REVISION CONTROL

Document No: BL019/FT/GEN

Procedure: FERRITE TESTING MEASUREMENT

Project: GENERAL

Location: CLIENT APPROVED LOCATION(S)

Rev Revision Details Date B.S.L

24/02/12
Rev 0 Issued for Comments
Rev 0 Issued for Production 01/03/12
Rev 0 Reviewed no updates required 27/05/21
Rev 1 Reviewed and updated 01/04/22
Rev 2 Reviewed and updated to include 01/07/24
ASTM Standards

Prepared By M. Covill Signature:

Approved By N. Youngs Signature:

ISSUED TO CLIENT BY QA/QC Dept.

NAME: SIGNATURE:

CLIENT NAME: DATE:

Doc. No. BL019/FT/GEN Rev. 2 Page 1 of 9

 TABLE OF CONTENTS

Contents
1. SCOPE...........................................................................................................................................................................3

2. NORMATIVE REFERENCES...................................................................................................................................3

3. TERMS AND DEFINITIONS.....................................................................................................................................3

4. PERSONNEL................................................................................................................................................................4

5. SAFETY PRECAUTIONS...........................................................................................................................................4

6. SYMBOLS AND DESCRIPTIONS............................................................................................................................4

7. GENERAL......................................................................................................................................................................4

8. PRINCIPLE..................................................................................................................................................................4

9. DESIGNATION............................................................................................................................................................5

10. EQUIPMENT................................................................................................................................................................5

11. NORMALIZATION AND CALIBRATION OF INSTRUMENT...........................................................................5

12. SURFACE PREPARATION.......................................................................................................................................5

13. FERRITE MEASUREMENT LOCATIONS.............................................................................................................6

14. TEST METHOD...........................................................................................................................................................7

15. HANDLING DURING MEASUREMENTS.............................................................................................................8

16. IDENTIFICATION AND MARKING.......................................................................................................................8

17. ACCEPTANCE CRITERIA........................................................................................................................................9

18. EVALUATION OF RESULTS....................................................................................................................................9

19. REPORTING..................................................................................................................................................................9

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 FERRITE EXAMINATION PROCEDURE

1. SCOPE
The object of this procedure is to provide a portable method (Field assessment) for ferrite content measurement,
expressed as a Ferrite Number (FN) or a ferrite percentage % (FP) in Austenitic and Duplex Ferritic-Austenitic
Stainless Steels, which will be followed whenever Ferrite content measurement is required on weld metal, clad
layers, surfacing, pipework, plate-work, items, welding consumables etc as categorised below to Meet
specification requirements using a Ferrite Scope.
a) Inspection of weldments, forgings, castings, wrought materials and weld overlays.
b) Determining ferrite levels within stainless steel welds, tubing’s and overlays both in the field and
laboratory settings.
c) Assess ferrite percentages for duplex stainless-steel pipe, tanks, castings, mechanical components.
d) Inspect regular construction steel that with austenitic chrome alloy steel welded cladding such as those
used in boilers, vessels, etc.
e) Inspection of weld materials including butt welds, category A-D welds, stainless steel weld overlays on
non-ferrous interfaces.
f) Welding consumables such as Stick electrodes, Solid wires, Flux-cored wires, and SAW wires etc.

2. NORMATIVE REFERENCES
References for this procedure have included BUT NOT LIMITED TO the latest editions of the following
Standards from ANSI, API, ASME, ASTM, AWS, BS EN ISO, NACE.
ANSI/NACE MR0103-2015/ISO 17945-2015, “Petroleum, petrochemical and natural gas industries – Metallic
materials resistant to sulfide stress cracking in corrosive petroleum refining environments”.
ANSI/NACE MR0175/ISO 15156 - Petroleum and Natural Gas Industries—Materials For Use In H2S-
Containing Environments In Oil And Gas Production.
ASME Section II Part A - BPVC Ferrous Material Specification.
ASME Section II Part C - BPVC Specifications for welding rods, electrode, and fillers metals.
AWS A4.2M – Standard Procedures for calibrating magnetic instruments to measure the delta ferrite content of
austenitic and duplex ferritic-austenitic stainless steel weld metal.
API 582 - Welding Guidelines for the Chemical, Oil, and Gas Industries.
API 938C - Use of Duplex stainless steels in the oil refining industry
BS EN ISO 17655 – Destructive tests on welds in metallic materials. Method for taking samples for delta ferrite
measurement.
BS EN ISO 15792-1 – Welding consumables – Test methods – Part 1: Preparation of all weld metal test pieces
and specimens in steel, nickel and nickel alloys.
BS EN ISO 8249 - Determination of Ferritics number in Austenitic Stainless Steel, Duplex and CrNi weld materials.
The Manufacturers Feritscope Operating Manual.

