Methods for testing non- or weakly ferromagnetic test objects
AssigneeBasell Polyolefine GmbH
InventorAntonio Ling
Life of this patent
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Abstract
Methods of detecting carburization, nitriding or chromium depletion in a non- or weakly ferromagnetic test object using a permanent magnet having a magnet pull force equal to or greater than about 75N and measuring either the adhesive force to detach the magnet from the test object or the attractive force in which the magnet is being pulled towards the surface of the test object.
Claims16
A method of detecting carburization, nitriding or chromium depletion in a non- or weakly ferromagnetic coil, comprising the steps:
- a) applying a permanent magnet having a magnet pull force equal to or greater than about 75 N to a surface of the non- or weakly ferromagnetic coil;
- and
- b) measuring the adhesive force to detach the magnet from the coil.
A method of detecting carburization, nitriding or chromium depletion in a non- or weakly ferromagnetic coil, comprising the steps:
- a) positioning a permanent magnet having a magnet pull force equal to or greater than about 75 N at a fixed distance from a surface of a non- or weakly ferromagnetic coil, having a working surface defined as the surface of the magnet facing towards the surface of the coil and which working surface is not in direct or indirect contact with the surface of the coil;
- and
- b) measuring the attractive force in which the magnet is being pulled towards the surface of the coil.
A method of monitoring the conditions of coils for cracking hydrocarbons in a furnace, comprising the steps:
- a) applying a permanent magnet having a magnet pull force equal to or greater than about 75 N to a surface of the coils located in situ in a furnace;
- and
- b) repeatedly measuring the adhesive force to detach the magnet from the coils.
Dependencies are inferred from the claim text.