T9074-AS-GIB-010/271 Rev 1
4.3.1.2 Procedure. All magnetic particle procedures shall include as a minimum the following information: a. Material, shapes, and sizes to be tested. b. Type and direction of magnetization to be used. c. Equipment to be used for magnetization. d. Surface preparation (finishing and cleaning). e. Whether wet or dry method is to be used. f. Type of magnetic particles to be used. g. Whether continuous or residual method is used. h. Magnetizing current (amperage, alternating current [AC], or direct current [DC]), and type (full-wave, half-wave, etc.). i. Demagnetization. j. Test for concentration of particle suspension (if any). k. Sketches or a chart showing the typical inspection grid to be used. l. Method of particle application and removal. m. Applicable acceptance standards. n. Method for determining maximum coating thickness (if any). For the inspection of welds, the magnetic particle inspection procedure shall have the proven ability to detect a 1 ⁄ 16 -inch long by 0.006 inch wide by 0.020 inch deep notch (maximum dimensions) oriented 90 degrees to the magnetic flux. The notch shall be cut in a 3 ⁄ 8 -inch low alloy steel plate, and shall be filled flush with a nonconducting material, such as epoxy, to prevent mechanical holding of the indication medium. 4.3.1.3 Inspection Through Coatings. Magnetic particle inspection shall not be performed with coatings in place that could prevent the detection of surface defects in the underlying material. In addition, the procedure must be qualified with a coating of the same type and maximum possible thickness that will be encountered in the actual inspection. Furthermore, the procedure must also contain specific instructions as to what method the inspector is to employ to determine the maximum coating thickness in the area to be inspected. For non-ferromagnetic coating thicknesses of 0.003 inches and less, the qualification sample need not be coated. 4.3.1.4 Surface Preparation. Prior to inspection, surfaces shall be dry and free from any contamination that might interfere with the proper formation or interpretation of the magnetic particle patterns. With the exception of undercuts that are within specification allowances, the contour of welds shall blend smoothly and gradually into the base metal. Surface irregularities shall be removed to the extent that they will not interfere with interpretation of the test results. The final magnetic particle inspection shall be performed in the final surface and heat-treated conditions as specified in 1.4. 4.3.1.4.1 Cleaning and Masking. Grease or other matter that might interfere with the proper distribution and concentration or with the intensity, character, or definition of magnetic particle indications shall be removed from the surface undergoing the tests. All openings shall be plugged to prevent accumulation of magnetic particles or other matter where it cannot be completely or readily removed by washing and air blasting.
4.3.1.4.2 Cleaning Solution. Chlorinated solvents shall not be used on parts containing crevices.
4.3.1.5 Direction of Magnetization. To ensure detection of discontinuities having axes in any direction, not less than two separate inspections shall be carried out on each area. The second inspection shall be with the magnetic field at right angles to that used in the first inspection or as allowed by 4.3.3.4.1. A different means of magnetizing may be employed for the second inspection of the area.
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