METHOD OF MAGNETIC INSPECTION OF DEFECTS OF LONG-LENGTH FERROMAGNETIC ARTICLES Russian patent published in 1995 - IPC

FIELD: nondestructive testing. SUBSTANCE: this method of magnetic inspection of long-length ferromagnetic articles relates mainly to electrically welded pipes and lies in magnetization of article and in reading of gradient of magnetic leakage field on its surface with the aid of two ferroprobe converters which signals are subtracted and by which difference defects in article are detected. Section of article under one of converters is additionally magnetized to higher level at which value of difference signal reaches minimal magnitude. Additional magnetization of section of article makes it possible to produce difference signal inversely proportional to value of defect field which enables informativity of test to be enhanced thanks to detection of defect along entire length of article. EFFECT: enhanced informativity of inspection of longitudinal continuous weld thanks to determination of its length. 2 dwg, 1 tbl