1. PROCEDURE
FOR
MAGNETIC PARTICLE TESTING FOR PRESSURE VESSEL, BOILER AND PIPING
(Yoke Technique)
Document No : ExWI-NDT- 824 Page : 1 of 11 Revise No: 01 Issue Date: January 27, 2020
Prepared By Reviewed By Approved By
Signature
Name Mr. Sudhir Kumar Pantagani Mr. Sorrawut Sarncharoen Mr. Sorrawut Sarncharoen
Position NDT Level III NDT Level III NDT Level III
Sign Date January 27, 2020 January 27, 2020 January 27, 2020
Assigned to client Copy No. Total Page
11
Correction History
01 January 27, 2020 Revised to ASME 2019 Edition
00 April 27, 2016 First Issue
Revise No. Revise Date Description

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TABLE OF CONTENTS
1.0 SCOPE 3
2.0 PERSONNEL 3
3.0 REFERENCE 3
4.0 EQUIPMENT AND CONSUMABLE MATERIALS 3
5.0 PROCEDURE 4
6.0 INTERPRETATION 5
7.0 EVALUATION 5
8.0 ACCEPTANCE STANDARDS 5
9.0 REPAIRS 5
10.0 RE-TESTING OF REPAIR AREAS AND DEMAGNETIZATION 5
11.0 POST CLEANING 6
12.0 DOCUMENTATION 6
ATTACHMENT NO. I: Magnetic Particle Testing Report 7
ATTACHMENT NO. II : Acceptance Criteria 9

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1.0 SCOPE
1.1 This Testing method shall be used to inspect the surface of ferromagnetic
materials for welds and heat affected zone using AC Yoke with only wet magnetic
particle and visible type.
1.2 If the configuration of the surface does not permit this method, use a liquid
penetrant examination method.
1.3 Material shape(s) and size(s) to be examined refer construction drawing.
2.0 PERSONNEL
2.1 Personnel performing this testing shall be qualified in accordance with Qualitech
Written Practice, which is in accordance with the guidelines of the SNT -TC-1A or
equivalent.
2.2 Personnel certified to at least a Level II, who meet the requirements of Appendix
6, item 6-2 of Division I of the ASME Section VIII Code or equivalent, shall
perform, evaluate and report the testing.
2.3 Only individuals qualified for NDT Level II or Level III may perform
nondestructive testing
3.0 REFERENCE
3.1 ASNT Recommended Practice No. SNT-TC-1A, 2006 & 2016 Edition.
3.2 ASME Section V, Article 7 “Magnetic Particle Examination” 2019 Edition.
3.3 ASME SECTION I “Rule for Construction of Power Boilers” 2019 Edition.
3.4 ASME SECTION VIII Div.1 “Rule for Construction of Pressure Vessels” 2019
Edition.
3.5 ASME B31.1 “Power Piping” 2018 Edition.
4.0 EQUIPMENT AND CONSUMABLE MATERIALS
4.1 The magnetizing power of yokes shall be checked weight lifting power daily prior
to use each day as below
4.1.1 at least 10 lb (4.5 kg.) at the maximum pole spacing, with contact similar to
what will be used during the examination.
4.2 Typical magnetic particle materials to be used with this procedure are:
Item Manufacture Trade Name Magnetic Ink White Contrast
1 Sherwin Incorporated DUBL-CHEK Black Oxide No.1 CP-2
2 MR-Chemie GmbH Marker MR 76S MR 72
3 Magnaflux Spot Check 7 HF WCP-2
4.3 The magnetic particle shall be a color that provides adequate contrast with the
background of the surface being examined.
4.4 For visible magnetic particle
4.4.1 White acrylic or enamel paint shall be used as background as necessary.
4.4.2 Light source, flash light or spot light, shall be used if light intensity less
than 100 fc (1,076 Lux)
4.3.3 Light meter

