Granted Patent
Utility
US 6,554,247 · App. 09/849,819
Quick release blowout preventer bonnet
Inventors:
Michael Wayne Berckenhoff, Edward Hemphill
Patented Case
View Patent ↗
Granted: Apr 29, 2003
Filed: May 4, 2001
Inventors
Michael Wayne Berckenhoff
Edward Hemphill
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.