Granted Patent
Utility
US 4,958,770 · App. 07/346,637
Process for making uniform porosity flexible irrigation pipe
Inventor:
William S. Mitchell
Patented Case
View Patent ↗
Granted: Sep 25, 1990
Filed: May 3, 1989
Inventor
William S. Mitchell
Assignee (at issue)
Prescision Porous Pipe, Inc.
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.