Granted Patent
Utility
US 4,647,002 · App. 06/783,252
Ram blowout preventer apparatus
Inventor:
Mark K. Crutchfield
Patented Case
View Patent ↗
Granted: Mar 3, 1987
Filed: Sep 30, 1985
Inventor
Mark K. Crutchfield
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.