Granted Patent
Utility
US 5,364,064 · App. 08/213,623
Safety sub with asymmetrical wall elastomeric closure for retaining drilling fluids
Inventors:
Douglas W. Carlson, Stephen P. Simons
Patented Case
View Patent ↗
Granted: Nov 15, 1994
Filed: Mar 15, 1994
Inventors
Douglas W. Carlson
Stephen P. Simons
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.