MT

PROCEDURE

FOR

MAGNETIC PARTICLE EXAMINATION

(PROCEDURE NO: - DP- 25 Rev.00 Date: - 04/04/2015)

Sr.No. Date Details Revision Prepared By

Signature

Approved By Reviewed By

LEVEL-III

01 04/04/2015First Issue for Approved

and Reviewed 00

Procedure No. DP-25 Rev.00 of 11

CONTENTS

Sr.No. Contents Page No.01 Scope 0302 Reference Documents 0303 Personnel Qualification 0304 Technique 0305 Surface conditioning 0306 Equipment 0407 Examination Medium 0408 Nonmagnetic Surface Contrast Enhancement. 0509 Calibration of Equipment 0510 Magnetizing field adequacy 0511 Examination 0612 Interpretation and Acceptance Standard 0713 Marking 0814 Repair Requirement 0815 Demagnetizing 0816 Post Examination Cleaning 0817 Records 09


1. Scope

This procedure shall be employed for the magnetic particle examination of the casting, forging, Machined component, Welding Joints, HAZ Area and Parent Metal of thickness 3 mm to 50 mm (ferromagnetic material & its alloy) with visible and dry or wet (Visible and fluorescent) method. The procedure describes to the ability to detect imperfections which depends on the angle of its major axis with respect to the direction of the magnetic field. To ensure detection of imperfections in all orientations, the area of interest shall be magnetized in two directions approximately perpendicular to each other.

2. Reference Document

a) ASME Section V Article 7 “Magnetic particle examination”b) ASTM E-709 “Standard Guide for magnetic Particle Examination”c) ASNT SNT TC 1A “Personnel Qualification and Certification in Nondestructive Testing;”d) API 6Ae) API 16Cf) API 6Dg) ASME Sec-VIII Div 1h) ASME B16.34

3. Personnel Qualification

The personnel employed for the examination shall be certified to NDT Level-II (Magnetic Particle Testing) in accordance with ASNT SNT TC 1A.Only personnel level II or level III shall perform interpretation of the results.

4. Technique

Testing Area shall be examined by magnetizing it in two Directions 0 & 90 Degrees. The direction of magnetization shall be at approximately 90 Degrees to the first axis. Two legs of yoke shall be adjusted to provide the maximum coverage of the surface area but the maximum spacing between two legs shall not exceed 150 mm. Effectiveness of the procedure shall be verified by placing Pie Gauge field indicator in theEquidistant from the yoke poles. With the exception of the pie gauge Discontinuity parallel to the field, all other discontinuities should be clearly seen.For this technique Alternating current or Direct current shall be used for magnetize the Testing area.

5. Surface Conditioning


5.1 Satisfactory results are usually obtained when the surfaces are in as-weld conditions. However, surface preparation by grinding or machining may be necessary where surface irregularities could mask indications due to discontinuities.5.2 Prior to magnetic particle examination, the surface to be examined and all adjacent areas within at least 1” shall be dry and free of all dirt, grease, lint, scale, welding flux and spatter, oil or other extraneous matter that could interfere with the examination.5.3 Cleaning may be accomplished using detergents, organic solvents, de-scaling solutions, paint removers, vapour degreasing, sand or grit blasting, or ultrasonic cleaning methods.

6. Equipment

“Magnaflux” makes or Similar Electromagnetic Yoke shall be used having Following characteristics:-A) Lifting Capacity: - In DC current, 135 N (30 lb) with 2 to 4 inch pole spacing and 225 N (50 lb) with 4 to 6 inch pole spacing/ In AC Current, 45 N (10 lb) with 2 to 4 inch. pole spacing.B) Type of current: - AC / HWDCC) Type of Yoke: - Articulated “C” type adjustable- Pole spacing.D) BlowerE) UV Light

7. Examination medium

The finely divided ferromagnetic particles used for the examination shall meet the following requirements.(a) Particle Types. The particles shall be treated to impart color (nonfluorescent pigments) in order to make them highly visible (contrasting) against the background of the surface being examined.(b) Particles. Dry and wet particles and suspension vehicles should be in accordance with SE-709.(c) Temperature Limitations. Particles shall be used within the temperature range limitations set by the manufacturer of the particles or if not specify maximum temperature shall be 55°C.(d) As an Examination Medium Magnaflux Make 7HF (for visible method) and Zyglo (for fluorescent method) Prepare bath can be used.

