Granted Patent
Utility
US 6,212,976 · App. 08/921,659
Duplex drill pipe wrench apparatus and method for top drilling rig drilling operations
Inventor:
Huey Stogner
Patented Case
View Patent ↗
Granted: Apr 10, 2001
Filed: Aug 28, 1997
Inventor
Huey Stogner
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.