Issued Patents All Time
Showing 1–4 of 4 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5101863 | Rehabilitating underground pipes with expanding helically wound liner | Shigeki Fujii, Hirozo Hirayama, Masahisa Sonku | 1992-04-07 |
| 4951758 | Method of drilling a branch line aperture after internal lining of a pipeline and a water plug used in the method | Masahisa Sonku, Yukio Yoshimura, Naoki Kitahashi, Hirozo Hirayama, Harutoshi Miyazaki +1 more | 1990-08-28 |
| 4568373 | Soil amendment matters | Yoshinobu Yagyu | 1986-02-04 |
| 4200605 | Production of reinforced plastic pipes | Tetuo Imamura, Masaru Teramae | 1980-04-29 |