Granted Patent
Utility
US 4,771,828 · App. 07/044,416
Wellhead seals
Inventor:
Thomas G. Cassity
Patented Case
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Granted: Sep 20, 1988
Filed: Apr 30, 1987
Inventor
Thomas G. Cassity
Assignee (at issue)
Cameron Iron Works USA, 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.