Granted Patent
Utility
US 4,605,195 · App. 06/729,179
Annular blowout preventer packing unit
Inventors:
James A. Burton, Kenneth W. Colvin, Julian D. Keithahn
Patented Case
View Patent ↗
Granted: Aug 12, 1986
Filed: May 1, 1985
Inventors
James A. Burton
Kenneth W. Colvin
Julian D. Keithahn
Assignee (at issue)
Hydril Company
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.