Granted Patent
Utility
US 4,333,530 · App. 05/967,791
Method and apparatus for cementing a casing
Inventor:
Ernest E. Armstrong
Patented Case
View Patent ↗
Granted: Jun 8, 1982
Filed: Dec 8, 1978
Inventor
Ernest E. Armstrong
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.