Magnetic Particle Testing Procedure
1.0 SCOPE:
This procedure describes the method for detection and evaluation of surface and sub surface flaws in ferromagnetic materials.
2.0 REFERENCE:
ASME Sec. V (Article 7 & SE 709 of Article 25),
ASTME E709 - Standard Recommended Practice for Magnetic Particle Examination.
ASME/ANSI B31.1 – Power Piping
ASME/ANSI B31.3 – Process Piping
ASME Sec.VIII DIV.I & 2
AWS D1.1
3.0 PERSONNEL QUALIFICATION:
The personnel performing examination shall be certified in accordance for qualification and certification of NDT personnel. SNA-TC-1A 2020
4.0 EQUIPMENT:
4.1 AC- electromagnetic yoke
The electromagnetic yoke used shall be Y6 type, Magnaflux, Parker or Equivalent, operating 110/240 volts with test lift capacity of 10lbs (4.5kg) mild steel.
4.2 DC Yoke
The equipment that shall be used is Y6 type Magnaflux, Parker or Equivalent with pole separation of 75-150mm (3” – 6”) and test lift capacity of 40lbs (18.0kg) mild
Steel.
5.0 CALIBRATION:
Lift check shall be carried out weekly in line with section 4.0 of this procedure. Record of the checks shall be maintained.
Field strength check shall be carried out using a Burmah Castrol Strip/Pie gauge prior to commencement of each working shift. Shall be used to check the field strength.
6.0 SURFACE CONDITION:
6.1 Preparation:
As welded surface with temperature maximum 35°C, is generally acceptable.
The surface irregularities shall not mask the indications from discontinuities. Otherwise, surface preparation by grinding or machining may be necessary. Undercuts, overlaps or abrupt ridges and valleys in the welds shall be smoothly merged with parent metal.
6.2 Prior to magnetic particle examination, the surface to be examined and any adjacent area within at least 25 mm of the surface to be examined shall be dry and free of any dirt, grease, lint, welding flux, spatter, oil or other extraneous matter that would interfere with the examination.
6.3 The prod tips shall be kept clean and dressed to minimize electrical arcing.
6.4 Cleaning may be accomplished by detergents, organic solvents, Paint removers, Grit or Sand blasting methods.
7.0 CONSUMABLES
Contrast paint shall comply the requirements of BS 5044, e.g. ARDROX 8901 w White emulsion paint or equivalent.
Magnetic Inks shall comply with the requirements of BS 5044, e.g. ARDOX 800/3 or equivalent.
8.0 TECHNIQUE:
8.1 Prepare examination surface and check equipment calibration and field strength in accordance with section 8.0 & 7.0 of this procedure.
8.2 Apply contrast paint on the examination surface in a thin even coat.
8.3 Apply magnetic field, then apply examination medium (ink) and allow excess to disperse whilst magnetic field remains applied (continuous magnetization.)
8.4 Observe and evaluate indications.
8.5 Repeat the examination in the same area by tilting the yoke about 90° to the initial examination.
8.6 Repeat the above examination sequence in adjacent area shall have an overalp of 10% to ensure adequate coverage.
8.7 Magnetizing Current:
The current shall be 100 (minimum) to 125 (maximum) amperes per 25mm of prod spacing for sections 19mm thickness or greater.
For sections less than 19mm the current shall be 90 to 110 amperes per 25mm of prod spacing.
9.0 DIRECTION OF MAGNETISATION:
At least two separate examinations shall be carried out on each area. During the second examination the lines of magnetic flux shall be approximately perpendicular to those used during the first examination.
10.0 EXAMINATION COVERAGE:
All examinations shall be conducted with sufficient overlap to assure 100% coverage.
11.0 VERIFICATION OF PERFORMANCE OF THE TECHNIQUE:
Verification of performance of the equipment shall be done before starting the examination and once in a shift on a specimen with known defects (test plate with grooves) on one side at different depths to ensure proper functioning of the test system. The indication of a groove at 3mm depth from the surface of the test plate will indicate adequate sensitivity.
12.0 DEMAGNETIZATION:
Demagnetization is normally not required, however if specified and required this shall be carried out.
13.0 INTERPRETATION OF INDICATION:
13.1 A minimum white light intensity of 1000 Lux (100 fc) is required to ensure adequate sensitivity during the examination and evaluation of indications.
