Granted Patent
Utility
US 5,957,366 · App. 08/957,963
Helically formed welded pipe and diameter control
Inventor:
Ralph Friedrich
Patented Case
View Patent ↗
Granted: Sep 28, 1999
Filed: Oct 21, 1997
Inventor
Ralph Friedrich
Assignee (at issue)
AMERON INTERNATIONAL 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.