3. TERMS AND DEFINITIONS

For the purposes of this procedure the definitions listed below shall apply
3.1 All Weld Metal –
Filler metal that has solidified after welding and has not mixed with the parent metal.
3.2 Weld Metal –
Metal composed of parent metal and/or filler metal, or a metal deposited during surfacing.
3.3 Delta Ferrite -
Body centered modification of iron formed at high temperatures stable at ambient temperature.
3.4 Primary Weld Metal Standards -
Sample of carbon steel parent metal covered with non-magnetic layers of different thickness.
3.5 Secondary Weld Metal Standards -
Calibrated with primary weld metal standards.
3.6 Ferrite Number -
Measure of force required to detach a permanent magnet from austenitic metal sample (“tear-off force”
for short)
3.7 Ferrite Percent -
Percentage of delta ferrite in an austenitic material.

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4. PERSONNEL
a). All Bluelimit Surveys Ferrite Testing personnel shall have his/her vision with correction if necessary tested
to the requirements, of the ability, to read a Jaeger Type No. J1 Standard Chart at not less than 12" distance, and
have the capability of distinguishing and differentiating contrast between colours used. This shall be checked
annually.
(b). All Bluelimit Surveys Ferrite Testing personnel shall be experienced in Company Ferrite testing
procedures and techniques, to a level of training acceptable to Bluelimit Surveys Limited recognised standards.

5. SAFETY PRECAUTIONS
The Equipment shall be used in accordance with the manufacture’s equipment user’s handbook/manual.
All equipment shall be inspected for any obvious defects prior to use.
All health and safety procedures shall be always adhered to, appropriate PPE Shall always be worn.

6. SYMBOLS and DESCRIPTIONS

SYMBOL DESCRIPTION UNIT
FN Ferrite Number No.
FP Ferrite Percentage %
δ-ferrite Delta Ferrite No. or %

7. GENERAL
Austenitic weld metal may, as a function of its chemical composition and of the cooling conditions during the
welding process, contain a δ-ferrite phase. A certain amount of δ-ferrite is desirable to increase the resistance of
the austenitic weld metal to hot cracking; however, it also reduces corrosion resistance and promotes the
formation of a brittle sigma phase at elevated operating temperatures. Knowledge of the δ-ferrite content is a
necessity to allow the weld metal properties to be predicted, therefore the Feritescope shall be capable of the
following information.
 Provides precision measurements of ferrite content in austenitic and duplex steel.
 Suitable for measurements according to the Basler Standard or according to BS EN ISO 8249.
 Provides non-destructive measurement of ferrite content from 0.1 to 110 FN or 0.1 to 80% Fe in
austenitic and duplex steel.

8. PRINCIPLE
8.1 The equipment employs the magnetic induction test method whereby the ferrite content is obtained from
magnetic permeability.
Note: δ-ferrite is magnetic, whereas austenite, carbides, sigma phase and inclusions are non-magnetic.
8.2 The term “ferrite number” (FN) is used to designate the δ-ferrite content. The ferrite number is determined by
measuring the attractive force between a permanent magnet of a defined strength and size and steel samples with
electroplated non-magnetic coatings of different thickness.
Note: When low levels of δ-ferrite content are evident (below 10%); the ferrite number is not necessarily
identical to the percentage ferrite content of the weld metal.
8.3 The probe for ferrite content measurement consists of an iron core around which an exciter coil is wound. A
low-frequency (168 Hz) alternating current flows through this coil, this creates an alternating magnetic field
around the poles of the iron core. When one of the probe’s poles approaches the steel part, the grains of ferrite in
the steel automatically strengthen the alternating magnetic field, the measuring coil registers this increase as
voltage. The difference in the rise of the voltage depends on the magnetizable component in the crystal
structure. For this reason, this method cannot differentiate between delta ferrite and deformation martensite.
(See Figure 1)
Fig 1 Principle of the measuring instrument

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9. DESIGNATION
The value of ferrite number (FN) or ferrite percentage (FP) as determined in accordance with BS EN ISO 17655
shall be designated and reported on the Ferrite Measurement Report. This shall be as follows, the measurement
taken which relates to a measured value of 8; Shall be entered as Measurement 8FN.

