Granted Patent
Utility
US 4,768,539 · App. 07/098,444
Pipeline safety valve
Inventor:
Ronald E. Pringle
Patented Case
View Patent ↗
Granted: Sep 6, 1988
Filed: Sep 18, 1987
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.