Drill collars
Drill Collars are manufactured from AISI 4145H or 36CrNiMo4 modified steel, and are supplied in the "as rolled" surface finish condition. Alternative surface finishes can be provided.
Trepanning and Heat treatment:
Drill collars are trepanned and drifted to API Spec 7. Full-length heat-treatment processes ensure that mechanical properties meet or exceed API Spec 7 requirements. A hardness range of 285-341, Brinell Hardness and Charpy gV h notch minimum impact strength of 40 ft-lb at 70OF are guaranteed one inch below the surface.
Connections NC23 NC26and NC31(2 3/8 IF and 2 7/8 IF) have a sufficient steel thickness for machining stress-relief grooves.
Drill collar material and process traceability are maintained from receipt of mill certified raw material to completion of all the manufacturing.
Serial numbers are stamped on bar.
Rigid Inspection Procedures:
We inspect all our drill collars to comply with API standards. These inspections include visual dimensional checks as well as ultrasonic inspections over the entire body of the drill collar.
Cold Rolling:
Drill collar thread roots, as well as elevator recess upper radii, are cold-rolled. Cold rolling creates a compressive recess upper radii stress condition that increases fatigue life by minimizing crack initiation.
Phosphate-coated or copper plating:
All connections are phosphate-coated or copper plating to improve resistance to galling.
Slip groove, elevator groove and size:
Our company offers optional slip and elevator recesses to improve handling efficiency and safety. The upper radius of the elevator recess is cold can be used together or separately. Unless otherwise specified, slip and elevator recesses are machined in compliance with API RP 7G guidelines.
Thread protectors:
Our company offers steel and cast steel and plastic steel thread protectors for its drill stem products.
| Standard size ,bores and connection for drill collar | |||||||
| Style of connection | OD | ID | Length mm |
Bevel diameter 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(23/8IF) | 88.9 | 3 1/2 | 38.1 | 1 1/2 | 9150 | 82.9 | 2.42:1 |
| NC31-41(27/8IF) | 104.8 | 4 1/8 | 50.8 | 2 | 9150 | 100.4 | 2.43:1 |
| NC35-47 | 120.7 | 4 3/4 | 50.8 | 2 | 9150 | 114.7 | 2.58:1 |
| NC3850(31/2IF) | 127.0 | 5 | 57.2 | 2 1/4 | 9150 | 121.0 | 2.38:1 |
| NC44-60 | 152.4 | 6 | 57.2 | 2 1/4 | 9150or9450 | 144.5 | 2.49:1 |
| NC44-62 | 158.8 | 6 1/4 | 57.2 | 2 1/4 | 9150or9450 | 149.2 | 2.91:1 |
| NC46-62(4IF) | 158.8 | 6 1/4 | 71.4 | 2 13/16 | 9150or9450 | 150.0 | 2.63:1 |
| NC46-65(4IF) | 165.1 | 6 1/2 | 57.2 | 2 1/4 | 9150or9450 | 154.8 | 2.76:1 |
| NC46-65(4IF) | 165.1 | 6 1/2 | 71.4 | 2 13/16 | 9150or9450 | 154.8 | 3.05:1 |
| NC46-67(4IF) | 171.4 | 6 3/4 | 57.2 | 2 1/4 | 9150or9450 | 159.5 | 3.18:1 |
| NC50-67(41/2IF) | 171.4 | 6 3/4 | 71.4 | 2 13/16 | 9150or9450 | 159.5 | 2.37:1 |
| NC50-70(41/2IF) | 177.8 | 7 | 57.2 | 2 1/4 | 9150or9450 | 164.7 | 2.54:1 |
| NC50-70(41/2IF) | 177.8 | 7 | 71.4 | 2 13/16 | 9150or9450 | 164.7 | 2.73:1 |
| NC50-72(41/2IF) | 184.2 | 7 1/4 | 71.4 | 2 13/16 | 9150or9450 | 169.5 | 3.12:1 |
| NC50-77 | 196.8 | 7 3/4 | 71.4 | 2 13/16 | 9150or9450 | 185.3 | 2.70:1 |
| NC50-80 | 203.2 | 8 | 71.4 | 2 13/16 | 9150or9450 | 190.1 | 3.02:1 |
| 6 5/8REG | 209.6 | 8 1/4 | 71.4 | 2 13/16 | 9150or9450 | 195.7 | 2.93:1 |
| NC61-90 | 228.6 | 9 | 71.4 | 2 13/16 | 9150or9450 | 212.7 | 3.17:1 |
| 7 5/8REG | 241.3 | 9 1/2 | 76.2 | 3 | 9150or9450 | 223.8 | 2.81:1 |
