Patent classifications
E
FIXED CONSTRUCTIONS
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E21
EARTH OR ROCK DRILLING; MINING
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E21B
EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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25/00
Apparatus for obtaining or removing undisturbed cores, e.g. core barrels or core extractors
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E21B25/02
the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe
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