Wet particles

Wet Particle (powder mixed in suspension Liquid) shall be check bath concentration determined by measuring its settling volume. This is accomplished through the use of


an ASTM Test Method D 96 pear-shaped centrifuge tube with a 1.5-mL stem (0.1-mL divisions) for nonfluorescent suspensions. Before sampling, the suspension should be run through the recirculating system for at least 30 min to ensure thorough mixing of all particles which could have settled on the sump screen and along the sides or bottom of the tank.Wet Particle shall be apply by spraying on examination surface.Concentration. Take a 100-mL portion of the suspension from the hose or nozzle, demagnetize and allow it to settle for approximately 60 min with petroleum distillate suspensions or 30 min with water-based suspensions before reading. The volume settling out at the bottom of the tube is indicative of the particle concentration in the bath.Settling Volumes. For fluorescent particles, the required settling volume is from 0.1 to 0.4 mL per 100 mL of vehicle for nonfluorescent particles 1.2 to 2.4 mL per 100 mL unless otherwise specified by the particle manufacturer. Concentration checks shall be made at least every stated shift and eight hours.

Dry Particles

Dry particle shall be treated to impart color in order to make them highly visible against the background of the surface being examined. Dry particle shall be applied by spraying with the use of blower on examination surface.

8. Nonmagnetic Surface Contrast Enhancement.

Nonmagnetic surface contrasts may be applied by the examiner to uncoated surfaces, only in amounts sufficient to enhance particle contrast. When nonmagnetic surface contrast enhancement is used, it shall be demonstrated that indications can be detected through the enhancement. Thickness measurement of this nonmagnetic surface contrast enhancement is not required.

9. Calibration of equipment

The magnetizing force of yokes shall be calibrated by determining their lifting power.9.1 Prior to use, the magnetizing power of electromagnetic yokes shall have been checked within the past year. The magnetizing power of permanent magnetic yokes shall be checked daily prior to use. The magnetizing power of all yokes shall be checked whenever the yoke has been damaged or repaired.9.2 Each alternating current electromagnetic yoke shall have a lifting power of at least 10 lb (45 N) at 2 to 4 inch. Pole spacing that will be used.


9.3 Each direct current or permanent magnetic yoke shall have a lifting power of at least 30 lb (135 N) at 2 to 4 inch. Pole spacing and 50 lb (225 N) at 4 to 6 inch. That will be used.9.4 Each weight shall be weighed with a scale from a reputable manufacturer and stenciled with the applicable nominal weight prior to first use. A weight need only be verified again if damaged in a manner that could have caused potential loss of material.9.5 Light Meters. Light meters shall be calibrated at least once a year or whenever a meter has been repaired. If meters have not been in use for one year or more, calibration shall be done before being used.

10. Magnetizing field adequacy

When it is necessary to verify the adequacy or direction of the magnetizing field, a Pie-shaped field indicator shall be used by positioning the indicator on the surface to be examined.When using this indicator, a suitable flux or field strength is indicated when a clearly defined line of magnetic particles forms across the copper face of the indicator when the magnetic particles are applied simultaneously with the magnetizing force.When a clearly defined line of particles is not formed, or is not formed in the desired direction, the magnetizing technique shall be changed or adjusted.

11. Examination

11.1 Preliminary ExaminationBefore the magnetic particle examination is conducted, a check of the examination surface shall be conducted to locate any discontinuity surface openings which may not attract and hold magnetic particles because of their width.

