drill collar(slick,spiral,non-magnetic)

Drill collar:
Our drill collars are manufactured from 4145H modified steel.Drill collars are bored and drifted to API Spec7-1 and fully heated to meet or exceed the mechanical property requirements of API Spec7.Hardness range of 285-341HB and a charpy V notch impact value of 54joules are guaranteed one inch below the surface.
On enquiries and orders ,please specify:
Slick or spiral;
Drill collar OD;
Drill collar bore:
Length of drill collar;
Connection type;

Stress-relief grooves:
Stress-relief grooves decease the frequence of fatigue failures by improving the bending strength of pin and box connections and reducing high stress concentrations.Sress-relief features are manufactured in compliance with API Spec7,unless otherwise specified by customers.

Slip recess and elevator recess :
Shenlong offers optional elevator and slip recesses to improve handling efficiency and safety.The
upper radius of elevator recess is cold-rolled to increase product life.Slip and elevator recesses can be used together or seperately.Unless otherwise specified,slip and elevator recesses are machined in compliance with API RP7G guidline.