DIFF Main Group
E21B 34/00 Valve arrangements for boreholes or wells
Introduced: January 1980
IPC and CPC are identically structured here. All 3 subcodes exist in both systems.
IPC defines codes here since 1980.
Child Classifications
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- E21B 34/16 Control means therefor being outside the borehole since 1980 IPC+CPC Available in IPC and CPC