INDEX1 INTRODUCTION .................................................................................................................................2 1.1 Scope ....................................................................................................................................... 2 2 REFERENCES...................................................................................................................................... 2 2.1 Normative references ................................................................................................................ 23 PERSONNEL QUALIFICATION .............................................................................................................. 24 SAFETY CONDITIONS ......................................................................................................................... 25 SURFACE PREPARATION ..................................................................................................................... 36 MAGNETIZATION ............................................................................................................................... 3 6.1 General Conditions .................................................................................................................... 3 6.2 Magnetization Techniques ......................................................................................................... 4 6.3 Magnetization Check Out ........................................................................................................... 57 UV-A RADIATION SOURCES ................................................................................................................ 5 8MAGNETIC PARTICLES ....................................................................................................................... 5 9 CALIBRATION .................................................................................................................................... 6 10 VISUAL INSPECTION CONDITIONS ..................................................................................................... 6 10.1 Coloured Products ..................................................................................................................... 6 10.2 Fluorescent Products ................................................................................................................. 6 11 GLOBAL BEHAVIOUR CONTROL (PERFORMANCE) ................................................................................ 6 12 Definitions and Indications Classification .............................................................................................. 7 12.1 Definition of Indications............................................................................................................. 7 12.2 Severity Levels .......................................................................................................................... 8 12.3 Clasification of the Indications ................................................................................................... 9 13 RESULTS INTERPRETATION .............................................................................................................. 10 14 INDICATIONS RECORD ..................................................................................................................... 10 15 DEMAGNETIZATION ......................................................................................................................... 10 16 CLEANING........................................................................................................................................ 10 17 INSPECTION REPORT ....................................................................................................................... 12 17.1 Annex I:Inspection Report Template ........................................................................................ 13 17.2 Annex II (For Information only): Reference Pictures. Linear indications (SM) .............................. 15 17.3 Annex III (For Information only): Reference Pictures. Linear and aligned indications (LM and AM) 17RECORD OF CHANGES1INTRODUCTIONThis specification is applicable to any casting component requiring Magnetic Particles inspection for its acceptance.1.1SCOPEThis specification defines the procedure and severity levels for the inspection of cast iron and ferromagnetic cast steels components using magnetic particles technique (whatever it is the casting technique).This specification covers the inspection procedures and acceptance criteria to be fulfilled by any casting, forging, rolled and welded product supplier. Inspection areas are not covered by this specification. These can be found in the part specification.2REFERENCES2.1NORMATIVE REFERENCESThe following documents are invoked as part of this specification and must be fulfilled to the extent defined. Unless specifically over-ruled by the inclusion of a date, or an issue letter or code, the latest issue shall always