IPC Subgroup
E21B 4/2 combined with surface drive
Introduced: January 1980
Last revised: January 2006
Full Title
Drives for drilling, used in the borehole > combined with surface drive
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