标准MT工艺.docVIP

MAGNETIC PARTICLE TESTING PROCEDURE EQUIPMENT A.C. Electromagnetic Yokes Yokes (220V/50Hz Alternating Current) used shall be the fixed or articulated leg type. Calibration Yokes shall develop a minimum lifting force 5kg at maximum leg spread. The lifting force shall be checked as per code requirement. Examination Medium Wet Magnetic Particle Materials 1) The magnetic particles used for obtaining patterns of discontinuities shall be non-toxic and shall provide adequate contrast with the surface being examined. 2) The magnetic particles used for obtaining patterns of discontinuities shall be capable of exhibiting good visual contrast against the white backing medium. 3) White background contrast paint shall be used with black magnetic ink particles and shall not corrode or otherwise adversely affect the integrity of the steel components being examined. PROCEDURE The A.C. Yoke and the permanent magnet method shall be used to induce the required magnetic fields. Temperature during test Wet method magnetic particle examination shall not be performed if the surface temperature of the part exceeds 57(C. Time of Test According to Client specification, If no special requirement, Inspection of completed welds is to be performed at once after welding. Surface Preparation 1) The surface finish of the welds or the weld grooves shall be such that proper interpretation can be accomplished. The surface to be examined may be examined in the as-welded or as-rolled condition. However, surface irregularities that could mask indications of unacceptable discontinuities shall be removed by grinding, or other Client approved methods. 2) Prior to the examination, the surface to be examined, including 25mm on each side of the weld or weld groove, shall be dry and free of any dirt, grease, lint, scale, welding flux and spatter, oil or other extraneous matter that could interfere with the examination. Application of Examination Medium 1) Adequate contrast with the background of the surface bei