API SPEC 7-1 Spiral Drill Collar

API SPEC 7-1 Spiral Drill Collar

Spiral Grooving
Spiral Grooving In order to avoid differential pressure sticking in the hole.

1. Loss of weight is approximatively 4%, compared to slick drill collars.
2. Length of spiraled section allows reconditionning of connections.

Stress Relief Groove & Bore Back Box

Stress relief grooves improve bending strength of pin and box connections and durability. Stress relief grooves for box and pin are defined by API. 
Bore back box is nothing but gradual reduction of internal diameter by gradually increasing material cross sectional area at critical section. This will ultimately reduce drastically stress concentration during Static / Dynamic loading and prevents box connections from failure.

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.

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.

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