13.2 Relevant Indication:
Relevant Indications are produced by Magnetic leakage fields, which are the result of mechanical discontinuities. Indications exceeding 1.6 mm size in any dimension shall be considered as relevant indications. All relevant indications shall be evaluated to the requirements of paragraph15.0.
13.3 Non-Relevant Indication:
Non Relevant Indications can occur singly or in patterns as a result of leakage fields created by conditions that require no evaluation such as changes in sections (like keyways and drilled holes), inherent material properties (like the edge of a bimetallic weld), Magnetic writing, etc.
13.4 False Indications:
False Indications are not the result of magnetic flux leakages. Examples are particles held mechanically or by gravity in shallow depressions or particles held by rust or scale on the surface. Areas showing false indications shall be retested.
13.5 Linear Indications:
A Linear Indication shall be defined as the one having a length greater than 3 times the width.
13.6 Rounded Indications:
A Rounded Indication shall be defined as the one of circular or elliptical shape with the length equal to or less than 3 times the width.
13.7 Treatment of Non-relevant Indications:
Any indication, which is believed to be non-relevant, shall be regarded as an imperfection unless it is shown by re-examination by the same method or by the use of other Non-Destructive methods and/or by surface conditioning that no unacceptable imperfection is present.
13.8 Acceptance Criteria:
The acceptance criteria shall be in accordance with client’s requirements.
However, unless otherwise specified the minimum acceptance criteria shall be in accordance with the latest editions of the following:
i) ASME Section- VIII Div. 1 & 2 for Pressure Vessels
ii) ASME / ANSI B31.1 – for Power Piping and
iii) ASME / ANSI31.3 – FOR Process Piping.
iv) AWS D1.1
14.0 POST CLEANING:
Post-test cleaning is necessary where magnetic particle materials could interfere with subsequent processing. The Client should specify when post cleaning is needed and the extent required.
Post-test cleaning shall be carried out using detergents, solvents, paint removers, grit blasting or wire brushing.
15.0 FINAL CLEANING:
When the inspection is concluded, materials shall be cleaned by dry cotton waste, leaving the product in a dry and a clean condition.
16.0 Reporting:
Magnetic Particle Inspection Report Format shall be used for preparing the
reports as required by code.
1.0 SCOPE:
This procedure describes the method for detection and evaluation of surface and sub surface flaws in ferromagnetic materials.
2.0 REFERENCE:
ASME Sec. V (Article 7 & SE 709 of Article 25),
ASTME E709 - Standard Recommended Practice for Magnetic Particle Examination.
ASME/ANSI B31.1 – Power Piping
ASME/ANSI B31.3 – Process Piping
ASME Sec.VIII DIV.I & 2
AWS D1.1
3.0 PERSONNEL QUALIFICATION:
The personnel performing examination shall be certified in accordance for qualification and certification of NDT personnel. SNA-TC-1A 2020
4.0 EQUIPMENT:
4.1 AC- electromagnetic yoke
The electromagnetic yoke used shall be Y6 type, Magnaflux, Parker or Equivalent, operating 110/240 volts with test lift capacity of 10lbs (4.5kg) mild steel.
4.2 DC Yoke
The equipment that shall be used is Y6 type Magnaflux, Parker or Equivalent with pole separation of 75-150mm (3” – 6”) and test lift capacity of 40lbs (18.0kg) mild
Steel.
5.0 CALIBRATION:
Lift check shall be carried out weekly in line with section 4.0 of this procedure. Record of the checks shall be maintained.
Field strength check shall be carried out using a Burmah Castrol Strip/Pie gauge prior to commencement of each working shift. Shall be used to check the field strength.
6.0 SURFACE CONDITION:
6.1 Preparation:
As welded surface with temperature maximum 35°C, is generally acceptable.
The surface irregularities shall not mask the indications from discontinuities. Otherwise, surface preparation by grinding or machining may be necessary. Undercuts, overlaps or abrupt ridges and valleys in the welds shall be smoothly merged with parent metal.
6.2 Prior to magnetic particle examination, the surface to be examined and any adjacent area within at least 25 mm of the surface to be examined shall be dry and free of any dirt, grease, lint, welding flux, spatter, oil or other extraneous matter that would interfere with the examination.
