IPC Subgroup
E21B 21/1 Valves arrangements in drilling-fluid circulation systems
Introduced: January 1980
Last revised: January 2006
Full Title
Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor > Valves arrangements in drilling-fluid circulation systems
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS