Subs
Subs for drill strings designed to interconnect the individual parts of the drill string or acceding to the instrument with different type and size tool-joint thread for drilling and servicing oil, gas and exploration wells.
Description
| No. | Name | The upper connection part | The lower connecting part | Type |
| 1 | Transition sub square | Square | Drill pipe | A or B |
| 2 | Transition sub of the drill pipe | Drill pipe | Drill pipe | A or B |
| 3 | The intermediate transition sub | Drill pipe | UBT | A or B |
| 4 | Transition sub UBT | UBT | UBT | A or B |
| 5 | Transition sub of the drill bit | UBT | Drill bit | A or B |
| 6 | Transitional swivel sub | The lower sub of the swivel | Square | C |
| 7 | A transitional sub for fishing tool | Square | Drill pipe | C |
| Drill pipe | Fishing tool | C |