Eddy Current RFT Procedure

 

 

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Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

NDT.TP.701.ET.03.Ry 

RFT Eddy Current Testing Procedure  NDT.TP.701.ET.03.Ry  

ate   Effective Date eviewed By  Prepared By  R eviewed itle   Title

ASNT Level III 

Technical  Manager 

ame   Name

Muhammad Kashif  

ajjad   Amir Sajjad

A pproved By  Lab Manager/ Quality Manager  

Sign ign  

Issue No.  1.0 

Issue Date  November.2015 

Revision No.  A.00 

17.November.2015   o.   istribution   Copy No. Distribution Deputy of GMO  1  Lab Manager   2  3  4 

Quality Manager   Technical Manager  

5 

SAC 

Issue By Quality Manager 

Page 1 of 12 

 

 

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Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

NDT.TP.701.ET.03.Ry 

Table of Contents  No. 

tem   Item

age   Page

1.  1. 

Table of Contents  Contents 

2 

2.  2. 

Amendment Page  Page 

3 

3.  3. 

Purpose  Purpose 

4 

4.  4. 

Scope  Scope 

4 

5.  5. 

Responsibilities  Responsibilities 

4 

6.  6. 

References  References 

4 

7.  7. 

Pre-Requisites  Pre-Requisites 

5 

8.  8. 

Definitions/Abbreviations  Definitions/Abbreviations 

5 

9.  9. 

Limitations  Limitations 

6 

10.  10. 

Equipment & Accessories  Accessories 

7 

11.  11. 

System Calibration  Calibration 

9 

12.  12. 

Examination & Recording Recording  

10  10 

13.  13. 

Acceptance Criteria  Criteria 

11  11 

14.  14. 

Report & Record  Record 

11  11 

15.  15. 

Recording Criteria  Criteria 

11  11 

16.  16. 

Analysis Criteria Criteria  

11  11 

16.  16. 

Revision Page  Page 

12  12 

Issue No.  1.0 

Issue Date  November.2015 

Revision No.  A.00 

Issue By Quality Manager 

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Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

NDT.TP.701.ET.03.Ry 

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1.

Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Currentt Testing  Remote Field Eddy Curren

NDT.TP.701.ET.03.Ry 

Purpose:  The purpose of this procedure is provide guidelines to NDT personnel of Motabaqah to carrying out Remote Field Testing (RFT) for the detection and locate of tube wall thinning and localized wall loss in the straight ferromagnetic tubes.  tubes. 

2.

Scope: This Procedure is applicable for RFT to detect tube wall thinning and localized wall loss ferromagnetic tubes of diameter ranging from 12.70  –  50.80   50.80 mm and thickness in 0.71 to 3.40 mm. This procedure is specifically applicable to RFT examination using an internal coil assembly for straight tubes excluding U-bend. This practice does not establish tube acceptance criteria, the tube acceptance criteria must be specified by the using parties/plant/cli p arties/plant/client. ent. 

3.

Responsibilities: 3.1 3. 1

3.2

4.

5.

ASNT NDT Level III Electromagnetic Testing is responsible to prepare the procedure and Technical Manager or his designee is responsible for review, explanation and modification of this procedure Quality Manager NDT and Deputy General Manager Operation are responsible to review & approve the procedure. Quality Manager NDT will also help/assist for its effective implementation.

3.3

ET level – 1 qualified person shall perform inspection according to approved procedure except analysis of results under supervision of ET Level II or III

3.4

ET level – II II or higher qualified qualified person can perform inspection inspection including including interpretation, interpretation, analysis and evaluation of the results.

References:  4.1. 4.1.   SNT-TC-1A

Recommended practice for Personnel qualification & certification in Non Destructive Testing 

4.2.   ASME Section V, 4.2. Article 17

Electromagnetic Testing , Remote Field Testing of ferromagnetic tubes  tubes 

4.3.

ASTM E-2096 

Standard Practice for In Situ Examination of Ferromagnetic Heat Exchangers Tubes using Remote Field Testing.  Testing. 

4.4.

ASTM E 543 

Practice for Agencies Performing Nondestructive Testing

4.5.

