AS ISO 9934.3 pdf download

AS ISO 9934.3 pdf download.Non-destructive testing — Magnetic particle testing
1  Scope
This part of ISO 9934 describes three types of equipment for magnetic particle testing: — portable or transportable equipment; — fixed installations; — specialized testing systems for testing components on a continuous basis, comprising a series of processing stations placed in sequence to form a process line. Equipment for magnetizing, demagnetizing, illumination, measurement, and monitoring are also described. This part of ISO 9934 specifies the properties to be provided by the equipment supplier, minimum requirements for application and the method of measuring certain parameters. Where appropriate, measuring and calibration requirements and in-service checks are also specified.
4  Types of devices
4.1  Portable electromagnets (AC 1) ) 4.1.1  General Hand-held portable electromagnets (yokes) produce a magnetic field between the two poles. When testing according to ISO 9934-1, DC 1) electromagnets should only be used if agreed at enquiry and order stages. Magnetization shall be determined by measuring the tangential field strength, H t , at the centre of a line joining the centres of the pole faces of the electromagnet with pole extenders where used. The electromagnet with a pole spacing, s, is placed on a steel plate as shown in Figure 1. The plate shall have the dimensions (500 ± 25) mm × (250 ± 13) mm × (10 ± 0,5) mm and shall be of steel conforming to C22 (1.0402) of EN 10250-2. Periodic functional checks can be carried out either by the method described above or by a lift test. The electromagnet shall be capable of supporting a steel plate or rectangular bar conforming to C22 (1.0402) of EN 10250-2 and having a minimum mass of 4,5 kg, with the magnet poles set at their recommended spacing. The major dimension of the plate or bar shall be greater than the pole spacing, s, of the electromagnet. NOTE  To lift a steel plate with a mass of 4,5 kg requires a lifting force of 44 N.
4.2  Current generators
4.2.1  General Current generators are used to supply current for magnetizing equipment. A current generator is characterized by the open circuit voltage, U 0 , the short circuit current, I k and the rated current, I r (RMS-values). The rated current, I r , is defined as the maximum current for which the generator is rated at the duty cycle of 10 % and for a current “ON” time of 5 s if not otherwise specified. The open circuit voltage, U 0 , and the short circuit current, I k , are derived from the load-characteristic of the generator at maximum power (with any feedback controls disconnected). The load line of the generator can be derived by connecting two widely different loads, such as different lengths of cable, in turn to the generator. For the first cable, the current, I 1 , through the cable and voltage, U 1 , across the output terminals are measured and plotted, to give point P 1 on Figure 2. The process is repeated with a second load to give point P 2 . The load line is constructed by drawing a straight line between P 1 and P 2 . The open circuit voltage, U 0 , and short circuit current, I k , are then given by the intercepts on the axes, as shown in Figure 2.
4.3  Magnetic benches
4.3.1  General Fixed installation benches can include facilities for current flow and magnetic flow techniques. Magnetic flow can be achieved either by an electromagnetic yoke or a fixed coil. The characteristics of the current generator are defined in 4.2. When facilities for multidirectional magnetization are included, each circuit shall be independently controlled. Magnetization shall be sufficient to achieve the required detection capability in all directions. The characteristic of the electromagnetic yoke is the tangential field strength, H t , measured, in kiloamperes per metre, at the midpoint of the length of a cylindrical bar conforming to C22 (1.0402) of EN 10250-2, of specified dimensions (length and diameter) appropriate to the acceptance range of the equipment. If the bench is to be used for magnetic flow testing of components longer than 1 m, or segments of the length are magnetized individually, the supplier shall define how magnetizing capability is determined. This shall include a specification of the tangential field strength for a bar of suitable length and diameter.