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What Are The Factors That Lead To The Failure Of The Drill Pipe(Pneumatic DTH Drilling Rig)? Mar 13, 2018

The factors leading to the failure of the drill pipe:

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The drill pipe of Pneumatic DTH Drilling Rig is an elongated elastic bar with its inherent vibration frequency, and the assembly of the drill string determines the natural frequency.When the drill pipe is rotated, there are three forms of vibration, which are longitudinal, transverse and torsional, which are resonant when their frequencies coincide with the natural frequencies.The result of resonance will attach an additional fatigue stress on the basis of the fatigue stress of the original drill pipe, and accelerate the failure of the drill pipe.It can be used to reduce the rotary bending fatigue of the drill pipe by using the long - acting screw drilling rod instead of rotary drilling directional well and horizontal well drilling.

The drill pipe works in the long and narrow well of drilling fluid inside and outside, usually withstanding the load of pressure, bending, twisting and hydraulic force.If the stress of the drill pipe is less than 206.8 newtons per square meter, the drill pipe will not produce fatigue cracks after numerous bending.When the drilling of drill pipe bending, torsion and tensile stress under complex stress is very big, especially in the large displacement torque of directional well and horizontal well is great, drill pipe is in far less than 1 million micro cracks bending fatigue occurs number;

After micro crack expanding extension, if have corrosion effect of high pressure fluid into micro cracks, will accelerate the crack propagation, eventually lead to drilling fluid puncture drill pipe failure accidents.The result of puncture development makes the effective section of the drill pipe shrink continuously, and the total length of puncture and crack is bigger than the critical crack size, which is the fracture.In addition to rotating downward motion, there are also various vibration and eddy motion of the drill pipe.

With the depletion of shallow resources, more and more drilling deep Wells and ultra-deep Wells in the future, the safety and reliability of drill pipe becomes a very prominent problem.The analysis of the failure reason of the drill pipe is good enough, and it is believed that there will be better help for the use!