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Product Description--Drill collars Drill Collars are one of the parts of a drill’s string. Drill for the Collars is meant to provide weight for drilling purposes. The Drill Collars are thick walled tube like pieces that are machined from solid steel bars, although they are often made from plain carbon steel or the non magnetic alloy of copper and steel or other premium alloys that are non magnetic in nature. Drill collar has bars of solid steel that are drilled from one end to the other to provide a passage for pumping the drilling fluids through the collar.
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Product Type
a. Cylindrical type drill collar: Be made of alloy steel and the cross sections of the inside and outside pipe are both round.
b. Spiral type drill collar：Be made of alloy steel and the outside pipe has spiral grooves.
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c. Non-magnetic type drill collar: Made of stainless alloy steel with rather low magnetic permeability and the cross sections of the inside and outside pipe are both round.
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Product connection features
1.API connections – All API connections(regular, NC, H90, and PAC) comply with dimensional requirements specified in API Spec. 7-2 .
2.Phosphate coating – All connections are phosphate-coated to improve resistance to galling
3.Stress relief features – API pin stress relief groove and API box boreback decrease the frequency of fatigue failures. These features increase connection flexibility and reduce high-stress concentrations that normally occur adjacent to the end of engaged threads. Stress-relief features are machined in compliance with API Spec. 7-2.
4.Cold rolling – Drill collar thread roots are cold-rolled. Cold rolling creates a compressive stress condition that increases fatigue life by minimizing crack initiation.
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