Granted Patent
Utility
US 4,574,889 · App. 06/710,642
Method and apparatus for locking a subsurface safety valve in the open position
Inventor:
Ronald E. Pringle
Patented Case
View Patent ↗
Granted: Mar 11, 1986
Filed: Mar 11, 1985
Inventor
Ronald E. Pringle
Assignee (at issue)
Camco Inc.
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.