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
E21B17/00
Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables;; Casings; Tubings
E21B17/00
Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables;; Casings; Tubings
E21B17/10
Wear protectors; Centralising devices; , e.g. stabilisers
E21B17/10
Wear protectors; Centralising devices; , e.g. stabilisers
E21B17/1014
Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well
E21B17/1014
Flexible or expansible centering means, e.g. with pistons pressing against the wall of the well