Magnetic particle inspection test procedure
In this post, I have outlined the detailed Magnetic Particle Inspection Test Procedure. You can use this procedure as it is or can modify it according to your need for inspection of welding or materials.
1.1 This procedure will be used for detecting cracks and other discontinuities at or near the surface in ferromagnetic materials. The technique used will be portable AC electromagnetic yoke (Longitudinal Magnetization)by using non-fluorescent ferromagnetic particles and acceptance standards, which shall be followed whenever Magnetic Particle examination is specified.
1.2 This procedure covers the Magnetic Particle Examination of Cyclically loaded & static loaded Fabricated components.
1.3 This procedure shall be used in the examination of the Structural Fabrication of XXXXX. 100% Magnetic Particle Inspection of, welds of XXXXX of all units & welds joining cross beam or XXXXX m shall be carried out.
1.4 The extent of examination shall be as per the Product Quality Plan.
2. Reference Documents
Applicable edition & addenda of the following:
- AWS 0 1.1 Edition 2006 or later, section 6
- ASME Section V Article 25 ASTM SE-709
- SNT-TC-1 A Edition 2021
- XYZ company Written Practice (Mention your company written practice number)
- XXX Client specification (Write client specification if any applicable)
3. Personal Qualification
3.1 Personnel performing Magnetic Particle Examination shall be qualified in conformance with the current edition of the American Society for Nondestructive Testing Recommended Practice No. SNT-TC-1A and XYZ Written Practice. Individuals who perform NOT shall be qualified for:
3.11. NDT Level II, or
3.12. NDT Level I working under the NDT Level II
3.2 Certification of Level I and Level II individuals shall be performed by a Level Ill individual who has been certified by:
(1) The American Society for Nondestructive Testing, or
(2) has the education, training, experience, and has successfully passed the written examination described in SNT-TC-1A.
3.3 Personnel involved in conducting the test, recording results, and evaluating the same against applicable acceptance standards shall be certified to at least Level II as per XYZ Written Practice.
3.4 In satisfying the requirements of 3.3, the qualification of the MT operator shall include a specific and practical examination which shall be based on the requirements of this code. This examination shall require the MT operator to demonstrate the ability to apply the rules of this code in the accurate detection and disposition of discontinuities.
4.1 Any portable AC Electromagnetic Yoke shall be used for magnetization. A triggering switch is built in the yoke handle, which permits the examiner to turn on the longitudinal magnetization after yoke legs have been properly positioned on the part being examined and turned off before the yoke is removed.
4.2 AC current shall be used for examination.
4.3 Prior to use, the magnetization power (lifting power) of the Electromagnetic Yoke shall have been checked within the past year. The magnetizing power of the yoke shall be checked whenever the yoke has been damaged or repaired.
4.4 The calibration of AC Electromagnetic Yoke shall be done by determining its lifting power on a steel plate weighing 4.5 kg minimum at the maximum pole.
5. Surface Preparation
5.1 Prior to magnetic particle examination the surface to be examined and all adjacent areas within at least 1″ shall be clean and free from oil. Grease, sand, loose rust, scale, lint paint, weld spatter, and contaminations could interfere with the mobility of magnetic particle/ mask indications and/ or create false indications. The test surface shall not be excessively rough. In case of any doubt, light grinding of the surface may be carried out to determine the actual indication.
5.2 When the coating is applied temporarily to uncoated surfaces only in amounts sufficient to enhance particle contrast, it shall be demonstrated that the indications can be detected through the enhancement coating. If the part has a residual magnetic field from the previous examination it should be demagnetized prior to inspection. When the AC yoke technique is used the demonstration shall be in accordance with ASME Section V.
5.3 The white contrast Paint shall be applied by spraying to ensure uniform coating on the examination surface.
6. Examination Medium
6.1 The materials used in the inspection medium shall be finely divided ferromagnetic particles having high permeability and low retentivity and be of suitable size and shape to produce a magnetic indication of the defects.
6.2 Wet Particles shall be used and shall be applied by spraying.
6.3 It shall be of a color that will provide adequate contrast with the background surface being tested.
6.4 Examination shall not be performed by wet particles if the temperature of the wet particle suspension and surface of the part exceeds 135 °F (57 °C) or within temperature range limitations set by the manufacturer.
