| After-sales Service: | Online Services |
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| Warranty: | One Year |
| Certification: | API |
| Customization: |
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Shipping Cost:
Estimated freight per unit. |
about shipping cost and estimated delivery time. |
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| Payment Method: |
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| Initial Payment Full Payment |
| Currency: | US$ |
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| Return&refunds: | You can apply for a refund up to 30 days after receipt of the products. |
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Audited Supplier 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. 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.
Drill Collars are heavy and stiff steel tubular, and they are used at the bottom of a BHA to provide weight on bit. There are different kinds of DCs available such as flush or spiral DC. In directional drilling, spiral DCs are preferable because the spiral grooves reduce the wall contact area by 40% for a reduction of weight of only 4%. Hence, chances of differential sticking can be greatly minimized. There are other classifications of DCs as mentioned in the following.
Nonmagnetic drill collars: NMDCs are generally flush (nonspiral). They are manufactured from high-quality, corrosion-resistant, stainless steel. They are used while running the magnetic survey instruments to be located in a NMDC of sufficient length to allow the measurement of the earth's magnetic field without magnetic interference. Survey instruments are isolated from magnetic disturbance caused by other steel components in the BHA.
| 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 | 0.337 | 2.57:1 |
| NC 26-35 (2-3/8 IF) | 3-1/2 | 1-1/2 | 30 | 26.7 | 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 | 75.9 | 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 | 1.42 | 3.05:1 |
| NC 46-67 (4IF) | 6-3/4 | 2-1/4 | 30 or 31 | 108.52 | 1.6 | 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 | 139.9 | 2.14 | 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 | 3.319 | 2.81:1 |
| NC 70 -97 | 9-3/4 | 3 | 30 or 31 | 230 | 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 | 4.574 | 2.84:1 |
| Standard Features | API Boreback Box Connection | |||||
| API stress relieve groove pin connection | ||||||
| Cold Rolling Thread roots | ||||||
| Phosphate coated connections | ||||||
| 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 | ||||||
| Protection | Standard Pressed Steel Thread Protectors. Cast Steel Lifting Bail Thread Protectors upon request. | |||||
| 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. | ||||||
1) How can I place an order?
A: You can contact us by email about your order details, or place an order online.
2) How can I pay you?
A: After you confirm our PI, we will request you to pay. T/T and Western Union are the most usual ways we are using.
3) What's the order procedure?
A: First we discuss order details and production details by email or TM. Then we issue you a PI for your confirmation. You will be requested to do prepaid full payment or deposit before we go into production. After we get the deposit, we start to process the order. We usually need 15-25days if we don't have the items in stock. Before production has finished, we will contact you for shipment details, and the balance payment. After payment has been settled, we start to prepare the shipment for you.
4)How do you take care when your clients received defective products?
A: replacement. If there are some defective items, we usually credit them to our customer or replace them in the next shipment.
5)How do you check all the goods in the production line?
A: We have spot inspection and finished product inspection. We check the goods when they go into the next step production procedure
Suppliers with verified business licenses
Audited Supplier 
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