The article considers questions of demagnetization process at magnetic particle examination. It is reasonable to carry out demagnetization of the tested objects before and after the examination; the justification of this assertion is given in the paper. Various variants of demagnetization methods are analyzed; special attention is paid to peculiarities for demagnetization of large thick-walled objects and the problems to be solved in this direction. The author gives recommendations how to ensure stable demagnetized state of large objects against mechanical stress; the recommendations are based on experimental studies of specimens made of shipbuilding steels, and models of marine technical objects.
magnetic particle examination, demagnetization, welded joints, pipes
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