MT Procedure for Above Ground Storage Tank Rev. 0

MAGNETIC PARTICLE EXAMINATION PROCEDURE FOR WELDS IN STORAGE TANKS

PROC. NO. : IMSN/MT/17

REV. NO. : 0

DATE : October 15, 2010

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1. SCOPE

1.1 This procedure covers the performance of Magnetic Particle Examination and evaluation against applicable acceptance standards for welds (including their heat-affected zone) in carbon steel storage tanks using combination of Yoke magnetization technique with non-fluorescent wet particles.

1.2 This procedure is not intended to replace visual examination but will act as supplementary NDE method for finding open to the surface discontinuities.

1.3 This procedure is applicable in the performance of magnetic particle examination by PT. Inti Mutu Sejahtera Nusantara (IMSN).

1.4 Weld configurations to be examined, including thickness dimensions and base material product form shall follow Customer’s Drawing Requirements or NDE Map.

2. CODES AND REFERENCES

2.1 API 650 – Welded Tanks for Oil Storage, 11th Edition June 2007 November 2009 Addenda.2.2 API 620 – Design and Construction of Large, Welded, Low-pressure Storage Tanks, 11th

Edition February 2008 August 2010 Addenda.2.3 API 653 – Tank Inspection, Repair, Alteration, and Reconstruction, 3rd Edition December 2001

November 2005 Addenda.2.4 ASME B & PV Code Section V Article 7 and Article 25, 2007 Edition 2009 Addenda.2.5 ASME B & PV Code Section VIII Div. 1, 2007 Edition 2009 Addenda.2.6 IMSN’s NDE Personnel Qualification and Certification Procedure Doc. No.: IMSN/WP/01

Revision 0.

3. PERSONNEL QUALIFICATION

All personnel carry out Magnetic Particle Examination under this procedure shall be qualified and certified in accordance with IMSN’s NDE Personnel Qualification and Certification Procedure Doc. No.: IMSN/WP/01 Revision 0 which complies with ASNT Doc. No. SNT-TC-1A 2006 Edition.

4. EQUIPMENT AND MATERIALS

4.1 Magnetizing EquipmentEquipment used under this procedure shall be Alternating Current (AC) Yokes or Direct Current (DC) Yokes or Permanent Yokes type. The equipment shall satisfactorily meet the requirement defined in Par. 6.2 of this procedure.

Table 1 – Magnetic Particle Examination Medium

Manufacturer White Contrasting PaintPrepared

Black Ink BathTemp. Range

MAGNAFLUX WCP-2 7HF 5˚C – 70˚C

ELY WCP-712 or WCP-722 SUPRAMOR 4 5˚C – 70˚C

CIRCLE SYSTEM MI-GLOW WCPCIRCLESAFE

820AX5˚C – 70˚C

4.1 Examination MediumTable 1 shall be used in the performance of Magnetic Particle Examination under this procedure. At all times, valid materials certificates shall be available to any concerning parties for verification between the batch number stated in the certificate against the one printed on the aerosol cans.

5. SURFACE PREPARATION

5.1 Examination shall be conducted on uncoated (free from non-magnetic coatings) surfaces.



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5.2 Surface preparation by grinding, machining or mechanical wire brushing may be necessary where surface irregularities could mask discontinuities indications by false indications.

5.3 Prior to magnetic particle examination, the surface to be examined and all adjacent areas within at least 1 inch (25 mm) shall be dry and free from dirt, grease, lint, scale, welding flux and spatter, oil, or any non-magnetic coating.

5.4 Cleaning shall be accomplished using detergents, organic solvents, de-scaling solutions, paint removers, sand blasting.

5.5 Temperature on the surface of the part to be examined shall be controlled within those specified in Table 1.

6. CALIBRATION

6.1 Calibration of Lifting Weight StandardEach lifting weight standard shall be weighed with a scale from a reputable manufacturer or independent laboratory and stenciled with the applicable nominal weight. A certificate of the lifting standard stating its nominal weight shall be maintained on file . A weight standard need only be calibrated again if damaged in a manner that could have caused potential loss of material.

