Reasons for failure of trenchless drill pipe

1. Non excavation drill pipe cracked along male and female threads
1) The torque of the drill across the dip angle of the drill pipe
2) The curvature radius of the construction hole spans the small curvature radius of the drill pipe
3) When reaming (mainly when expanding the hole) or drilling a pilot hole for a long distance, the drill bit suddenly hits a hard object to produce a strong impact. The sudden increase of formation torque causes the drill pipe to break or twist.
4) The operator shall reasonably control the rotation speed and propulsion force when operating the drilling rig to avoid such conditions.
2. Cracking of trenchless drill pipe
1) The torque of the drill across the dip angle of the drill pipe
2) The curvature radius of the construction hole spans the small curvature radius of the drill pipe
3) When reaming (mainly when expanding holes) or drilling pilot holes for a long distance, the drill bit suddenly encounters a hard object and produces a strong impact force. The formation torque increases suddenly, causing the drill pipe to break or twist.
4) The material and thickness of the drill pipe body do not meet the technical specification requirements.
5) The surface of drill pipe body is severely scratched (crossing depth is 1mm, and it is in spiral shape)
6) The drill pipe has been used for too long, and its appearance is more harmful, close to or beyond the fatigue life.
3. Cracking or cracking of non excavation drill pipe conflict welded junction
1) Welding quality problems
2) The problems in Article 1 and Article 2 shall be handled in the same way.
4. Twist or distortion of drill pipe body
1) The thrust is too large and too strong when drilling the guide hole.
2) Curvature radius of guide hole is too small during construction
5. End face expansion of trenchless drill pipe box
1) The drill pipes of different buckle types, different manufacturers, and large differences between the old and the new are used together. When the drill pipes are connected, the tight distance exceeds the specification, and the female buckle is expanded.
2) The buckle type of the protective sub joint of the drill power head is inconsistent with that of the drill pipe, or the wear is too severe, and the tight distance tolerance is large.
3) The length cooperation between male and female ports is prohibited, and the double top of the main and auxiliary step surfaces of the joint cannot be realized
4) The radius of curvature of the hole spans the allowable radius of curvature of the drill pipe to form a female thread expansion