E
FIXED CONSTRUCTIONS
E
FIXED CONSTRUCTIONS
E21
EARTH OR ROCK DRILLING; MINING
E21
EARTH OR ROCK DRILLING; MINING
E21B
EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
E21B
EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
E21B21/00
Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
E21B21/00
Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
E21B21/003
Means for stopping loss of drilling fluid
E21B21/003
Means for stopping loss of drilling fluid