10. EQUIPMENT
The Test equipment shall be the Fisher Feritscope FMP30 or DMP30, which gives a digital read out of the value
in either % Fe or FN and is capable in application of the following provisions: -
a). To measure within the specified range of 10-80% ferrite detection
b). To cope with the range of surface curvatures and orientations stated in section 12 of this procedure.
c). Is sufficiently portable to gain access for each check point under evaluation.
d). Capable of providing direct readout quantative results
e). Applicable calibration Blocks which cover the range of 10-80% Ferrite detection.
f). Where material thickness is less than 2.5mm a correction factor from the operating manual shall
be applied.

11. NORMALIZATION AND CALIBRATION OF INSTRUMENT

The Fisher ferrite scope has 3 levels of calibration and is supplied with two calibration blocks in low and high
ranges.
11.3 Master Calibration
Shall be carried out annually or when a repair as been carried out.
Press zero now place the probe on base then press enter now place the probe on the test block range whatever
we are going to test on the job. the test blocks range
11.4 Calibration Verification Method
Carrying out a instrument verification check. While switched off connect the probe of the analyzer with the
arrow aligned to the meter. Switch on the ferrite meter and go to APPL No. select FN or % Select applications
standard. Now take a reading from the base of the reference block ensuring thorough calibration is made to the
exact range of ferrite being measured. The result of this test should be 100% or over or have a ferrite number
(FN) of 140 with an error of no more than ±1. If this is not the case than the equipment should not be used. Now
the machine is ready for use.
11.5 Corrective Calibration
A corrective calibration of the equipment shall be performed whenever batteries, probe, cable etc. are replaced.
11.6 Measurement Factors
Measurement influencing factors do not significantly affect the instrument. Ferrite content measurements can be
carried out regardless of the substrate material properties starting at a plating thickness of 3 mm. Ferrite
measurements shall be corrected when thin or curved materials are inspected. The correction factor shall be
done using correction curves given in the operating manual.
a) Curvature of the sample for measurement
b) Thickness of the sample for measurement
c) Layer thickness
d Distance of the measuring position to the edge.
11.7 Correction factor to be applied.
Corrective calibrations with customer-specific calibration standards or correction factors (included) can be used
to take influences of the specimen shape (strong curvature), plating and substrate thicknesses into account. The
calibration is always stored measurement-application specific in the respective application memory.

12. SURFACE PREPARATION

12.1 General
12.1.1 The surface condition of the locations to be measured shall be free of any foreign material, such as lubricants,
dirt, magnetic particles, including oxidation, and have no residual contaminants from scaling, coatings paints or
embedding remnants from contact with other materials, which may interfere with the test. It shall also be bright
smooth and sufficiently flat to ensure adequate coupling of the probe. On welds the surface shall be in the as
welded condition. (Image 1).

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 Image 1- Probe on finished surface’s.

FERRITE

13. MEASUREMENT LOCATIONS

Unless otherwise specified by the Client the following measurement location criteria shall be met.
13.1 In the case of all-metal weld, the measurements shall be taken at the centre of the weld bead, when measuring
small welds or a thin surface consisting of austenitic materials consider the characteristics of the instrument and
adjust accordingly.
13.2 Rolled, Wrought and Forged Products - Measurements shall be carried out in accordance with table 1
13.3 For Fittings Flanges Forgings and Bar see Table 1. For Valves Table 2 shall be applicable.