| NC70-97 | 247.6 | 9 3/4 | 76.2 | 3 | 9150or9450 | 232.6 | 2.57:1 |
| NC70-100 | 254.0 | 10 | 76.2 | 3 | 9150or9450 | 237.3 | 2.81:1 |
| 8 5/8REG | 279.4 | 11 | 76.2 | 3 | 9150or9450 | 266.7 | 2.84:1 |
| Mechanical Property | ||||||
| TTT | Yield strength 0.2Mpa | Tensile strength b Mpa | Elongation 4% | Hardness(Brinell) | IMPACT VALUE(CHAPPY-V) | |
| mm | in inch | |||||
| 79.4-171.4 | 3 1/8-6 3/4 | ≥ 758 | ≥ 965 | ≥ 13 | 285-341 | ≥ 54 |
| 177.8-279.4 | 7-11 | ≥ 689 | ≥ 930 | |||
| STRESS-RELIEF SIZES FOR CONNECTION | |||||
| Style of connection | Length of inner thread shoulder face to last thread scratch Lx 1.59mm |
Diameter of inner thread cylinder D +0.40,-0mm |
Taper of area behind inner thread cylinder 20.83mm/m | Diameter of outer thread groove D RG +0,-0.79mm | Length of alternative inner thread shoulder face to stress-relief groove L RG +0,-3.18mm |
| NC35 | 82.6 | 82.15 | 166.67 | 82.15 | 85.73 |
| NC38(3 1/2IF) | 88.9 | 88.11 | 166.67 | 89.30 | 92.08 |
| NC44 | 101.6 | 101.60 | 166.67 | 106.36 | 104.78 |
| NC46(4IF) | 101.6 | 106.76 | 166.67 | 109.93 | 104.78 |
| NC50(4 1/2IF) | 101.6 | 117.48 | 166.67 | 120.65 | 104.78 |
| NC56 | 114.3 | 121.84 | 250.00 | 134.14 | 117.48 |
| NC61 | 127.0 | 132.95 | 250.00 | 149.25 | 130.18 |
| NC70 | 139.7 | 152.00 | 250.00 | 171.05 | 142.88 |
| 6 5/8REG | 114.3 | 134.14 | 166.67 | 137.72 | 117.48 |
| 7 5/8REG | 120.7 | 133.35 | 250.00 | 162.72 | 123.83 |
| 8 5/8REG | 123.8 | 149.25 | 250.00 | 184.94 | 127.00 |
Order Instructions:
- Type (Slick or Spiral grooved)
- Outside and inside size and overall length
- Connection type and size
- API Stress relief Groove on pin and box ends
- Cast or pressed steel thread protectors
- Other special request, for example: slips or elevator recess and hardbanding style.
Non-MAGNETIC DRILL COLLARS
Materials of the Non-magnetic drill collars are made from chrome manganese, low C alloy obtained by combining a proprietary chemical analysis and a rotary hammer process. The material is resistant to stress corrosion cracking, with high machine ability and no tendency to galling.
Magnetic permeability (when MPS=1105/4Nm)
Relative max:1.010 average: U?? 1.005
Magnetic field gradient (hot spots)
Max: B 0.05micro tesla/100mm
The non-magnetic drill collars exhibit the mechanical properties indicated below along their entire length. The table is derived from test samples of steel taken from a point 1 below the surface.
| Mechanical Property | ||||
| OD | Yield strength 0.2 | Tensile strength b | Elongation 4(%) | |
| mm | in | |||
| 79.4--171.4 | 3 1/8--6 3/4 | ≥ 758 | ≥ 827 | ≥ 18 |
| 177.8--279.4 | 7--11 | ≥ 689 | ≥ 758 | ≥ 20 |
Non-magnetic Properties
- Relative Max: 1.010
- Average: ≤ 1.005
- Max. B ≤ 0.05 Micro Tesla/100 mm
Order Instructions
- Size of Non-magnetic Drill Collar
- Length
- Connection Type
- API Stress relief recess
- Other special request.
SPIRAL DRILL COLLAR
Spiral grooves let mud circulate freely around the drill collar to equalize pressure and prevent a seal from forming. The spiral drill collar reduces the occurrence of differential pressure sticking. Spiral prevents differential sticking without spiral.
Spiral collars are wide used because of their maintenance features. The special grooves decrease the volume of the contact between the well side and the pipe, it leads to the decrease of the "tack" of the pipe and to turning of the drill pipe string.
The weight of round drill collars will be reduced approximately 4-6% by spiral conversion.
