DIFF Subgroup
E21B 17/20 Flexible or articulated drilling pipes
Introduced: January 1980
Full Title
Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Casings; Tubings > Flexible or articulated drilling pipes
Of 2 combined children, 0 exist in both systems.
2 codes are CPC-only extensions.
Child Classifications
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