Granted Patent
Utility
US 5,139,404 · App. 07/681,930
Apparatus for making lined pipe
Inventor:
Thomas D. Grau
Patented Case
View Patent ↗
Granted: Aug 18, 1992
Filed: Apr 8, 1991
Inventor
Thomas D. Grau
Assignee (at issue)
International Pipe Machinery Corporation
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.