Granted Patent
Utility
US 4,795,128 · App. 07/162,707
Gate type kelly cock valve
Inventors:
Igor Krasnov, Henry D. Calk, Jr., Taylor L. Jones, Billy L. McDougal
Patented Case
View Patent ↗
Granted: Jan 3, 1989
Filed: Mar 1, 1988
Inventors
Igor Krasnov
Henry D. Calk, Jr.
Taylor L. Jones
Billy L. McDougal
Assignee (at issue)
Vetco Gray, LLC
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.