINING INTERNAL PHYSICAL STRUCTURE (I.E., MICROSTRUCTURE) OR CHEMICAL PROPERTIES OF METAL, PROCESS OF REACTIVE COATING OF METAL AND PROCESS OF CHEMICAL-HEAT REMOVING (E.G., FLAME-CUTTING, ETC.) OR BURNING OF METAL {17}
559  DF  .~ Heating or cooling of solid metal {22}
579  DF  .~.~ Iron(Fe) or iron base alloy {24}
625  DF  .~.~.~ Treating with specified agent (e.g., heat exchange agent, protective agent, decarburizing agent, denitriding agent, etc.) or vacuum {8}
633  DF  .~.~.~.~ Gaseous agent {2}
634.~.~.~.~.~ Hydrogen

DEFINITION

Classification: 148/634

Hydrogen:

(under subclass 633) Process wherein the gaseous treating agent contains molecular hydrogen gas and excluding air.

(1) Note. While water is excluded as a treating agent for this subclass, the presence of molecular hydrogen, as may be found in equilibrium in steam, is acceptable if the specification discloses the use thereof for molecular hydrogen content.

(2) Note. Although there is molecular hydrogen present in air, the mere use of air is not intended as proper for this subclass.