I. features of trenchless engineering
The trenchless project belongs to the high risk project, the drill pipe quality and the correct standard choice and the use, is guarantees the project to complete smoothly the important factor, but is not the only factor. Pre-construction preparations, such as rationality of design, on-site exploration, geology, surface analysis, quality of construction personnel, construction methods, performance and reliability of drilling RIGS, mud ratio and application, and configuration of construction equipment, are all important factors related to the success or failure of trenchless engineering.
Ii. Precautions for the use of drill pipe
1. Select the right type of drill pipe according to the torque, pushing and pulling force of the drill and the allowable minimum radius of curvature.
2. Avoid connecting the large diameter drill pipe with the small diameter drill pipe during construction (i.e., mix the size and size of drill pipe) to prevent the small drill pipe from being broken or deformed due to insufficient strength.
3. When clamping the drill pipe with vise, do not clamp the female buckle part of the female joint to prevent the female buckle from being clamped out of shape.
4. Pay attention to the pre-tightening force of the upper button should be controlled within 15MPa when installing the connecting drill pipe to prevent the unloading difficulty due to excessive pressure. Avoid using fire to bake the joint, reduce the mechanical properties of the joint, (especially the female joint) affect the service life. Unpretightened thread connection swing, according to the thread grinding tooth tip tip tip, side ridge, lead to thread damage goods produced sticky buckle phenomenon. The thread root of the male joint may be fatigue broken if the female joint is not pre-tightened and the female buckle step is not pressed tightly. Under the action of high-pressure liquid flow, the female joint is punctured and corroded, which is likely to lead to longitudinal crack of the female joint.
5. Pay attention to clean the male buckle and female buckle before installing the drill pipe, and wipe on the thread buckle oil (thread buckle oil can not be replaced by other waste oil, poor pressure oil) to prevent premature wear and tear of the male buckle and female buckle or damage.
6. Pay attention to clear the channel hole before installing the connecting pipe to prevent debris blocking the channel from causing the mud system to suppress pressure.
7. Be careful not to force up the button. The male buckle shall not impact the shoulder and thread of the female buckle, and the male and female joint shall be centered. Ensure the coaxiality of the shackle of the drill and the spindle of the power head.
8. Pay attention to check the wear condition of each part of the drill pipe, and find out the reason in time if abnormal wear occurs:
1) determine whether the drill pipe is scratched by sharp and hard material in the hole
2) please use carefully when the scratch marks on the drill pipe body are about 1mm deep and more than one spiral circle. Prevent the drill pipe from being broken during construction, causing greater loss.
9. Note that if the drill collar short collar type is damaged (wrong or badly worn), it should be replaced in time to avoid damaging the drill pipe thread.
10. Pay attention to hoisting and handling the drill pipe to avoid impact damage to the male buckle.
11. Pay attention to avoid mixing different button type of drill pipe, even if it is not produced by the same manufacturer of drill pipe also do not mix (because each manufacturer manufacturing drill pipe technical parameters, processing methods, props, mechanical equipment, processing of drill pipe tolerance, close distance will be different); The difference between the old and the new is too big, the degree of wear and tear is too big drill pipe also do not mix, to avoid causing construction risk.
12. If it is found that the drill pipe buckle type has local small range (about 1-2 buckle, buckle length of 10mm) damage, it should be repaired in time before use.
13. Use qualified zinc-based rib grease, butter is not suitable for use as thread thread oil. Insufficient thread grease causes high point of joint shoulder damage, easy to make thread connection "loose" and cause thread damage. Do not use thread grease or use unqualified thread grease, can make thread buckle surface agglutinate, produce agglutinate buckle phenomenon.
Third, the drill pipe may appear in the use of the fault
1. The drill pipe breaks along the male and female thread
2. Fracture of drill pipe body
3. Fracture or open welding of friction welding joints
4. The drill pipe body is bent or twisted
5. End face expansion of drill pipe master buckle
6. Deformation of end face of drill pipe master buckle
7. The drill pipe buckle is damaged
8. The surface damage of drill pipe male and female joint is serious
Iv. Causes and treatment methods of drill pipe faults
1, drill pipe along the male and female thread fracture
1) the torque of the drill rig exceeds the torque borne by the inclination Angle of the drill pipe
2) the radius of curvature of the construction hole exceeds the minimum radius of curvature of the drill pipe
3) when reaming (especially when expanding) or drilling guide holes for a long distance, the drill bit suddenly encounters hard objects and generates a strong impact force. Causes the torque to increase suddenly, causes the drill pipe to break or twist to break.
4) the operator should reasonably control the rotation speed and propulsion force when operating the drill to avoid this kind of situation.
2, drill pipe body fracture
1) the torque of the drill rig exceeds the torque borne by the inclination Angle of the drill pipe
2) the radius of curvature of the construction hole exceeds the minimum radius of curvature of the drill pipe
3) when reaming (especially when expanding) or drilling guide holes for a long distance, the drill bit suddenly encounters hard objects and generates a strong impact force. Causes the torque to increase suddenly, causes the drill pipe to break or twist to break.
4) the material and thickness of drill pipe body do not meet the requirements of technical specifications.
5) serious scratches on the surface of the drill pipe body (over 1mm in depth and in a spiral shape)
6) the service time of drill pipe is too long, the surface damage is more, close to or beyond the fatigue life.
3, drill pipe friction welding joint cracking or fracture
1) welding quality problems
2) the problems in article 1 and article 2 shall be dealt with in the same way.
4. The drill pipe body is bent or twisted
1) push too much and too hard when drilling the guide hole.
2) the curvature radius of the guide hole in construction is too small
5. The end face of the drill pipe master buckle expands
1) different buckle types, different manufacturers, the old and new difference between the big difference between the drill pipe mix, resulting in tight distance when the drill pipe connection exceeds the standard, the female buckle expansion buckle.
2) the buckle type of the protection nipple joint of the power head of the drilling machine is inconsistent with the buckle type of the drill pipe or the wear is too serious, and the tight distance tolerance is large.
3) the length of male and female orifices is not matched correctly, and the double top of the main and auxiliary step surface of the joint cannot be realized
4) the radius of curvature of the hole exceeds the allowable radius of curvature of the drill pipe, resulting in female buckle expansion
6. The end face of the drill pipe master buckle is deformed
1) clamp the slips of vise on the female mouth
2) when the torque is too large to remove the buckle, hammer or fire will cause deformation.
7, drill pipe buckle damage
1) unqualified thread thread thread oil is not used.
2) the surface of the thread buckle is not cleaned
8. The surface damage of drill pipe male and female joint is serious
1) the clamping and tempering hardness of vice slips is too high and it is injured by clamping and clamping of vice slips.
2) joint heat treatment, nitriding hardness or material problems.
3) the joint is hit by sledgehammer or roasted by fire due to the difficulty of shackle.
Avoid or replace as much as possible.
