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Closed Circuit Circulation System-Double Wall Drill Pipe
Release time:
2019-11-04
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Introduction of Double Wall Drill Pipe
double wall drill pipeAlso known as double drill pipe. By the inner and outer two layers of drill pipe(Inner tube and outer tube)composed. The question between the inner and outer tubes constitutes an annulus.,It is hydraulic rock drilling and central sampling drilling.,A channel for pumping flushing medium to the bottom of the well. The central bore of the inner tube is discharged and the flushing medium is fixed into a whole,The connection between each double-walled drill pipe is made with the thread of the outer pipe.,Guaranteed transmission of torque and pressure. And the inner tube between the use of plug-in mode,Generally, it only plays the role of circulating flushing medium,Therefore,Sealing device shall be set at the plug joint.
Basic structure of double-wall drill pipe
Drill pipe for rotary table drive mainly has two types of square section and hexagonal section, Under the condition that the inner diameter and outer diameter have been determined, The hexagonal section has greater mechanical strength, Therefore, the drill rod for driving the double-walled pipe is determined to be a hexagonal cross-section.
The design of the double-wall drill pipe joint is focused on the buckle type of the outer pipe joint. Theoretically speaking, The greater the taper of the thread, The greater the external force the screw thread bears., The standard taper shall be selected when considering both the external force of the thread and the comprehensive bearing capacity of the joint., This is conducive to processing, Guaranteed quality. by calculating, Taper of screw thread is preliminarily determined1 :16, The pitch is4.2 mm, The tooth type is geological drill pipe buckle tooth type.
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