6.2 Calibration of Electromagnetic Yokes

6.2.1 Each AC yoke shall be able to lift a standard weight of at least 10 lb (4.5 kg) at minimum 6 inch pole spacing for minimum of 3 seconds. This calibration shall be verified every year or whenever the electromagnetic yoke is suspected to have been damaged or after being repaired. At the minimum, the last calibration report (see Exhibit B) from that one that is presently applicable shall be maintained on file.

6.2.2 Each DC yoke shall be able to lift a standard weight of at least 40 lb (18 kg) at minimum 6 inch pole spacing for minimum of 3 seconds. This calibration shall be verified every year or whenever the electromagnetic yoke is suspected to have been damaged or after being repaired. At the minimum, the last calibration report (see Exhibit B) from that one that is presently applicable shall be maintained on file.

6.2.3 Each permanent yoke shall be able to lift a standard weight of at least 40 lb (18 kg) at the maximum pole spacing that will be used. This calibration shall be verified daily prior to use. This check doesn’t have to be maintained on file.

6.3 Calibration of Visible Light MeterVisible light meter shall be calibrated at least once a year or whenever the meter has gone through major repair. If meters have not been in used for one year or more, calibration shall be done before being used. At the minimum, the last calibration report from the one that is presently applicable shall be maintained on file.

7. EXAMINATION PROCEDURE

7.1 Viewing ConditionsA minimum light intensity of 100 fc (1000 lx) is required on the surface to be examined to ensure adequate sensitivity during the examination and evaluation of indications.

7.2 Surface Contrast EnhancementNonmagnetic coatings shall be applied temporarily to uncoated surfaces only in the amounts sufficient to enhance viewing contrast. The material used as contrast enhancer shall be of the white paint type and shall follow those specified in Table 1 for each particle manufacturer. After surface preparation in accordance with Par. 5, shake the contrasting paint to ensure uniform distribution of particles. Apply a uniform thin film of the contrasting paint to the test surface. Wait at least 30 seconds to allow the contrasting paint film to dry. Apply magnetic particles to the test surface.

7.3 Method of Examination



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Examination shall be done by the continuous method; that is, wet magnetic particles applied from the aerosol spray cans may be applied before and/or after magnetizing current is applied. Accumulation of excess particles in examination shall be removed by blowing or other source of low pressure dry air. The examination current or power shall be maintained for at least 3 seconds while removing the excess particles. Observe any indications formed.

Figure 1 – Yoke Placement and Orientation for Detection of Flaws [in mm]

7.4 Direction of MagnetizationAt least two separate examinations shall be performed on each area. During the second examination, the line of magnetic flux shall be approximately perpendicular to those used during the first examination. Fig. 1 shows example of typical yoke placement, poles configuration and orientation for detection of flaws.

7.5 Magnetizing Field Adequacy and DirectionAll examinations shall be conducted with sufficient overlap to assure 100% coverage at the required sensitivity. Yoke’s overlap shall not exceed that detailed in Fig. 1. Verification of magnetic field adequacy due to reduction of contact surface between the yoke leg and the part, a magnetic flux strip indicator (Burmah Castrol Type 1 containing three artificial defects) shall be used. Attach one flux indicator on the part surface under examination so that its length is at right angles to the direction of the applied flux. Magnetize the work piece by the use of the same pole spacing and contact area as the ones to be used for the examination. The magnetization time shall not be less than 3 seconds. While the work piece is being magnetized apply the magnetic particles. It is essential that the application of magnetic particles stops before the end of magnetization.



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The direction and field adequacy of the induced magnetic field is seen readily from the response of the flux indicators. The exact direction can be checked by re-orientating the indicators with respect to the direction of the field. The direction and field adequacy are considered sufficient when 3 (three) lines on the strip are clearly defined.

7.6 Evaluation of Indication(s)Discontinuities are indicated by retention of the examination medium. However, localized surface irregularities due to machining marks, magnetic permeability variations such as at the edge of heat affected zones or other surface condition may produce non-relevant indications. Broad areas of particle accumulation, which might mask indications from discontinuities, are prohibited, and such areas shall be cleaned and reexamined.

8. ACCEPTANCE STANDARDS

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.

8.1 Terminologies used in magnetic particle examination under this procedure are as follow:a. Only indications which have major dimension greater than 1.5 mm shall be considered

relevant.b. A linear indication is one having a length greater than three times of the width.c. A rounded indication is one of circular or elliptical shape with a length equal to or less

than three times its width.

