US PATENT SUBCLASS 175 / 71
.~.~ Gaseous fluid or under gas pressure

Current as of: June, 1999
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175 /   HD   BORING OR PENETRATING THE EARTH

57  DF  PROCESSES {5}
65  DF  .~ Boring with specific fluid {7}
71.~.~ Gaseous fluid or under gas pressure

DEFINITION

Classification: 175/71

(under subclass 65) Processes comprising (1) drilling with a gaseous fluid as the circulating drilling fluid or (2) the placing of a gas under pressure in the borehole during drilling either along or over a liquid drilling fluid.

SEE OR SEARCH THIS CLASS, SUBCLASS:

69, and the search there noted for combined liquid and gaseous supply.