apply.3PERSONNEL QUALIFICATIONNDT-Personnel of the supplier must be qualified to one of the following certification standards: ∙SNT-TC-1A∙EN 473Gamesa Quality Assurance shall have access at any time to the NDT-Personnel qualifications.Gamesa Corporación Tecnológica (GCT) requires level II NDT personnel.Gamesa Quality deptartment shall investigate the documentation for qualifications before the work is commenced.4SAFETY CONDITIONSTest by means of magnetic particles can require the use of toxic, inflammable and (or) volatile products. In this case, the zone of work must be ventilated and properly away from the source of heat and flames. It is convenient to avoid the prolonged or repeated contact of the skin and mucous with detection products and contrast paints.Test materials must be according to instructions of the manufacturer. At any moment, the national standard of security, accident prevention must be fulfilled in relation to electricity, dangerous substance manipulation and protection of people and the surrounding environment.In case of UV-A source use, it is necessary to make sure that the filtered radiations of the UV-A source do not impact directly at the eyes of the operator. The UV-A filters must be kept in good conditions, independently of being integral to the source or separated.5SURFACE PREPARATIONZones to be inspected by magnetic particles must be dry and free of dirty, oil, grease, oxide particles, slag products and any other product that could have an effect in the sensitivity of this test.Surface conditions described above can be reached by means of detergent, organic solvent, cleaner, sand blasting, vapor grease remover, etc.Quality surface requirements depend on the size and orientation of the discontinuities to be detected. The surface shall be prepared properly in order to be able to detect all the relevant indications considering the possibility to machine or grind the surface to separate false from relevant indications, due to the fact that irregularities could cover an indication of a possible defect.Non magnetic surface coatings up to 50μm (0,05 mm) thickness, such as continuous adherent paint systems (without cracking), usually do not modify detection sensitivity. Thicker coatings reduce it dramatically, so it is necessary to check out the level of sensitivity.There must be contrast enough between the indications and the surface to be inspected. When using white light (non fluorescent technique), it can be necessary the use of adherent, uniform paint (varnish) with approved contrast. If the magnetization electrode technique is used, all no conducting material must be removed from the contact areas.6MAGNETIZATION6.1GENERAL CONDITIONSMinimum induction in the component shall be at least 1T. Flux density is obtained by a relatively high permeability and a tangential magnetic field of 2kA/m.The test shall be performed using the continuous method, namely, the magnetic field shall be applied by the time the particles are drop on the component, and the excess removed.In case that flaws or any other discontinuity are susceptible to orient themselves in a particular direction, when possible, the magnetic flux shall be oriented in such a particular direction.It can be considered that the magnetic flux is effective, if allows to detect discontinuities with an orientation no higher than 60º with the optimum sensitivity direction. It can be then obtained a complete coverage performing the magnetization of the surface in two perpendicular different directions (maximum deviation ≤ 30º).Test shall be carried out overlapping consecutive positions in order to guarantee that 100% of the surface is covered.1 Directions of the magnetic field2 Optimum sensibility3 Sensibility decrease.4 Low sensibilityα Angle between the magnetic field and the indication direction.αmin. Angle for indications detection.αi Example of indication orientation.Figure 1. Directions of detectable indications.6.2MAGNETIZATION TECHNIQUESTo carry out the magnetization process an alternating current PORTABLE ELECTROMAGNETS (Yoke) will be used.Both poles of the alternating current electromagnet are placed in direct contact with the component to test, producing a magnetic field between both poles. The area of each component, near by each pole is not possible to test due to the high magnetic field intensity. It must be ensured a complete coverage of areas to be inspected.Equipment supplier must provide all necessary technical data (recommended distance between poles, poles cross section measurements, wave shape, current control method and wave shape, maximum current flow time, dimensions, weight, etc.)Electromagnets (yokes) must comply with the following requirements at room temperature 30ºC and working at maximum power.❑Cycle coefficient………≥ 10%❑Current flow time.......... ≥ 5s❑Handle surface temperature…. ≤40 ºC❑Tangencial field Ht at Smax...... ≥ 2 KA/m (RMS).❑Rise force……..