Schoeller-Bleckmann is committed to on time delivery of high quality products continually seeking both cost reductions and technological improvements

The company's core values are efficiency, commitment to quality and flexibility to meet customer demands.

Schoeller Bleckmann Non-Magnetic Drill Collars are manufactured with higher contents of Chromium, Molybdenum, Nitrogen and other alloy elements to increase pitting corrosion resistance and stress corrosion resistance.


Pitting Corrosion Test Procedure

The test specimen is tested in a test cell at a controlled temperature (20°C/68°F) and in a test solution of chlorides (e.g. 1000 ppm CI). The test temperature and the chloride content of the test solution are principally variable.

The measurement of the Pitting Corrosion Potential of the specimen is carried out against a reference electrode (Kalomel-Electrode_. The steady increase in the applied potential is regulated by a motor potentiometer. The amount of increase of the potential is given with 150 mV/hr (comparable ASTM G5/87: 720mV/hr).

The Potential at which first a deviation from a constant current level can be examined is stated as the "Pitting Corrosion Potential".


Stress Corrosion Resistance

All Schoeller-Bleckmann Non-magnetic materials basically show a very good resistance against stress corrosion. For the application of these materials in high chloride muds a surface treatment as an additional protection against stress corrosion is strongly recommended.

Schoeller Bleckmann provides following special processes to apply a uniform compressive surface layer:

  • Hammer Peening
  • Roller Burnishing
  • Shot Peening


Tests carried out on each bar during production of drill collars & MWD-Parts

  • Tensile Test
  • Impact Test
  • Hardness Test
  • Metallographic Test (grain size)
  • Oxalic Acid Test (acc. To ASTM A262 – Pract.E)
  • Ultrasonic Test over whole length of the bar
  • Probe Test over whole length of the bar


Tests carried out on each melt

  • Chemical Analysis Relative Magnetic Permeability


Standard Certification Package

  • Certification Sheet
    Ultrasonic Report
    Probe Testing Report

Additional reports based on product (mainly for MWD / LWD – Parts)

  • Dimensional Report
    Surface Treatment Report
    Welding Report


Magnetic Properties

  • Relative Permeability : ≤1.001


Corrosion Resistance

    • Transgranular SCC
      Prevented by special surface treatments ("PLUS" treatment, roller burnishing, shot peening)
    • Intergranular SCC
      Quenching after warm forging prevents the occurrence of material sensitization. Each collar is tested according to ASTM A 262, Pract.A and E latest edition.


Non-Destructive Testing

  • Magnetic Inspection
    Drill collars are 100% tested by a proprietary probe-testing process ("Hot Spot" – test).Magnetic permeability of each collar is certified with the printout of probe testing.
  • Ultrasonic Inspection
    Each collar is ultrasonically inspected accordingly to ASTM E 114, latest edition as a minimum level.