Drill collars are heavy drill string members used as weight thus forcing the bit to penetrate the formation being drilled. The collars are made from selected bars of chromium molybdenum alloy steel AISI 4145 H bored by trepanning to ensure close tolerance of bore alignment. All drill collars are full length heat trated to obtain the best physical properties and to provide a combination of hardness strength and ductility.
|
Dimension |
Diam. ext. (mm.) |
Diam. Int. (mm.) |
Weight Kg./m. |
|
4 |
101 |
45 |
51 |
|
4 1/2 |
114 |
45 |
68 |
|
5 |
127 |
50 |
82 |
|
6 |
152 |
71 |
113 |
|
6 1/2 |
165 |
71 |
137 |
|
7 |
178 |
71 |
163 |
|
8 |
203 |
71 |
223 |
|
8 1/2 |
216 |
71 |
250 |
|
9 |
225 |
71 |
290 |
