Granted Patent
Utility
US 4,979,562 · App. 07/261,385
Float equipment including float collars and modular plugs for well operations
Inventor:
Friedrich H. Langer
Patented Case
View Patent ↗
Granted: Dec 25, 1990
Filed: Oct 21, 1988
Inventor
Friedrich H. Langer
Assignee (at issue)
Weatherford Holding U.S., 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.