Description
There are different kinds of drill collars,including round drill stop collar,spiral drill collar,non-magnetic drill collar,square drill collar and so on.Ordinary drill collar is the circular cross section, the center has a water hole,the wall thickness is larger,the nozzle is smaller, the weight of per unit length is greater than the size of drill pipe almost 4- 5 times .The majority of drill collar is thread processing directly on the pipe body , but some of them also use the replaced joint.
Elevator groove and slip groove made on box thread face of slick drill collar or spiral drill collar can be used as lifting sub
and safety slip when tripping out. The technical parameters for elevator groove and slip groove are as API Spec7-1. Hardbanding is optional at customers’ requests.
Drill collar sizes and weights:
| Design | O | D | ID | Length | Chamfer Diameter |
|---|---|---|---|---|---|
| in | mm | +1.6-0.0mm | +152.4mm | +0.4mm | |
| NC23-31 | 3 1/8 | 79.4 | 31.8 | 9.15 | 76.2 |
| NC26-35 | 3 1/2 | 88.9 | 38.1 | 9.15 | 82.9 |
| NC31-41 | 4 1/8 | 104.8 | 50.8 | 9.159.45 | 100.4 |
| NC35-47 | 4 3/4 | 120.7 | 50.8 | 9.159.45 | 114.7 |
| NC38-50 | 5 | 127.0 | 57.2 | 9.159.45 | 121.0 |
| NC44–60 | 6 | 152.4 | 57.2 | 9.159.45 | 144.5 |
| NC44–60 | 6 | 152.4 | 71.4 | 9.159.45 | 144.5 |
| NC44-62 | 6 1/4 | 158.8 | 57.2 | 9.159.45 | 149.2 |
| NC44-62 | 6 1/4 | 158.5 | 71.4 | 9.159.45 | 150.0 |
| NC46-65 | 6 1/2 | 165.1 | 57.2 | 9.159.45 | 154.8 |
| NC46-65 | 6 1/2 | 165.1 | 71.4 | 9.159.45 | 154.8 |
| NC46-67 | 6 3/4 | 171.5 | 57.2 | 9.159.45 | 159.5 |
| NC50-70 | 7 | 177.8 | 57.2 | 9.159.4 | 164.7 |
| NC50-70 | 7 | 177.8 | 71.4 | 9.159.45 | 164.7 |
| NC50-72 | 7 1/4 | 184.2 | 71.4 | 9.159.45 | 169.5 |
| NC56-77 | 7 3/4 | 196.9 | 71.4 | 9.159.45 | 185.3 |
| NC56-80 | 8 | 203.2 | 71.4 | 9.159.45 | 190.1 |
| 6 5.8REG | 8 1/4 | 209.6 | 71.4 | 9.159.45 | 195.7 |
| NC61-90 | 9 | 228.6 | 71.4 | 9.159.45 | 212.7 |
| 7 5/8REG | 9 1/2 | 241.3 | 76.2 | 9.159.45 | 223.8 |
| NC70-97 | 9 3/4 | 247.7 | 76.2 | 9.159.45 | 232.6 |
| NC70-100 | 10 | 254.0 | 76.2 | 9.159.45 | 237.3 |
| 8 5/8REGc | 11 | 279.4 | 76.2 | 9.159.45 | 266.7 |
