SPECIAL FEATURES FOR DRILL COLLAR.

Spiral Grooving 

In order to reduce differential pressure sticking, the surface of drill collars can be spiral-grooved.

Stress Relief Groove & Bore Back Box 

Stress relief grooves improve bending strength of pin and box connections and, therefore, durability. Stress relief grooves for box and pin are defined by API. Bore back box is a gradual reduction of internal diameter by gradually increasing material cross  sectional area at critical section. This will ultimately drastically reduce stress concentration during static / dynamic loading and prevents box connections from failure.  

Hardbanding 

We provide several hardbanding materials for customer’s choice: Arnco-100XT, Arnco-300XT,  TCS-8000.

Slip and Elevator Recess 

Slip and elevator recesses improve downhole handling efficiency and safety. Slip and elevator  recesses are machined in accordance with API 7-1.

Recommended Hardbanding Location

 -Drill collars with slip and elevator recesses (ZIP)

4” long wear pad above elevator recess,

1” long wear pad above slip recess,

10” long wear pad under slip recess.

-Drill collars with slip recess: 

10” long wear pad under slip recess, 

4” long wear pad above slip recess. 

-Drill collars without slip and elevator recesses: 

10” long wear pad at 30” from pin shoulder.