Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5180253 | Arrangement of prestressing tendons in a pressure tunnel | Erwin Siegfried | 1993-01-19 |
| 5066167 | Prestressed concrete lining in a pressure tunnel | Erwin Siegfried | 1991-11-19 |