| Title | Age |
|---|---|
| pressure regulation | 9 years, 50 weeks and 1 day |
| volume measuring | 9 years, 50 weeks and 1 day |
| leakage detection and control | 9 years, 50 weeks and 1 day |
| construction and maintenence | 9 years, 50 weeks and 1 day |
| table engineering | 9 years, 50 weeks and 1 day |
| all-ions day | 9 years, 50 weeks and 1 day |
| GAS FLOW CALCULATIONS | 9 years, 50 weeks and 1 day |
| tempering load | 9 years, 50 weeks and 1 day |
| basic of science | 9 years, 50 weeks and 1 day |
| gas industry plan | 9 years, 50 weeks and 1 day |