11.2 Direction of magnetizationAt 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.

11.3 Method of examinationExamination shall be done by the continuous method that is: the magnetizing current remains on while the examination medium is being applied and while excess of the examination medium is being removedWet medium shall be applied to the surface by spraying, flowing, blowing or pouring to provide abundant source of Magnetic particles.


Dry Particles. The magnetizing current shall remain on while the examination medium is being applied by blower and while any excess of the examination medium is removed.Wet Particles. The magnetizing current shall be turned on after the particles have been applied. Flow ofparticles shall stop with the application of current. Wet particles applied from aerosol spray cans may be applied before and/or after magnetizing current is applied. Wet particles may be applied during the application of magnetizing current if they are not applied directly to the examination area and are allowed to flow over the examination area or are applied directly to the examination area with low velocities insufficient to remove accumulated particles.

11.4 Examination coverageAll examination shall be conducted with sufficient overlap to assure 100% coverage at the required sensitivity (as far as possible).

11.5 Excess Particle RemovalAccumulations of excess dry particles in examinations shall be removed with a light air stream from a bulb or syringe or other source of low pressure dry air. The examination current or power shall be maintained while removing the excess particles.

12. Interpretation and Acceptance Standard

InterpretationThe interpretation shall identify if an indication as false, nonrelevant, or relevant. False and nonrelevant indications shall be proven as false or nonrelevant. Interpretation shall be carried out to identify the locations of indications and the character of the indication. Broad areas of particle accumulation, which might mask indications from discontinuities, are prohibited, and such areas shall be cleaned and reexamined.Evaluation should be done at adequate ambient lighting (Minimum 1000 Lux) for non fluorescent, which Measure with calibrated Lux meter.Black (Ultraviolet) Light:Black Light Intensity — The black light intensity at the examination surface is recommended tonot be less than 1000 _W/cm2 when measured with a suitable black light meter.7.1.2.2 Black Light Warm-up — When using a mercury vapor bulb, allow the black light to warm up fora minimum of five minutes prior to its use or measurement of the intensity of the ultraviolet light emitted.7.1.3 Dark Area Eye Adaptation — The generally accepted practice is that an inspector be in the darkened


area at least one (1) minute so that his/her eyes will adapt to dark viewing prior to examining parts under UV illumination.(Warning — Photochromic or permanently tinted lenses should not be worn during examination.)

All indications are not necessarily imperfections however, since excessive surface roughness, magnetic permeability variations etc. may produce similar indications.An indication of an imperfection may be larger than the imperfection that causes it; however, the size of the indication is the basis for acceptance evaluation. Only indications, which have any dimension greater than 1.5 mm shall be considered relevant.a) A linear indication is one having a length greater than three times the width.b) A rounded indication is one of circular or elliptical shape with a length equal to or less than three times its width.c) Any questionable or doubtful indications shall be re-examined to determine whether or not they are relevant.

Acceptance standards

If more stringer then below acceptance criteria not provided then it shall be apply as below. Indication with major dimension greater than 1/16 inch (1.6 mm) shall be considered relevant.

For Bodies, Bonnets, Choke, Kill lines, and End and outlet connections

As per API 6A & 16C:

If more stringer then below acceptance criteria not provided then it shall be apply as below. Indication with major dimension greater than 1/16 (1.5 mm) inch shall be considered relevant.

12.1 No relevant rounded indication with a major dimension equal to or greater than 4.8 mm (3/16 in.)12.2 No more than ten relevant indications in any continuous 40 cm2 (6 in2) area12.3 Four or more relevant indications in a line separated by less than 1/16 inch (edge to edge) are

unacceptable. 12.4 No relevant indications in the pressure contact sealing surfaces.

For weld

12.5 All applicable 12.1 to 12.4 12.6 No relevant liner indication 12.7 No rounded indication greater than 3 mm (1/8 inch) for weld whose depth is 15.9 mm (5/8 inch) or

less; or 4.8 mm (3/16) inch for welds whose depth is greater than 15.9 mm (5/8 inch).


