Non- magnetic drill collars

According to API Spec.7 and SY/T5144, the non-magnetic drill collars are made of low carbon stainless steel, which are researched and developed independently by our technical personnel, With excellent lower Magnetic permeability, high strength of mechanical properties and outstanding resistant to stress corrosion cracking and no tendency to galling.

All threads are cold rolled, and machined with CNC Lathes –Double –shouldered, including some special threads.


Magnetic propety ( magnetic field = 1 x 05/4πA/m)

1. Average : Ur < 1.010

2. Magnetic field gradient : ΔB≤0.05μT

Anti-Galling treatment:

Drill collar threads are phosphatized or copperized in order to lower the possibility of connection galling.



Cold rolling thread roots :

Drill collar thread roots and stress relief features are cold rolled, which is helpful to reduce the fatigue failure of threads by minimizing crack initiation.