Granted Patent
Utility
US 4,572,298 · App. 06/549,255
Gate valve apparatus and method
Inventor:
Harry T. Weston
Patented Case
View Patent ↗
Granted: Feb 25, 1986
Filed: Nov 4, 1983
Inventor
Harry T. Weston
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.