As per API 6D:

MT on casting as per ASME Sec-VIII div 1 Appendix 7Surface indications determined by magnetic particle examination shall be compared with those indicated in ASTM E125, Reference Photographs for Magnetic Particle Indications on Ferrous Castings, and shall be removed if they exceed the following limits:Type DegreeI. Linear discontinuities (hot tears and cracks) AllII. Shrinkage 2III. Inclusions 3IV. Chills and chaplets 1V. Porosity 1

MT on casting as per ASME B16.34Maximum acceptable indications are as follows;a) Linear Indications.1) 8mm (0.3 in.) long for materials up to 13 mm (0.5 in.) thick2) 13mm (0.5 in.) long for materials 13mm to 25mm (0.5 in. to 1.0 in.) thick3) 18mm (0.7 in.) long for materials over 25mm (1.0 in.) thick

For Linear indications, the indications must be separated by a distance greater than the length of an acceptable indication. A linear indication is one with length in excess of 3 times the width.

B) Rounded indications1) 8mm (0.3 in.) diameter for materials up to 13mm (0.5 in) thick2) 13mm (0.5 in.) diameter for materials over 13 mm (0.5 in) thick. Four or more rounded indications in a line separated by 1.5mm (0.06 in.) or less edge-to-edge are unacceptable. Rounded indications are those that are not defined as linear indications.

C) Any round or liner indication shall not exceed 5 mm

MT on Forging, Bolting surface area and machined surfaceAll surfaces to be examined shall be free of:

1) Relevant linear indications 2) Relevant rounded indications greater than 3/16 in. (5.0 mm) 3) Four or more relevant rounded indications in a line separated by 1/16 in. (1.5mm) or less (edge to edge).

13. Marking

Spot/s or areas showing relevant defect indication/s shall be marked so that they can beIdentified properly and can be repaired.


14. Repair Requirement

14.1 Any indication which is believed to be non-relevant shall be regarded as an imperfection unless it is shown by reexamination by the same method or by the use of other nondestructive testing method and/or by surface conditioning that, no unacceptable imperfection is present.14.2 After a defect is thought to have been removed and prior to making weld repairs, the area shall be examined by suitable methods to ensure it has been removed or reduced to an acceptable size.14.3 After repairs have been made, the repaired area shall be blended into the surrounding surface so as to avoid sharp notches, crevices, or corners and reexamined by the Magnetic Particle method and by all other methods of examination that were originally required for the affected area, except that, when the depth of repair is less than the radiographic sensitivity required, re-radiography may be omitted.14.4 All repaired areas shall be re-tested employing the same technique and steps.

15. De magnetizing

When residual magnetism in the part could interfere with subsequent processing or usage, the part shall bedemagnetized any time after completion of the examination. Alternating current yokes may be used for local demagnetization by placing the poles on the surface, moving them around the area, and slowly withdrawing the yoke while it is still energized.

16. Post cleaning.

When post-examination cleaning is required, it should be conducted as soon as practical using a process that does not adversely affect the part.The use of compressed air to blow off unwanted dry magnetic particles, drying of wet particles and subsequent removal by brushing or with compressed air and removal of wet particles by flushing with solvent.

17. RecordsThe indication detected will be recorded describing their shape, size and Location with sufficient detail so that same can be located in future from Recorded information. As a minimum, the type of indications (linear or rounded), location and extent (length or diameter or aligned) shall be recorded.The examination Report shall include the followingName of ManufacturerName of Purchaser,Material and thicknessProject No. , Job No.Date and Place of Inspection


Procedure identification and revisionMagnetic particle (visible or fluorescent, wet or dry)The position of Inspection Stage in Manufacturing ProcessThe Surface FinishThe Equipment Used and type of currentLighting EquipmentThe Magnetization UsedMap and record of indication of rejectable and nonrejectable indication.The Interpretation of Observations with Sketch.Examination personnel Identity


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