Combined-interlock Kelly bar is composed of interlock Kelly bar and full multi-interlock Kelly bar.
For this type of Kelly bar , the first section is 3-keys interlock type, inner few sections are multi-type step keys , the outer keys are three- sections with three set of concave and convex form .
Specification
| No. |
Diammeter of The First Section
|
Sections | Key Pressure Type | Length of per section(m) | Drill depth | Torque(KN.M) | ||
| 1 | ¢440 | 3 | 4 | Interlocking | 9 - 15 | 24 – 55 | 220-260 | |
| 2 | ¢470(482) | 3 | 4 | Interlocking | 9 - 15 | 24 – 65 | 230-280 | |
| 3 | ¢508 | 3 | 4 | Interlocking | 9 – 15 | 24 – 70 | 260-360 | |
| 4 | ¢530(540) | 3 | 4 | 5 | Interlocking | 9 – 18 | 24 – 85 | 360-420 |
| 5 | ¢575(580) | 3 | 4 | 5 | Interlocking | 9 – 18 | 24 – 85 | 420-460 |
| 6 | ¢630 | 3 | 4 | 5 | Interlocking | 9 – 20 | 24 – 92 | 460-550 |
