Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4969671 | Gas-tight joint for pipe linings and risers | Heinz Gross, Friedrich-Otto Koch, Matthias Lang, Hans Spliethoff, Wolfgang Venema +2 more | 1990-11-13 |
| 4823847 | Multi-layer helical seam steel pipe | Heinz Grosse, Friedrich-Otto Koch, Werner Wennemann | 1989-04-25 |
| 4721536 | Method for making steel tubes or pipes of increased acidic gas resistance | Heinz Grob, Friedrich-Otto Koch, Werner Wennemann | 1988-01-26 |
| 4688319 | Multi-layer helical seam steel pipe | Heinz Gross, Friedrich-Otto Koch, Werner Wennemann | 1987-08-25 |