Materials of the Non--magnetic drill collars are from chrome manganese, low carbon austenific alloy obtained by combining a proprietary chemical analysis and a rotary hammer forging process. The material is resistant to stress corrosion cracking, with high mechanical properties, low magnetic permeability, excellent machineability and no tendency to galling.

Magnetic permeability (when MPS=l x l0５/4?Nm)
* Relative Max: 1.010.
* Average: Uµr 1.005.
Magnetic Field Gradient (hot spots)
* Max: B 0.05 micro Tesla/100mm.
Mechanical Properties
The non--magnetic drill collars exhibit the mechanical properties indicated below along their entire length. This table is derived from test samples of steel taken from a point 1" below the surface.

Mechanical Properties

The non--magnetic drill collars are of a Cr--Mn type. The chemical composition is strictly controlled in order to ensure high strength and low permeability.
On inquiries and orders please specify:
* Outside diameter.
* Length.
* Connection Style.
* Stress relief grooves.
* Elevator and slip recess.
* Special features (magnets, scribe--line, top landing device, spiral grooves.)

Note: Other non--magnetic products also include:
Short collars, integral HWDP, subs, stabilizers, etc.