≥ 44 N (*)(*) To lift up 4.5 kg it is required an elevation force of approximately 44N.Electromagnets must be equipped with a power switch on / off, if possible mounted on the handle.Other techniques can be applied (current flux between electrodes, fix equipment, coils, central conducting or adjacent, etc.) and current (continuous, rectified), if previously agreed with GCT.6.3MAGNETIZATION CHECK OUTThe easiest way for checking out magnetization is to control a test component with small discontinuities made artificially or naturally in the most critical zones. In the absence of these specimens, it can be used any other method based on the stated principles.7UV-A RADIATION SOURCESIt can be carried out the test with UV-A radiation (between 315nm and 400nm) using a source with a maximum nominal intensity of 365nm.Radiation shall be measured in working conditions, on the testing surface, using a UV-A radiometer.Measurement shall be carried out once the intensity of the lamp is constant (no less than 10 minutes after switch it on).The supplier of the source must provide all the necessary technical data (surface temperature in the UV-A radiation housing, after 1 hour time, cooling system, electrical requirements, dimensions, weight, irradiated area at 400mm from the source, irradiance after 15 minutes; 220 hours, luminance after 15 minutes; 220 hours, etc.)UV-A sources must satisfy minimum requirements listed below at a room temperature of 30ºC❑Filter resistant to splashes of the detection media.❑Protection against the dangers caused by portable units when in stand by position.❑UV-A Irradiance at 400mm from the source............... ≥ 10 W/ m❑Luminance at 400mm form the source............... ≤ 20 lx❑Surface handle temperature ............. ≤ 40º C8MAGNETIC PARTICLESMagnetic particles to be used shall be applied in wet conditions (in a suitable carrier solution, previously shaked to mix up and provide a homogeneous particle – liquid suspension).High permeability and low retentivity particles shall be used with suitable size and shape for the procedures and techniques used for the evaluation. Magnetic particles colour will contrast properly with the surface to be tested.GCT suggests using fluorescent magnetic particles in wet conditions. GCT must approve the use of any other kind of magnetic particles.Magnetic particles suspension can be obtained directly mixed to use or made up using concentrate products, including powders and solid solutions.Magnetic particles shall be applied so that they produce an uniform and light coverage on the surface to be tested, while the magnetization current is set up.After magnetic field application and before switching off the electrical current, remaining particles shall be removed without distortion of the particles that contribute to the indication on the discontinuity.9CALIBRATIONAll the equipment for work (yoke, etc.) and measurement (white light luxometer, UV-A radiometer, etc.) used for the test must be officially calibrated and the corresponding information to disposition of GCT if it is required.10VISUAL INSPECTION CONDITIONSBefore coming up with the procedure of inspection, a visual inspection shall be performed all over the surface to test. When it is difficult to do so, magnetic equipment or specimen can be moved in order to have a clear access to the whole component. Special attention must be paid in order to avoid the modification of the indications previously detected and registered.10.1COLOURED PRODUCTSWhen using coloured products:a)It is necessary a good contrast between the detection product and the tested surface;b)Surface to be tested must be lighted using natural or artificial white light (it is not allowed the use ofmonochromatic sources such as sodium lamps), avoiding shine or reflection and using a level of luminance higher than 500lx (lux).10.2FLUORESCENT PRODUCTSWhen using fluorescent products for detection purposes, examination zone must be dark up to 20lx as a maximum illumination level. Examination area must be illuminated using UV-A. UV-A energetic illumination must be at least 10 W/m2(1000 W/cm2) measured on the surface to be tested. A higher level of UV-A luminance allows the use of white light intensity proportionally higher, always considering that it is necessary to have a clear contrast between the indications and the surface subjected to evaluation.Enough time must spend before the test in order that eyes become accustomed to the reduction of ambient illumination.Ultraviolet lamp shall be switched on some time before (usually 5 minutes or what stated by the manufacturer) before using, in order to guarantee a suitable level of radiation.It is not allowed the use of photochromatic glasses when working with UV-A light, because when exposed to this radiation can become dark and this effect could reduce the capacity to detect discontinuities in people wearing these glasses.11GLOBAL BEHAVIOUR CONTROL (PERFORMANCE)Before beginning the test, it is recommended to do a global behavior control (performance) of the used method. That is useful to bring up anomalies in both operational method, magnetization technique, or in the detection instrument.The most