Direct magnetization occurs when the electric current is passed through the test object and a magnetic field is formed in the material. Magnetic particle Inspection (MPI) is a non-destructive testing (NDT) process for detecting surface and shallow subsurface discontinuities in ferromagnetic materials such as iron, nickel, cobalt, and some of their alloys. In between the head and tail stock is typically an induction coil, which is used to change the orientation of the magnetic field by 90° from the head stock. A device is used to create a magnetic field on the weld surface. Magnetic Particle Inspection (MPI) Services. The normal reversing DC demag cycle on modern equipment should be 18 seconds or longer. The process involves inducing a magnetic field on a component, and dry or wet magnetic particles are applied. Chemical Testing Weld Qualification Testing Metallurgical Testing Hydrostatic Testing Pressure Equipment Inspections NDT Non-Destructive Testing ACFM - Alternating Current Field Measurement NDT - vacuum Box (Bubble) Test NDT - Penetrant Examination/Test (DPI,LPI,FDPI,PT) NDT - Magnetic Particle Test (MPI/FMPI/MT) Then current is passed through the part again. Magnetic Particle Inspection(MPI) 3. It is dangerous to use kerosene or mineral spirits as a carrier due to the risk of fire. Direct magnetization occurs when the electric current is passed through the test object and a magnetic field is formed in the material. Magnetic Particle Testing (MPI) Magnetic particle testing (MPI) detects surface and slightly subsurface discontinuities in ferromagnetic parts (susceptible to magnetization) such as carbon steel, iron, nickel, and some of their alloys. The process puts a magnetic field into the part. Dry powders are normally applied using hand-operated air powder applicators. 1. The part is either accepted or rejected, based on pre-defined criteria. The magnetic lines of force are perpendicular to the direction of the electric current, which may be either alternating current (AC) or some form of direct current (DC) (rectified AC). The presence of a surface or subsurface discontinuity in the material allows the magnetic flux to leak, since air cannot support as much magnetic field per unit volume as metals. An AC electromagnet is a better means to detect a surface indication than HWDC, DC, or permanent magnet, while some form of DC is better for subsurface defects. I-CAR, with the help of the American Welding Society (AWS), and many welding professionals, has developed a âhands-onâ performance test that measures the ability to â¦ Since 1944, we have grown to become one of the largest structural steel fabricators in the Midwest, with more than 40,000 tons of steel fabricated annually by our shops in Minnesota and Wisconsin. R Hamshaw, Introduction to the Non-Destructive Testing of Welded Joints, 2nd edition, Abington Publishing, Cambridge, UK, 1996 (ISBN 1 85573 314 5) C E Betz, Principles of Magnetic Particle Examination, published by the Magnaflux Corporation, 1967. Depending on requirements, the orientation of the magnetic field may need to be changed 90 degrees to inspect for indications that cannot be detected from steps 3 to 5. In Fig 1 a 36-inch coil can be seen then steps 4, 5, and 6 are repeated. DC is used for deeper penetration. AC decaying demagnetizing: this is built into most single phase MPI equipment. MT relies on a magnetic field and steel particles; a discontinuity in the weld allows the magnetic flux to leak, attracting the particles. When using a stationary horizontal system with DC, it can be hard to magnetize big sections for testing. Tensile load tests, bend tests, impact tests etc. `` coil shot '' flux leaks mix poured. 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