Table 1 -
Component NB of Component
D≤6” 6” <D≤12” D>12”
Pipe (note 7) 3 (notes 2 & 3) 3 (notes 2 & 3) 3 (notes 2 & 3)
Tee 1 (note 3) 4 (notes 2 & 3) 5 (notes 2 & 4)
Flange and Fittings 1 (note 3) 3 (notes 2 & 3) 3 (notes 2 & 3)
O’Lets 1 (note 3) 2 (note 4) 6 (note 5)
Forgings 2 (note 6) 4 (note 6) 4 (note 6)
Bars and Shapes 1 (notes 1 & 6) 2 (notes 1 & 6) 4 notes (1& 6)

Note 1 – Average of 3 test readings

Note 2 – at extreme ends plus 2 extra when component contains a weld.
Note 3 – Centre plus 1 extra when component contains a weld.
Note 4 – Centre on opposite sides.
Note 5 – Centre and extreme ends on opposite sides.
Note 6 – Thinnest and thickest part of item.
Note 7 – For Duplex stainless steel only weld metal testing is required base material my be omitted .

13.5 Table 2 - VALVES

NB of Valve Body
D≤2” 2” <D≤4” 4” <D≤12” D>12”
Body 2 (note 2) 6 (Note 3) 12 (note 4) 12 (note 4)
Bonnet 1 (note5) 1 (note 5) 3 (note 6) 3 (note 6)
Stem 1 (note 5) 1 (note 5) 3 (note 6) 3 (note 6)
Ball/Wedge/Plug 1 (note 5) 2 (note 2) 6 (note 3) 6 (note 3)

Note 1 – Average of 3 test readings

Note 2 – Centre on opposite sides.
Note 3 – Centre and extreme ends on opposite sides.
Note 4 – Centre and extreme ends at 4 quadrant positions.
Note 5 – Centre
Note 6 – Centre and on OD or end.

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 Note 7 – any welds in pressure parts shall be tested at the centre and at each end.
Note 8 – Wafer type valve to be tested at centre location only

13.6 Induction bends

Due to the manufacturing process of induction bends, the location and number of ferrite measurements shall
depend on the client requirements.

14. TEST METHOD

The FERITSCOPE® FMP30/DMP30 shall be used in accordance with this procedure to determine the ferrite
content or ferrite number of austenitic and DUPLEX steel and to determine the portion of deformation
martensite in austenitic materials.
14.1 Non-destructive measurement of the ferrite content in a range from 0.1 to 80 % Fe or 0.1 to 110 FN.
Ensure that the surface finish is in accordance with section 12 and ensure the test instrument has been calibrated
in accordance with 11.4 and the test location(s) have been marked up. The test can be carried out in
measurements of either ferrite number (FN) or percentage (%), to switch between these press the APPL No.
button and choose application 0 for percentage (%) or 1 for ferrite No. (FN).
14.1.1 Before operation check the instrument and probe for damage. Ensure that the battery is in good condition and
charged. Attach the probe to the instrument whilst it is still switched off.
Note: The instrument must always be in the off mode before disconnecting the PROBE.
14.1.2 Prior to testing, a reading shall be taken on the reference block. The result from this test should read 100% or
above, or have a ferrite number (FN) of 140 with an allowable error of ± 1 FN. If this is not the case the
instrument shall be taken out of service.
14.1.3 A verification check shall now be carried out and recorded on the appropriate standard form. The
calibration should be within ± 5 % of the stated value i.e. 87.1 Fe% ± 4.36 Fe%.
14.1.4 The verification Steps para 3.3 and 3.4 should be repeated every 4 hours during testing and once testing is
complete.

14.1.5 The tests can be carried out in measurements of either percentage or in ferrite number (FN). To switch between
the two, press the APPL No button on the instrument and choose application 0 for percentage or application 1
for ferrite number.
14.1.6 No metallic items shall be within 25mm of the probe tip when the instrument is turned on and in use, other than
the item being tested.
14.2 The dimensions of the item(s) shall meet these basic requirements:
14.2.1 The curvature diameter of a convex curvature of the specimen, see figure 3
14.2.2 The curvature diameter of a concave curvature of the specimen, see figure 4
14.2.3 The distance of the measurement location from the edge see figure 5 and 6.
14.2.4 The thickness of the specimen see figure 7
14.2.5 The cladding thickness see figure 7

Figure 1 - Probe Figure 2 – Probe approach and touch down details

Lift-off distance
between 2
measurements ≥ 8 mm
≥ 0.32 "

