1. Failure Across Female Threads

Probable causes:

-Hole deviation or drill string misalignment

-Insufficient feed pressure

-Excessive torque due to use of worn drill bits

-Mismatched threads

-Dents or deformations on the steel surface

Suggested actions:

-Use guide tools and bits designed with a drop center face or retract body

-Adjust feed pressure based on the rock conditions

-Sharpen dull carbide tips on the bit in accordance with recognized sharpening processes

-Avoid mixing drill string components from different manufacturers

-Use proper wrenches for loosening joints

-Avoid hitting outside the area of the joint

2. Deformation of female end

 Probable causes:

-Drilling with loose thread connections

-Misalignment during the threading of drill rods, resulting in impacts against the coupling shoulder

Suggested actions:

-Ensure thread connections are securely tightened prior to beginning percussion drilling

-Align drill rods correctly before threading them together

3. Vertical crack on the female end

Probable causes:

-Hole deviation

-Worn-out thread condition

-Misalignment when assembling drill rods

-Drilling with loose thread joints

Suggested actions:

-Focus on drilling more straighter holes

-Replace worn out components of the drill string in time

-Ensure tightness of joints before starting to drill

-Align drill rods correctly prior to threading

4.  Pitting or Wear in Threads

Probable causes:

-Overheating of threads due to loose connection or hole deviation

-Reflected percussive energy

-Dry firing or free hammering

-Drilling of worn-out bits

Suggested actions:

-Initiate percussion only when the bit is correctly engaged with the rock

-Sharpen dull carbides on the bit following appropriate procedures

-Replace worn-out drill string parts; avoid coupling worn bits or rods with new ones

-Fine-tune percussion and feed pressure based on drilling conditions

-Employ proper type and adequate lubrication, check often

5. Failure at The Beginning of the Thread

   Probable causes:

-Worn threads

-Bending from feed overpressure, or misalignment

-High rotational forces from using a worn bit resulting in high energy feedback

-Poor drilling conditions or unstable rock formations

-Persisting percussion with a stuck rod

-Bending due to poor alignment

Suggested actions:

-Replace worn drilling components; ensure changes of couplings and rods are done simultaneously

-Adjust feed pressure to prevent drill string bending

-Follow proper sharpening methods for dull carbides

-Optimize drilling parameters suitable to the rock conditions

-Use bits featuring a drop center face or retract body

-Avoid engaging percussion with a stuck drill string

6. Male end broken at face

  Probable causes:

-Insufficient feed pressure

-Use of dull drill bits

-Worn threads on couplings or bits

-Misalignment when connecting drill rods

-Corrosion-induced fatigue failure

Suggested actions:

-Replace worn-out components; never mount a worn coupling on a new rod

-Timely maintenance of button bits

-Set feed pressure according to the rock conditions

-Ensure proper alignment during rod threading

-Use extensions to better align drilling components

7.  Inner surface compromised

  Probable causes:

-Corrosive damage from flushing agents

-Insufficient rust protection

-Presence of pores on flushing hole surfaces

Suggested actions:

-Maintain or replace flushing agents as necessary

-Implement appropriate storage methods

-Change out components with higher frequency

8. Outer surface compromised

 Probable causes:

-Bending from misalignment

-Excessive feeding pressure

-External damage from the rod rubbing against steel surfaces

-Improper handling and care

-Challenging drilling conditions

-Hammer strikes

Suggested actions:

-Ensure regular maintenance of the drilling rig

-Verify the good condition of centralizers

-Use alignment tools and enhance drilling practices for straighter drilling; consider bits with drop center face designs or retractable bodies

-Adjust feed pressure according to rock conditions

-Avoid striking the drill rod from outside; employ suitable wrenches for loosening joints

-Store rods on racks rather than on the ground;

-Adjust drilling parameters to rock conditions