6.5 Following Magnetic Particle Mediums and White Contrast Paint are approved for use:
|ABC Co.||147 A||Black MPI Ink||Aerosol Spray|
|ABC Co.||14 HF||White Contrast Paint||Aerosol Spray|
6.6 The concentration of particles in the wet bath shall be measured by using a centrifuge tube (Settling Test), 100 ml sample of wet bath suspension shall be poured into the Centrifuge tube after thorough stirring. Settling time of a minimum of 30 minutes shall be given before taking the reading of the concentration of the settled particles. The concentration of particles shall be between 1.2 to 2.4 ml per 100 mi. bath concentration. The concentration shall be checked before each use. The concentration check for ready-to-use wet particles in an aerosol can not be done.
7. Examination Procedure
7.1 Examination shall be performed on AC mode unless otherwise specified.
7.2 Longitudinally magnetize the area to be examined by using a calibrated magnetic yoke. Leg spacing of the yoke shall not exceed 8″. Spacing of less than 3″ shall not be used.
7.3 At least two separate examinations shall be performed on each area. During the second examination, the lines of magnetic flux shall be approximately perpendicular to those used during the first examination.
7.4 Examination shall be performed by continuous method, that is; current/ magnetizing field shall remain on while the magnetic media is being applied and while the excess medium is being removed. A wet medium shall be applied to the surface by spraying, to provide an abundant source of magnetic particles.
8. Interpretation and Evaluation
8.1 A minimum light intensity of 100 FC (1 000 Lux) is required to ensure adequate sensitivity during the examination and evaluation of indications of magnetic particle testing using a non-fluorescent particle examination medium. The light source, a technique used and light level verification is required to be demonstrated one time, documented, and maintained on file.
8.2 Unless otherwise agreed, it is normal practice to interpret and evaluate the discontinuity based on the size of the indication. Only indications with major dimensions greater than 0.5mm or 0.019 inches shall be considered relevant.
8.3 A linear indication is one having a length greater than three times the width.
8.4 A rounded indication is one of circular or elliptical shape with a length equal to or less than three times the width.
8.5 Any questionable or doubtful indications shall be re-examined to determine whether or not they are relevant.
9. Acceptance Standards
9.1 Acceptance shall be in accordance with AWS D1 .1:2000 or later Section 6 for cyclically loaded connections or DIN EN 1290 along with an evaluation to ISO 5817, class B.
9.2 Following acceptance standards as per DIN EN 1290 along with an evaluation to ISO 581 7, class B shall apply.
NOTE: An indication of imperfection may be larger than the imperfection that causes it, however, the size of the indication is the basis for acceptance evaluation.
10. Repair examination
10.1 All repaired areas shall be re-examined by the same procedure as used for the original detection of the discontinuity. It is to be ensured before re-examination that a repaired area shall be blended into the surrounding surface. Blended areas shall not have sharp notches, crevices, or corners.
10.2 All observations of indication shall be done when the magnetizing current is on. Any indication, which is believed to be non-relevant or false, shall be regarded as relevant until the indication is re-examined to verify whether or not actual discontinuity is present.
11.1 In general demagnetization is not be applicable for AC type of electromagnetic yoke. If residual magnetism is up to 3 gausses, as measured with a calibrated Residual Field Indicator; demagnetization is not required. If It is more than 3 Gauss, demagnetize by moving yoke (in ON condition) away from the area with AC till it reduces to an acceptable value. (i.e. Less than 3 gausses)
11.2 If the subsequent operation requires demagnetization then shall be carried out as per the Product Quality Plan.
12. Post Cleaning
12.1 On completion of testing and interpretation, the part shall be cleaned by flushing of part with a suitable solvent for removal of wet particles or removal by brushing after the wet particles have dried.
13.1 Care shall be taken to ensure that cables and connections etc. are not loose and to avoid shock hazards. Due care should be taken in handling carrier suspension to avoid the risk of fire.
14.1 Recording of Indications: Supplier shall provide the client with all NOT Reports & defect rates.
14.2 Non Rejectable Indications: Non Rejectable Indication shall be recorded in the report.
14.3 Rejectable Indications: Rejectable Indications shall be recorded as to the type of indication (linear or rounded), length, and location.
14.4 Magnetic Particle Examination Report shall be prepared by at least NOT level II but not limited to:
- Supplier Name, Address and Supplier Code
- Client Purchase/Shop Order Number and date
- Identification Number, Revision Level and Revision date
- SDR(s)/QCR(s) and the following
- Project Number (Contract Number) & Equipment Code
- Drawing Number
- Identification of Part Tested
- Material and thickness
- Magnetic Particle materials Used
- Metal Temperature
- Dwell Time & Developing Time
- Lighting equipments
- Interpretation & Evaluation
- Signature with Date of the Person Performing, Interpreting and Evaluating the Magnetic Particle Test results.
14.5 All reports/ records shall be maintained during production and during at least the following1 0 years for all components produced.