The drill collar are made of 4145H modified chromium-molybdenum alloy steel according to API Spec 7 and aSY/T 5144 . All threads can be phosphated,copperised or cold worked. All threads are machined with CNC Lathes-Double-Shouldered and a special thread, the max diameter of drill collar is 14 inch.
Connection #OD
ID
L mm
DF
mm
Bending strength ratio
mm
in
Mm
In
NC23-31
79.4
3 1/8
31.8
1 1/4
9150
76.2
2.57:1
NC26-35
88.9
3 1/2
38.1
1 1/2
9150
82.9
2.42:1
NC31-41
104.8
4 1/8
50.8
2
9150 or 9450
100.4
2.43:1
NC35-47
120.7
4 3/4
50.8
2
9150 or 9450
114.7
2.58:1
NC38-50
127.0
5
57.2
2 1/4
9150 or 9450
121.0
2.38:1
NC44-60
152.4
6
57.2
2 1/4
9150 or 9450
144.5
2.49:1
NC44-60
152.4
6
71.4
2 13/16
9150 or 9450
144.5
2.84:1
NC44-62
158.8
6 1/4
57.2
2 1/4
9150 or 9450
149.2
2.91:1
NC46-62
158.8
6 1/4
71.4
2 13/16
9150 or 9450
150.0
2.63:1
NC46-65
165.1
6 1/2
57.2
2 1/4
9150 or 9450
154.8
2.76:1
NC46-65
165.1
6 1/2
71.4
2 13/16
9150 or 9450
154.8
3.05:1
NC46-47
171.4
6 3/4
57.2
2 1/4
9150 or 9450
159.5
3.18:1
NC50-67
171.4
6 3/4
71.4
2 13/16
9150 or 9450
159.5
2.37:1
NC50-70
177.8
7
57.2
2 1/4
9150 or 9450
164.7
2.54:1
NC50-70
177.8
7
71.4
2 13/16
9150 or 9450
164.7
2.73:1
NC50-72
184.2
7 1/4
71.4
2 13/16
9150 or 9450
169.5
3.12:1
NC56-77
196.8
7 3/4
71.4
2 13/16
9150 or 9450
185.3
2.70:1
NC56-80
203.2
8
71.4
2 13/16
9150 or 9450
190.1
3.02:1
6 5/8 REG
209.6
8 1/4
71.4
2 13/16
9150 or 9450
195.7
2.93:1
NC61-90
228.6
9
71.4
2 13/16
9150 or 9450
212.7
3.17:1
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