Granted Patent
Utility
US 6,766,570 · App. 10/041,221
Coupling units connecting tubular members having a hardened inner wall for carrying mechanically abrasive fluid concrete
Inventors:
Robert E. Klemm, Gary D. Lehnhardt
Patented Case
View Patent ↗
Granted: Jul 27, 2004
Filed: Jan 8, 2002
Inventors
Robert E. Klemm
Gary D. Lehnhardt
Assignee (at issue)
Construction Forms, 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.