Granted Patent
Utility
US 6,644,411 · App. 09/837,097
Tubing hanger with flapper valve
Inventors:
Dewey Craig Compton, Edwin R. Knerr
Patented Case
View Patent ↗
Granted: Nov 11, 2003
Filed: Apr 18, 2001
Inventors
Dewey Craig Compton
Edwin R. Knerr
Assignee (at issue)
Kvaerner Oilfield Products A.S.
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.