8.2 For welds and its heat-affected zone, all surfaces examined shall be free from:a. Relevant linear indications.b. Relevant rounded indications greater than 5 mm.c. Four or more relevant rounded indications in a line separated by 1.5 mm, or less (edge

to edge).

8.3 Acceptance criteria for materials:All surfaces examined shall be free from any crack or crack-like indications.

9. EXAMINATION OF AREAS FROM WHICH IMPERFECTION HAVE BEEN REMOVED

Upon request, the area in which the defect has been removed (prior to making weld repairs) shall be re-examined in accordance with this procedure to ensure that the defect has been removed or reduced to acceptable size of imperfection.

10. RE-EXAMINATION OF REPAIRED AREA

After the weld is completed and the surface has been smoothly finished, the re-examination of repaired area shall be performed in accordance with this procedure.

11. DEMAGNETIZATION

Unless specified in the contracting documents, demagnetization is not necessary to be done. If the part is to be heat treated after examination, it is also not necessary to conduct demagnetization of the part previously examined.

12. POST EXAMINATION CLEANING

Unless directed otherwise by contracting documents, all parts and objects that have been examined by magnetic particle method are not necessary to be cleaned. When required by contracting document, post examination cleaning should be conducted as soon as practical using a process that doesn’t adversely affect the part. Typical post examination cleaning employed are:- Drying of wet particles and subsequent removal by brushing or with compressed air.- Removal of wet particles by flushing it with acetone.



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13. EXAMINATION REPORT

All relevant and rejectable indications shall be recorded. As a minimum, the type of indications (linear or rounded), location and extent (length or diameter or aligned) shall be recorded on Magnetic Particle Examination Report form as shown in Exhibit A of this procedure. The record shall be stored for a period as specified in the contracting documents.

14. SAFETY PRECAUTIONS

14.1 Care shall be exercised during examination for magnetic particle materials which are relatively toxic and highly flammable.

14.2 Manufacturer’s directions shall be followed at all times.

14.3 Smoking is prohibited while performing magnetic particle examination.

14.4 Electrical hazards like opened electrical wire from lighting source or magnetizing equipment and the presence of short circuiting medium shall be treated with care.

14.5 Material Safety Data Sheet (MSDS) for each magnetic particle materials shall be consulted in determining the proper method for the disposal of used pressurized spray cans and liquid residue waste.

Exhibit A – MAGNETIC PARTICLE EXAMINATION REPORT FORM



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MAGNETIC PARTICLE EXAMINATION REPORT Job/Contract No. : Report No. :

Project : Ref. Drawing No. :

Customer : Illumination Level :

Type of Magnetizing Current : Lighting Equipment :

Magnetizing Equipment : Serial No. :

Contrasting Paint : ……………….. Material Examined :

Particle Type & Manufacturer : Wet Non-Fluorescent ( ) Wet Fluorescent ( )

Dry Non-Fluorescent ( ) Dry Fluorescent ( )

Surface Condition : As Welded Ground Flush Other ( )

Magnetizing Method : Continuous Residual Other ( )

Stage of Examination : After Welding After Excavation Other ( )

Welding Process : SMAW GTAW Other ( )

Scope of Examination : Base Material Edge Preparation Procedure Reference :

Weldment Other ( ) Acceptance Standard :

Part Identification Joint No. Welder Code

Length examined

Type of Discontinuity

Result Remark

SKETCH

Examined By, Reviewed /Witnessed by Reviewed /Witnessed by Reviewed /Witnessed by

NDE Level __ Date : Client Representative Authorized Inspector Third Party

Exhibit B – ELECTROMAGNETIC YOKE CALIBRATION REPORT FORM



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PERIODIC CALIBRATION OF ELECTROMAGNETIC YOKES

Yoke's make and model :

Yoke's serial no. :

Referenced weight standard ID :

YOKE'S LIFTING POWER TEST RESULT

POWER SOURCE REFERENCED WEIGHT

POLE SPACING LIFTING TIME

RESULT

This is to confirm that the instrument above meets the requirement of PT. Inti Mutu Sejahtera Nusantara Document No.: IMSN/MT/17 Revision 0

Calibrated by :

Date of Calibration :

Next recommended calibration :

MT Procedure for Above Ground Storage Tank Rev. 0

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