| Title | Age |
|---|---|
| pressure regulation | 10 years, 37 weeks and 2 days |
| volume measuring | 10 years, 37 weeks and 2 days |
| leakage detection and control | 10 years, 37 weeks and 2 days |
| construction and maintenence | 10 years, 37 weeks and 2 days |
| table engineering | 10 years, 37 weeks and 2 days |
| all-ions day | 10 years, 37 weeks and 2 days |
| GAS FLOW CALCULATIONS | 10 years, 37 weeks and 2 days |
| tempering load | 10 years, 37 weeks and 2 days |
| basic of science | 10 years, 37 weeks and 2 days |
| gas industry plan | 10 years, 37 weeks and 2 days |