Deviation figures
Figure 3 – Influence of convex curvature Figure 4 - Influence of concaved curvature
Curvature (R), measurement deviation from nominal value Curvature (R), measurement deviation from nominal value with
with reference to a calibration on flat surface. Measurement reference to a calibration on flat surface. Measurement deviation ≥ 5 %
deviation ≥ 5 % for R ≤ 10 mm (R ≤ 0.39 ") Probe needs a for R ≤ 5 mm (R ≤ 0.2 "). Probe needs a minimum of R = 1 mm (support
minimum of R = 15 mm (support stand necessary) (R = 0.59 stand necessary) (R = 0.039 ")
")

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 Figure 5 – Circular edge distance measurement Figure 6 – Square edge distance measurement
Edge distance (R), specification from probe tip center, Edge distance (X), specification from probe tip center, measurement
measurement deviation from nominal value. deviation from nominal value.
Measurement deviation ≥ 2 % for R ≤ 3 mm (R ≤ 0.12 ") Measurement deviation ≥ 2 % for X ≤ 3 mm (X ≤ 0.12 ")
Probe needs a minimum of R = 5 mm (support stand necessary)
(R = 0.2 ")

Figure 7 – Material thickness measurement

Material thickness (D), measurement deviation from nominal value.
Metal sheet thickness D: Measurement deviation
≥ 10 % for D ≤ 1 mm (D ≤ 0.039 ")
Plating thickness D on iron or steel: Measurement

14.3 The instrument will automatically shut down after 5 minutes of non-use or can will shut down manually using
the ON/OFF switch.
14.4 The instrument can be used with or without plastic end cap.
14.5 Results will be recorded on the test worksheet and distributed to the relevant personnel.

15. HANDLING DURING MEASUREMENTS

15.1.1 Always hold the probe at its grip sleeve (Fig 8).
15.1.2 Place the probe lightly at a right angle on the test location holding the grip sleeve now push down until the
sleeve is in contact with the item (Fig 9).
15.1.3 Slide the grip sleeve to the specimen surface such that the sleeve rests on the specimen (Fig 9 & 10) once the
instrument as registered the reading an audible sound will be emitted and a reading will appear on the display
screen note this reading.,
15.1.4 Lift the probe off the specimen before making the next measurement.
15.1.5 Allow sufficient time for the measurement to be accepted by the instrument the time between individual
measurements shall be ≥ 2 seconds.
Caution
Make sure that no metallic items come within 25mm of the probe tip once switched on and when in use, other
than the item being tested. The testing unit can be used with or without the plastic end cap in place.
Avoid hard impacts.
Do not allow the probe to hover directly above the surface. Doing so will lead to erroneous readings.
To avoid breakage of the wiring, do not bend the probe connector cable! The radius of rolled up probe
connector cables should always be at least 50 mm
Note: The equipment will automatically shut down after 5 minutes of non-use.

Figure 8 Figure 9 Figure 10

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16. IDENTIFICATION and MARKING
a). All Failed items tested shall be suitably marked.
b). Any marking system required by the Client or any project specific requirements shall be down to the
Clients remit to provide.

17. ACCEPTANCE CRITERIA

The ferrite level of the item shall be accepted if it is within the ranges specified for the test being carried out.

18. EVALUATION OF RESULTS

If the measured readings at one location are outside the specified ferrite content range, two additional
measurements shall be taken in the vicinity of that measuring point.
If either of the additional measurements yields ferrite readings outside the specified ferrite content range the
product shall be rejected.
If the two additional measuring points give readings within the ferrite content acceptance range, a further
surface preparation shall be performed at that measuring location, and the measurement repeated, if acceptable
result are obtained the product shall be accepted.
The client shall specify the acceptance criteria as different standards have introduced different criteria for
allowable ferrite fraction in base metal, heat affected zone (HAZ) and weld metal.

19. REPORTING
All readings shall be the subject of a written report which shall be issued on completion of the examination.
The test report shall contain the following information
a). Client.
b). Client Reference Number.
c). Part Identification Number.
d). Date of Test.
e). Procedure Number and Revision Status.
f). Equipment Used.
g). Material Type.
h). Test results of item tested.
i). Inspectors name.

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