Individual holder
GRAYBEAL WALTER C
US·3 granted patents·63 citations·filing 1976–1990
Individually held — no corporate assignee on record.
Top patents by PatentIndex Score
3 records- 0173US4030851AManhole closure including a two-way pressure relief valveGRAYBEAL WALTER C·Filed 1976·Granted Jun 21, 1977·29 cites·9 claims
- 0267US4512492AManhole closure with a single liquid impervious, two-way gas pressure relief valveGRAYBEAL WALTER C·Filed 1983·Granted Apr 23, 1985·29 cites·5 claims
- 0327US5033310AManhole cover inflow test deviceGRAYBEAL WALTER C·Filed 1990·Granted Jul 23, 1991·5 cites·8 claims
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Counts cover granted patents and pending applications in the PatentIndex corpus. How scoring works →