Granted Patent
Utility
US 4,552,219 · App. 06/539,333
Subsurface safety valve
Inventors:
Fred Wong, Larry F. Grohman
Patented Case
View Patent ↗
Granted: Nov 12, 1985
Filed: Oct 5, 1983
Inventors
Fred Wong
Larry F. Grohman
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.