Granted Patent
Utility
US 4,640,732 · App. 06/837,755
Apparatus for fusion joining of thermoplastic pipes
Inventor:
Trevor G. Stafford
Patented Case
View Patent ↗
Granted: Feb 3, 1987
Filed: Mar 10, 1986
Inventor
Trevor G. Stafford
Assignee (at issue)
British Gas
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.