4.125 Inch 4.75 Inch Drill Collars
4.125 Inch 4.75 Inch Drill Collars
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Basic Infomation
Place of Origin: China
Brand Name: ROSCHEN
Certification: API
Model Number: 4.125inch 4.75inch
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drill collars


Non-Magnetic Drill Collars


Short nonmagnetic drill collars

Payment & Shipping Terms
Packaging Details: wooden Box, Bundle
Supply Ability: 20000sets/m
Product Description


Drill Collars 4.125inch 4.75inch



Non-Magnetic Drill Collars


Command Tubular’s non-magnetic drill collars are an integral heavy duty joint that are constructed from a solid bar of austenitic stainless steel. Our non-magnetic drill collars are supplied with a machined surface finish condition.


All non-magnetic collars are hot/cold worked in order to provide them with the necessary mechanical properties. The bars are then trepanned, hot spot inspected and machined. An internal bore treatment is performed on the full length in order to achieve the proper compressive status of the internal diameter.


This provides the collar with optimal resistance to stress corrosion cracking. All of our drill collars are manufactured in accordance with API spec 7, Q1 and recommended practice 7G as applicable.

4.125 Inch 4.75 Inch Drill Collars 0

4.125 Inch 4.75 Inch Drill Collars 1




Spiral Drill Collars


The spiral cut is added to a drill collar to prevent the likelihood of differential wall-sticking by reducing wall contact between the drill collar and the wall of the hole. The spiralling starts 22” from the bottom of the slip recess or 79” from the box end and ends 30” from the pin end. Adding spiralling to drill collars reduces the weight by approximately 4%.


Short nonmagnetic drill collars (SNMDCs):

SNMDCs are used between a mud motor and a mud collar to neutralize magnetic interference from the following.




All connections are precision-machined to API Spec 7-2 requirements. API relief groove pin and bore back box stress relief are available on request. Thread roots are cold-worked to offer a greater resistance to fatigue. At Command Tubular all connections are phosphate coated to minimize galling during makeup and thread storage compound is applied. Thread protectors are installed to ensure adequate joint protection during shipment.



Drill Collars in Drilling Application

Drill collars play a vital role in drilling process. Due to the structural features, drill collars can provide weight for drilling purpose, which is drill collar’s one and foremost specialty. Gravity works on a number of drill collars to offer enough downward force needed to break rocks with the drill bit.

Apart from providing weight on the bit (WOB), drill collars also work as a shock absorber to dampen the vibration and shaking when drilling takes place. In this way, the drilling process can be carried out in a much steadier state.

Thirdly, the presence of the drill collars allows the pipelines to stay in the tensile state, while guarantees the rigidity of the drill string under great compression. Thus, the drill efficiency and quality are greatly improved.

In addition to the above applications, drill collars can help to control the direction of the bottom hole assembly, avoiding the problem of hole deviation and enhancing the performance of drilling.



For more information please contact:



WeChat: +86-137 6419 5009 ; +86-135 8585 5390

WhatsApp: +86-137 6419 5009 ; +86-135 8585 5390

Email: roschen@roschen.com ; roschen@roschen.net


Website: http://www.roschen.com ; http://www.roschen.net

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Contact Person : Mr. Bill, George, Michael
Tel : 13764195009
Fax : 86-021-54380177
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