Granted Patent
Utility
US 4,592,558 · App. 06/661,687
Spring ring and hat ring seal
Inventor:
John F. Hopkins
Patented Case
View Patent ↗
Granted: Jun 3, 1986
Filed: Oct 17, 1984
Inventor
John F. Hopkins
Assignee (at issue)
Hydril Company
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.