Granted Patent
Utility
US 4,641,708 · App. 06/773,397
Casing hanger locking device
Inventor:
William David Wightman
Patented Case
View Patent ↗
Granted: Feb 10, 1987
Filed: Sep 6, 1985
Inventor
William David Wightman
Assignee (at issue)
Hughes Tool Company LLC
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.