Overburden Drilling Method -
rotary percussion with hydraulic drifter rotary with DTH
The special application of rotary percussive drilling is drilling in ground conditions which can not be displaced like hard rock, rock banks, gravel or where a risk to create caverns is.
Overburden drilling systems base on Duplex casings. The flushing medium reaches the drill bit through a special flushing head and in the inner rods.
The flushing medium and drill cuttings are carried out through the ring space between the inner rod and the casing and leaves through openings in the flushing bell.
Rotary percussion drilling with DTH hammer is a modification of overburden drilling, where the flush is likewise carried to the DTH hammer through the inner rods and carried off the same way as in rotary percussion drilling.
For DTH drilling the internal rod is normally equipped with an API thread.
Overburden Drilling Method (mm / inch) |
| Ø 88,9 / 3,5 |
Ø 1 1/2" - T38 |
or Ø 51,0 / 2 |
| Ø 101,6 / 4 |
Ø 1 1/2" - T38 |
or Ø 63,5 / 2,5 |
| Ø 114,3 / 4,5 |
Ø 1 3/4" - T45 |
or Ø 76,1 / 3 |
| Ø 133,0 / 5,23 |
Ø 1 3/4" - T45 Ø 2 1/4" - T51 |
or Ø 88,9 / 3,5 |
| Ø 152,4 / 6 |
Ø 2 1.4" - T51 |
or Ø 101,6 / 4 |
| 177,8 / 7 |
|
Ø 114, 3 / 4,5 |
|