reliable test to perform is that to be done on a representative sample having natural or artificial discontinuities with previous knowledge of location, type, dimensions and distributions. Control samples have to be demagnetizes and be exempt of indications previously done in other test.In absence of production samples with real known discontinuities, artificial samples can be made up with defects, for instance a cross magnetic flux indicator or a similar one as it is shown in Figure 2.Figure 2. Magnetic Particles field indicator according to ASME V, article 7, T-727.12 DEFINITIONS AND INDICATIONS CLASSIFICATIONSpecial attention must be paid in order to separate real indications from the false ones, for example those corresponding to scratches, section changes, limit between zones with different magnetic properties or magnetic written.It is necessary to take control and define the procedures to identify and remove, if possible, the source of these false indications.Discontinuities usually observed in cast components are defined in Table 1 and are reviewed with symbols (A, B, C, D, E, F, or H). These discontinuities can give to indications, magnetic diagrams or groups of indications all over the surface. These indications can all be of different types.inspection.12.1 DEFINITION OF INDICATIONSIndications corresponding to different discontinuities when testing using magnetic particles technique may have different shape and size. In order to distinguish between indications and discontinuities it is useful the use of a relationship between length, L, and width, W./ Pieces of low carbon steel welded/ Non metallic handle with adequate length/ Artificial defect between all pieces/ Copper piece12.1.1Non linear Indications (SM)Indications are considered to be non linear if length, L, is lower than three times width, W.12.1.2Linear Indications (LM)Indications are considered linear if length, L, is equal or higher than three times width, W.12.1.3Aligned Indications (AM)Indications are considered to be aligned in the following cases:a)Non linear Indications: Distance between indications is lower than 2 mm, and at least, threeindications are observed.b)Linear Indications: Distance between two indications is lower than length, L, of the biggerdiscontinuity aligned.Aligned indications are considered as a simple indication. Its length is equal to the total length, L, of the corresponding alignment (see Figure 3).Length L, is the distance between the starting point of the first indication and the ending point of the last discontinuity L l ₁ + l ₂ + l ₃ + l ₄ + l ₅Figure 3. Example of total length for aligned indications.12.2SEVERITY LEVELSSeverity levels are fixed as a reference scale and are defined as a function of the indications.12.2.1Non Linear IndicationsFor non linear indications, severity levels are defined (see Table 2) using the following criteria:a)Length (largest dimension), L1, of the smaller indication taken into account.b) When possible to perform, maximum total surface of the indications detected in a given area(rectangle of 105 mm x 148mm).c)Maximum Length, L2, of the observed indications.12.2.2Linear and aligned indicationsIn case of linear or aligned indications, severity levels (see Table 3) are defined as follow:a)Length (largest dimension), L1, of the larger indication that has been considered.b)Maximum length, L2, of the linear and aligned observed indication.c)The sum of lengths of each linear or aligned indication, within a 105mm x 148mm rectangle, thatexceeds the length L1.12.2.3Severity Level SelectionSeverity level can be chosen from Tables 2 and or 3 and, when necessary, from the reference pictures that appear in annex II and III. Reference pictures are taken 1:1 scale and are included herein as an example.Table 2 and Annex II are referred to non linear indications (isolated) (SM).Table 3 and Annex III are referred to linear indications (LM) and aligned (AM).The selection of the reference picture depends on the section thickness.12.2.4Cross section thickness rangeThree different thicknesses are established for the cross section (see Table 3):a)t ≤ 16mmb)16mm ≤ t ≤ 50mmc)t > 50mmBeing t the section thickness.12.3CLASIFICATION OF THE INDICATIONSTo classify a discontinuity indication, it is necessary to place a 105mm x 148mm rectangle profile is the most critical zone, that is in the zone where high severity level indications appear.12.3.1Non Linear IndicationsJust consider indications having lengths larger than L1 (see Table 2).The sum of the areas of each one of the indications must be calculated (if the surface of the casting is smaller than the reference surface, area of the indications must be proportionally reduced).Length of the indications must be measured.The level of the indications (SM) shall be carried out according Table 2.Note: Only values defined in this Table are valid and reference pictures are just included for information (see Annex II).Table 2. Severity Levels in magnetic particles inspection for isolated non linear indications.12.3.2Linear and