Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6626467 | Closure for secondary containment pipe | Joie L. Folkers, Ralph Friedrich | 2003-09-30 |
| 5725920 | Fiber-reinforced resin pipe having improved impact resistance | Ralph Friedrich, Duane G. Hemphill, Joie L. Folkers, Brian M. Francis | 1998-03-10 |