6.3 The prod tips shall be kept clean and dressed to minimize electrical arcing.
6.4 Cleaning may be accomplished by detergents, organic solvents, Paint removers, Grit or Sand blasting methods.
7.0 CONSUMABLES
Contrast paint shall comply the requirements of BS 5044, e.g. ARDROX 8901 w White emulsion paint or equivalent.
Magnetic Inks shall comply with the requirements of BS 5044, e.g. ARDOX 800/3 or equivalent.
8.0 TECHNIQUE:
8.1 Prepare examination surface and check equipment calibration and field strength in accordance with section 8.0 & 7.0 of this procedure.
8.2 Apply contrast paint on the examination surface in a thin even coat.
8.3 Apply magnetic field, then apply examination medium (ink) and allow excess to disperse whilst magnetic field remains applied (continuous magnetization.)
8.4 Observe and evaluate indications.
8.5 Repeat the examination in the same area by tilting the yoke about 90° to the initial examination.
8.6 Repeat the above examination sequence in adjacent area shall have an overalp of 10% to ensure adequate coverage.
8.7 Magnetizing Current:
The current shall be 100 (minimum) to 125 (maximum) amperes per 25mm of prod spacing for sections 19mm thickness or greater.
For sections less than 19mm the current shall be 90 to 110 amperes per 25mm of prod spacing.
9.0 DIRECTION OF MAGNETISATION:
At least two separate examinations shall be carried out on each area. During the second examination the lines of magnetic flux shall be approximately perpendicular to those used during the first examination.
10.0 EXAMINATION COVERAGE:
All examinations shall be conducted with sufficient overlap to assure 100% coverage.
11.0 VERIFICATION OF PERFORMANCE OF THE TECHNIQUE:
Verification of performance of the equipment shall be done before starting the examination and once in a shift on a specimen with known defects (test plate with grooves) on one side at different depths to ensure proper functioning of the test system. The indication of a groove at 3mm depth from the surface of the test plate will indicate adequate sensitivity.
12.0 DEMAGNETIZATION:
Demagnetization is normally not required, however if specified and required this shall be carried out.
13.0 INTERPRETATION OF INDICATION:
13.1 A minimum white light intensity of 1000 Lux (100 fc) is required to ensure adequate sensitivity during the examination and evaluation of indications.
13.2 Relevant Indication:
Relevant Indications are produced by Magnetic leakage fields, which are the result of mechanical discontinuities. Indications exceeding 1.6 mm size in any dimension shall be considered as relevant indications. All relevant indications shall be evaluated to the requirements of paragraph15.0.
13.3 Non-Relevant Indication:
Non Relevant Indications can occur singly or in patterns as a result of leakage fields created by conditions that require no evaluation such as changes in sections (like keyways and drilled holes), inherent material properties (like the edge of a bimetallic weld), Magnetic writing, etc.
13.4 False Indications:
False Indications are not the result of magnetic flux leakages. Examples are particles held mechanically or by gravity in shallow depressions or particles held by rust or scale on the surface. Areas showing false indications shall be retested.
13.5 Linear Indications:
A Linear Indication shall be defined as the one having a length greater than 3 times the width.
13.6 Rounded Indications:
A Rounded Indication shall be defined as the one of circular or elliptical shape with the length equal to or less than 3 times the width.
13.7 Treatment of Non-relevant Indications:
Any indication, which is believed to be non-relevant, shall be regarded as an imperfection unless it is shown by re-examination by the same method or by the use of other Non-Destructive methods and/or by surface conditioning that no unacceptable imperfection is present.
13.8 Acceptance Criteria:
The acceptance criteria shall be in accordance with client’s requirements.
However, unless otherwise specified the minimum acceptance criteria shall be in accordance with the latest editions of the following:
i) ASME Section- VIII Div. 1 & 2 for Pressure Vessels
ii) ASME / ANSI B31.1 – for Power Piping and
iii) ASME / ANSI31.3 – FOR Process Piping.
iv) AWS D1.1
14.0 POST CLEANING:
Post-test cleaning is necessary where magnetic particle materials could interfere with subsequent processing. The Client should specify when post cleaning is needed and the extent required.
Post-test cleaning shall be carried out using detergents, solvents, paint removers, grit blasting or wire brushing.
15.0 FINAL CLEANING:
When the inspection is concluded, materials shall be cleaned by dry cotton waste, leaving the product in a dry and a clean condition.
16.0 Reporting:
Magnetic Particle Inspection Report Format shall be used for preparing the
reports as required by code.