aligned indicationsLength L of the isolated indications larger to the minimum length defined by the required severity level must be measured. The sum of the indications within a rectangle of 105mm x 148mm must be carried out.The thickness of the section, t, must be measured in the zone in which inspection is performed.The level of indications LM and AM must be determined with the help of Table 3.The sums of the lengths of the linear and aligned indications that are higher than the minimum length are to be measured, and the result must be compared with the specified "accumulated" length in Table 3.Some of the severity levels defined in Table 3 are illustrated in the same reference picture, shown in Table 4. In some cases, the equivalence with the picture is just approximate due to slightly differences in parameters showed in Table 3. In these cases, equivalences are indicated using 1) mark in Table 4.12.3.3Reference PicturesReference pictures that correspond to non linear indications, linear and aligned indications (see Table 2 and Table 3) are shown in Annex II and III, respectively.A real picture and a reference picture are considered to be equivalent when the same total surface has been detected for non linear indications and/or the same length for linear or aligned indications.13RESULTS INTERPRETATIONCast components tested according to this specification are considered SUITABLE (ACCEPTABLE) if discontinuities correspond to a level equal or lower than that stated as reference.14INDICATIONS RECORDAcceptable indications are not to be recorded unless otherwise specified directly by GCT.Indications must be recorded in such a way that they are completely defined in both characteristics (type, dimensions, etc.) and location.Record shall consist of sketches, drawings or photography. Other recording media could be used if previously agreed with GCT.15DEMAGNETIZATIONIn all cases in which the remaining magnetism could interfere with the following processes or applications this element must be demagnetized once the test has been finished, using suitable techniques to reach a minimum value of residual magnetism in the component.a)Demagnetization requires the use of an decreasing alternating magnetic field equal or higher thanthe one used for the magnetization.b)Components previously magnetize using continuous current require the use of low frequency currentor alternating change with continuous current.c)Demagnetization is necessary before carrying out the control when the level of residualmagnetization is so that any adherent fillings, opposite flow or false indications can limit the effectiveness of the control.16CLEANINGWhen necessary, after the control and acceptance, all the components must be cleaned to eliminate the detection product.Note: Only values defined in this Table are valid and reference pictures are just included for information (see Annex III).Table 3. Severity levels in magnetic particles inspection for linear (LM) andaligned indications (AM).1⁾Table 4. Linear indications (LM) and aligned (AM).17INSPECTION REPORTInspection report must include at least the following information:a)Name and address of the organism performing the inspection and the location where it was carriedout.b)Name and address of the manufacturer.c)Name and address of the customer.d)Data referent to the component inspected (reference, number, etc.)e)Examination procedure and section defining acceptance criteria.f)Surface conditions of the component.g)Instrumentation used for the test and reference.h)Electrical current characteristics.i)Type and color of the particles (brand and reference).j)Sketch with detected indications.k)Interpretation and evaluation of indications.l)Test Date.m)Name, qualification level and sign of personnel performing the inspection.Title: Magnetic Particles Inspection in Cast Iron 17.1ANNEX I:INSPECTION REPORT TEMPLATE17.2ANNEX II (FOR INFORMATION ONLY): REFERENCE PICTURES. LINEAR INDICATIONS (SM) All reference pictures in this section are just for information purposes and must be used in the appropriate scale 1:1.10 mmFigure B.1 – Severity level SM 1.10 mmFigure B.2 – Severity level SM 2.10 mm Figure B.3 – Severity level SM 3.10 mm Figure B.4 – Severity level SM 4.10 mmFigure B.5 – Severity level SM 5.17.3ANNEX III (FOR INFORMATION ONLY): REFERENCE PICTURES. LINEAR AND ALIGNEDINDICATIONS (LM AND AM)All reference pictures in this section are just for information purposes and must be used in the appropriate scale 1:1.10 mmFigure C.1 – Severity level LM 1a or AM 1a.10 mmFigure C.2 – Severity level LM 1b o AM 1b [LM 2a* - AM 2a*].* Comparable with other levels.10 mmFigure C.3 – Severity level LM 1c o AM 1c [LM 2b* - AM 2b* or LM 3a* – AM 3a*].10 mmFigure C.4 – Severity level LM 2c o AM 2c [LM 3b* - AM 3b* or LM 4a* – AM 4a*]. * Comparable with other levels.10 mmFigure C.5 – Severity level LM 3c o AM 3c [LM 4b* - AM 4b* or LM 5a – AM 5a*].10 mmFigure C.6 – Severity level LM 4c o AM 4c [LM 5b* - AM 5b*].* Comparable with other levels.10 mmFigure C.7 – Severity level LM 5c o AM 5c.。