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Light meter shall be calibrated at least once a year or whenever a meter
shall have been repaired. If meters have not been in use for one year or
more, calibration shall be done before being used.
5.0 PROCEDURE
5.1 Prepare, clean and dry the surface to be examined and any adjacent area within
at least 25 mm.
5.1.1 Remove surface irregularities and materials such as sand, loose rust and
loose scale from the surfaces to be examined . As-welded, as-cast, as-
rolled, and as-forged conditions are satisfactory.
5.1.2 Remove oil and grease by wiping with rags using light applications.
5.1.3 When used visible magnetic particle, if there is inadequate contrast
between the particle suspension and background of the surface to be
examined, apply a thin layer of white paint to the testing surface .
5.2 Provide adequate lighting for testing.
5.3 The temperature of the wet particle suspension and the surface being examined
shall be used within the temperature range limitations set by the manufacturer.
5.4 Place the yoke poles on the testing surface. Turn ON current when using an
electromagnetic yoke.
5.5 Wet magnetic particle: When using a prepared bath in an aerosol can or when
using a pressure's gun, squeeze hand gun or bottle dispenser, agitate the
prepared wet visible magnetic particles before each application to keep the
particles in suspension. Apply by spraying a small quantity over the surface
being examined.
5.6 After sufficient time for indications to form (minimum 5 second), observe particle
pattern for indications of discontinuities .
5.7 After inspection is complete, turn OFF current w hen using an electromagnetic
yoke.
5.8 Perform a second testing of the same area, per 5.4 through 5. 7 with the yoke
poles positioned at approximately right angle to the position of the yoke poles
during the first testing.
5.9 Re-position yoke poles for testing of the next area. Overlap sufficiently to assure
100% coverage of the area requiring testing.
5.10 After testing, the magnetic particle powder and the white paint on area examined
shall be cleaned.
5.12 When applied black magnetic particle is too much. The m ethod of excess particle
removal is removed all by wiping.

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6.0 INTERPRETATION
6.1 All indications shall be evaluated in terms of the ‘Acceptance Standards’ .
6.2 Mechanical discontinuities at the surface will be indicated by the retention of the
testing medium.
6.3 All indications are not necessarily defects; however, certain metallurgical
discontinuities and magnetic permeability variations may produce similar
indications, which are not relevant to the detection of unacceptable
discontinuities.
6.4 Any indication, which is believed to be non-relevant shall be regarded as a
defect and shall be re-examined to verify whether or not actual defects are
present. Surface conditioning may precede the re-testing.
6.5 Non-relevant indications, which would mask indications of defe cts, are
unacceptable.
6.6 For visible particle
6.6.1 The minimum light intensity of 100 fc. (1,000 lux) is required on the
surface to be tested to ensure adequate sensitivity during the testing and
evaluation of indications
6.6.2 The light intensity, natural or supplemental white light source, shall be
measured with a white light meter prior to the evaluation of indications or
a verified light source shall be used. Verification of light sources is
required to be demonstrated only one time, documented, and maintained
on file.
7.0 EVALUATION
7.1 All indications shall be evaluated in terms of the acceptance standards as
specified in clause 8.0.
7.2 Discontinuities at the surface will be indicated by retention of the testing
medium. However, localized surface irregularities due to machining marks or
other surface conditions may produce false indications.
7.3 Broad areas of particle accumulation, which might mask indications from
discontinuities, are prohibited, and such areas shall be cleaned and reexamined.
8.0 ACCEPTANCE STANDARDS
The acceptance criteria shall be as per the applicable design codes.
9.0 REPAIRS
10.1 When an imperfection is repaired by chipping or grinding and subsequent repair
by welding is not required, the excavated area shall be blended into the
surrounding surface so as to avoid sharp notches, crevices or corners .
10.2 When an imperfection is to be repaired by welding after the imperfection is
thought to have been removed and prior to making weld repairs, the area shall
be examined by the applicable steps in 5.0 to ensure it has been removed or
reduced to an acceptably sized imperfection.
10.0 RE-TESTING OF REPAIR AREAS AND DEMAGNETIZATION
Repaired areas shall be re-examined by the magnetic particle method and by all
other methods of testing that were originally required for the affected area, except
that, when the depth of repair is greater than the magnetic particle test sensitivity,
other testing methods shall be required. Demagnetization not require for yoke
technique.

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11.0 POST CLEANING
When post-cleaning is required, it shall be conducted as soon as practical using a
process that does not adversely affect the part.
12.0 DOCUMENTATION
13.1 Nonrejectable Indications. Nonrejectable Indications shall be recorded as
specified by the construction code.
13.2 Rejectable Indications. Rejectable Indications shall be recorded. The following
data, as a minimum, shall record in the report as shown in Attachment I of this
procedure.
(a) The type of Indications (linear or rounded)
(b) Location and extension (length or diameter or aligned)

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ATTACHMENT NO. I: Magnetic Particle Testing Report

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ATTACHMENT NO. II : ACCEPTANCE CRITERIA
ASME SECTION VIII Div.1

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ASME SECTION I

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ASME B31.1