Granted Patent
Utility
US 6,520,253 · App. 09/848,647
Rotating drilling head system with static seals
Inventor:
Ian Calder
Patented Case
View Patent ↗
Granted: Feb 18, 2003
Filed: May 3, 2001
Inventor
Ian Calder
Assignee (at issue)
ABB Vetco Gray 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.