Drill collars are extra-heavy integral tools used to concentrate weight onto the drill bit so as to produce sufficient force for the drill bit to break rock efficiently while drilling. They are made of AISI 4145H modified steel and are connected between drill pipes and drill bits.
Drill collars come in 30 or 31 foot lengths and are furnished as slick (as-rolled surface finish) or spiraled. Spiraled drill collars have grooves on its external surface which maintains an even flow of drilling fluid around the collar to equalize pressure and reduce differential-sticking of the collar to the wall of the oilwell.
Our drill collar connections comply with dimensional requirements specified in API Spec. 7/7-1 and guidelines presented in API RP7G. Drill collars also come with slip and elevator recesses for safe and efficient handling. Slip and elevator recesses can be used together or separately and are machined in compliance with API RP7G guidelines unless otherwise specified.
Common drill collar sizes are shown in the table below.
Products are manufactured to API Spec. 7/7-1 and API RP7G where applicable and can come customized with additional features and proprietary connections of leading manufacturers per your requirements.
We also offer Pony Collars and Non-Magnetic Drill Collars.
Contact us to discuss your requirements.
| Drill Collar Connection | Drill Collar Diameter(in) | Bore Diameter(in) | Length(ft) | Linear Weight (Approx.) (lb/ft) | Displacement (Open End) (US gal/ft) | Bending Strength Ratio |
| NC 23-31 | 3-1/8 | 1-1/4 | 30 | 22.00 | 0.337 | 2.57:1 |
| NC 26-35 (2-3/8 IF) | 3-1/2 | 1-1/2 | 30 | 26.70 | 0.408 | 2.42:1 |
| NC 31-41 (2-7/8 IF) | 4-1/8 | 2 | 30 or 31 | 33.65 | 0.515 | 2.43:1 |
| NC35-47 | 4-3/4 | 2 | 30 or 31 | 46.81 | 0.716 | 2.58:1 |
| NC 38-50 (3-1/2 IF) | 5 | 2-1/4 | 30 or 31 | 53.29 | 0.815 | 2.38:1 |
| NC 44-60 | 6 | 2-1/4 | 30 or 31 | 82.61 | 1.264 | 2.49:1 |
| NC 44-60 | 6 | 2-13/16 | 30 or 31 | 75.90 | 1.161 | 2.84:1 |
| NC 44-62 | 6-1/4 | 2-1/4 | 30 or 31 | 90.52 | 1.385 | 2.91:1 |
| NC 46 -62 (4IF) | 6-1/4 | 2-13/16 | 30 or 31 | 83.81 | 1.282 | 2.63:1 |
| NC 46 -65 (4IF) | 6-1/2 | 2-1/4 | 30 or 31 | 99.52 | 1.522 | 2.76:1 |
| NC 46-65 (4IF) | 6-1/2 | 2-13/16 | 30 or 31 | 92.81 | 1.420 | 3.05:1 |
| NC 46-67 (4IF) | 6-3/4 | 2-1/4 | 30 or 31 | 108.52 | 1.600 | 3.18:1 |
| NC 50-70 (4IF) | 7 | 2-1/4 | 30 or 31 | 117.52 | 1.798 | 2.54:1 |
| NC 50 -70 (4IF) | 7 | 2-13/16 | 30 or 31 | 110.77 | 1.694 | 2.73:1 |
| NC 50-72 (4IF) | 7-1/4 | 2-13/16 | 30 or 31 | 119.81 | 1.833 | 3.12:1 |
| NC 56-77 | 7-3/4 | 2-13/16 | 30 or 31 | 139.90 | 2.140 | 2.70:1 |
| NC 56-80 | 8 | 2-13/16 | 30 or 31 | 150.81 | 2.307 | 3.02:1 |
| 6-5/8 REG | 8-1/4 | 2-13/16 | 30 or 31 | 161.81 | 2.472 | 2.93:1 |
| NC 61-90 | 9 | 2-13/16 | 30 or 31 | 195.81 | 2.995 | 3.17:1 |
| 7-5/8 REG | 9-1/2 | 3 | 30 or 31 | 217.00 | 3.319 | 2.81:1 |
| NC 70 -97 | 9-3/4 | 3 | 30 or 31 | 230.00 | 3.518 | 2.57:1 |
| NC 70-100 | 10 | 3 | 30 or 31 | 242.97 | 3.717 | 2.81:1 |
| 8-5/8 REG | 11 | 3 | 30 or 31 | 299.00 | 4.574 | 2.84:1 |
| Standard Features |
API Boreback Box Connection API stress relieve groove pin connection Cold Rolling Thread roots Phosphate coated connections |
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| Options |
Spiral grooved or Non-Spiral (Slick Type) Type of Hardband and Hardband configuration Elevator and Slip recesses or Slip Recess only Other type of connections to meet specific needs |
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| Protection |
Standard Pressed Steel Thread Protectors. Cast Steel Lifting Bail Thread Protectors upon request. |
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| Mill Test Certificates |
Issued in accordance with API 7/7-1 and API RP7G specifications. Third Party Inspection can be performed on request at buyer’s care and expense. |
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