Causes and Solutions for Difficulty Disassembling Drill Pipe of Horizontal Directional Drill

In the process of backdragging and reaming of Horizontal Directional Drill, it often occurs that the drill pipe is difficult to disassemble, which leads to the delay of construction period. So what are the causes and solutions for the difficult disassembly of drill pipe?

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Causes

Drill pipe drilling angle deviation

In the preparatory stage, the operator failed to adjust the Angle of the drill frame in a timely and accurate manner, resulting in the deviation of the Angle of penetration between the body of the drill rig and the drill pipe, resulting in the difference of the center between the front and rear vice bodies and the drill pipe held. In the process of drilling and towing, abnormal force on the connection thread of drill pipe causes abnormal damage of the connection thread.

Fast drilling

During the construction process, the drilling and pulling back speed of the drilling rig is too fast, which increases the rotational pressure of the drill pipe and the rotational torque of the drill pipe beyond the maximum rotational torque, resulting in abnormal damage to the connecting thread of the drill pipe.

Poor quality drill pipe

Check the drill pipes that are difficult to disassemble at the construction site. If the connecting threads of these drill pipes are damaged and deformed, it means that the strength of the connecting threads of the drill pipes is not enough.

 

Solutions

Correct selection of drill pipe

When configuring the drill pipe for the directional drilling rig, the drill pipe should be selected reasonably according to the soil conditions, and the rotational torque of the drill pipe should be strictly controlled.

 

Operate the machine correctly

During the pipeline drilling / pullback construction of the drilling rig, the propulsion speed of the power head should be appropriately slowed down.

Operators should be trained to avoid excessive rotary torque of drilling rig due to ignorance of drilling rig and construction geology, resulting in damage and deformation of drill pipe connection threads.

Drill pipe disassembly method

When disassembling the drill pipe, first use the vice for routine disassembly. After holding 2 ~ 4 drill pipes in the vice, check whether the teeth are worn. If worn, replace the teeth in time.

When the drill pipe is particularly difficult to disassemble, the vise clamps the drill pipe more than 2 times, and the surface of the drill pipe clamping part is worn too much, the disassembly should be stopped immediately. Use oxygen acetylene flame to bake the threaded connection part of the drill pipe, or use a hammer to vibrate the threaded connection part of the drill pipe to disassemble.

If the drill pipe cannot be disassembled by the above method, only the pressure relief method can be used. The specific method is: use gas cutting to cut a triangular incision on the inner thread end of the drill pipe to release the tightening force, and then the drill pipe can be disassembled. However, due to the high price of the drill pipe, the cut-out pressure relief method can make it difficult to repair the cut drill pipe, so this method should be used with caution.

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Post time: Jul-05-2022