Non-magnetic drill collar

The non-magnetic drill collar is made of low chromium manganese alloy steel, which is forged through strict chemical composition analysis. All  non-magnetic drill collars produced from Sanjack have been tested for mechanical properties to ensure that their hardness, toughness, impact value and corrosion resistance meet the standards, with good low magnetic permeability and good machining performance.

The non-magnetic drill collar manufactured from Sanjack is made of stainless alloy steel with low magnetic permeability, and the cross-section of the pipe body is round.

The structure of non-magnetic drill collars is the same as that of ordinary drill collars, but their chemical composition and mechanical properties are different from those of ordinary drill collars. Nonmagnetic drill collar is a kind of drilling tool with special functions in directional well engineering. When the magnetic inclinometer is used to measure the inclination and azimuth of the borehole in directional wells, in order to protect the compass from the magnetic field of the drill string, a certain length of non-magnetic drill collar must be equipped in the drill string, so that the magnetic inclinometer can be located at a suitable position in the non-magnetic drill collar to measure the inclination, otherwise the correct measurement results cannot be obtained.


Permeability (magnetic field strength = 1 × 105/4πNm) :

Maximum value: 1.010, average value: μ r≤1.005

Magnetic field gradient: (hot spot) maximum value: B ≤ 0.05

OD range Yield strength Tensile strength Elongation Hardness Charpy impact energy
mm in MPa MPa % HB J
79.4~171.4 3 1/8~6 3/4 ≥758 ≥827 ≥18 NA NA
177.8~279.4 7~11 ≥689 ≥758 ≥20 NA NA

1) pin stress relief groove and box boreback

An pin stress relief can be used on all drill collars and downhole tools. It is a recommended option in situations where fatigue can occur as a result of bending. By removing unengaged threads in the high stress areas of the drill collar connection, it is less likely to crack due to fatigue because the bending will take place in the area of the connection with smooth surfaces that are free of stress concentrations.

2) Internal bore treatment

This option generates a compression level of at least 60,000 PSI at a given depth. This provides the collar with an excellent resistance to stress corrosion cracking.

3) Flexing

An optional outside profile can be machined to reduce the collar rigidity if required.

4) Elevator and slip recesses

Optional slip and elevator recesses are available to improve handling and safety. These two features can be used together or separately.

Feature Products

  • What Our Client Say About Sanjack Petro?

  • Be An Expert When Importing OCTG Tubing & Casing

    Check All Guides

    OCTG Tubing & Casing
    • Specifications and Grade of steel
    • PSL1 or PSL2
    • Corrosion and wear conditions
    Steel tubing pipe
    Steel Tubing Pipe Guide
    • Specifications and Grade of steel.
    • Connection type
    • Working temperature
    Polycore Tubing tubing Guide
    • Corrosive composition.
    • Abrasion condition
    • Working temperature.
    Anti-Corrosion OCTG Tubing Guide
    • Corrosive composition
    • Amount
    • Well conditions details.