ASTM E1316

Terminology for Nondestructive Examinations

Pre – Requisites:  5.1 5. 1 Prior to remote field testing a reference standard shall be manufactured for the specific test of the same nominal size and material (chemical composition & product form) as that to be examined. The intent of this reference standard is to establish and verify system response. Reference standard for tubes in remote field testing shall be manufactured as per ASTM E 2096. Issue No.  1.0 

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NDT.TP.701.ET.03.Ry 

5.2

The tubes should be cleaned and dried by client before the start of inspection. The tubes should be free from water, scale and mud. 

5.3.

The inspection should be carried out after proper cleaning

5.4

Scaffolding and other arrangement needed to gain gain access to the required points of

5.5  

inspection will be arranged by client. Power supply, air supply, lighting arrangement 24V and electrical earthing /ground should be provided by the client.

5.6

6.

Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

Client should brief the inspector involved in the implementation of this procedure regarding the operation/accident history which later on will enable analyst for accessing the tube damage/condition. tube damage/condition.  

Definitions / Abbreviations:  6.1.  QC:  6.1.  QC:  Quality Control  Control  6.2.   ET:  ET:  6.2.

Electromagnetic Testing  Testing 

6.3. 6.3.   RFT:  RFT: 

Remote Field Testing, a nondestructive test method that measures

6.4. 6.4.   NDTIL:  NDTIL: 

changes in the remote field to detect and characterize discontinuities.  discontinuities.  Non-Destructive Testing & Inspection Lab  Lab 

6.5.   ASTM:  ASTM:  6.5.

American Society for Testing and Material  Material 

6.6. 6.6.   NDT:  NDT: 

Non-Destructive Testing Testing  

6.7. 6.7.   ASME:  ASME:      6.8. Frequency:

American Society of Mechanical Engineers  Engineers 

  6.9. Nominal Point:

The number of cycles per second of alternating electric current induced in the tubular product p roduct A point on the phase-amplitude diagram representing data from nominal tube.

6.10

Phase-Amplitude: A two-dimensional representation of detector output voltage, with   angle representing phase with respect to a reference signal, and radius representing amplitude. 6.11. Indications:  Eddy current signals caused by any change in the uniformity of a tube.   These changes in uniformity affect the electric e lectric characteristic of the tube 6.12. Sensitivity Control:  The control in the instrument which adjusts the amplifier gain and is   one of the factors that determines the capacity to detect discontinuities 6.13. Reference A piece of same material, dimensions and heat treatment condition Standard: with artificial discontinuities used for establishing the test sensitivity setting, periodically checking and adjusting sensitivity setting as required. Issue No.  1.0 

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Technical Procedure  otabaqah   Non Destructive Testing & Inspection Laboratory - Motabaqah Remote Field Eddy Curren Currentt Testing 

6.14.  Non-Quantifiable  Indication:  6.15. End Effect: 

NDT.TP.701.ET.03.Ry 

A non-quantifiable indication is a reportable indication that cannot be characterized. The indication shall be considered a flaw until resolved future inspections or otherwise The losses in sensitivity to discontinuities located near the extreme ends of the tube as test coil enter or leave the ends of the tube.

7. Limitations:   7.1.

Applicable to ferromagnetic tubes only. 

7.2.

Sensitive to surface variations therefore, requires smooth & clean surface

7.3.

Indication near tube sheet or edge may not be classified due to end effect.

7.4

Combination of defects on circumference circumference has to be approximated approximated due to to net change change in magnetic field of the test circuit

7.5

Any indication which remains unresolved shall be reported as non-quantifiable indication until resolved in future inspections or otherwise.

7.6

A reference reference standard is required required for system system calibration else the examination cannot be performed.

8. Equipments & Accessories: 8.1.

Instrumentation: 8.1.1 8. 1.1 The electronic instrumentation shall be capable of creating exciter signals of one or more frequencies appropriate to the tube material 8.1.2 The apparatus shall be capable of phase and amplitude analysis of detector outputs at each frequency, independent of other frequencies in use simultaneously. 8.1.3 The instrument shall display data in real time and recording data and system settings in a manner that allows archiving and later recall of all data and system settings for each tube 8.1.4 The data acquisition and analysis will be carried out by the following equipment:  Apollo Multi-Channel / Multi-Frequency RFT System 

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Inputs  Probe Inputs 

:8 8  

Channels  Channels 

: 8 simultaneously  simultaneously 

Number of frequencies  frequencies 

:4 4  

Gain Range  Range 

: 0 to 40GB  40GB 

Frequency Range  Range 

: 1 Hz to 10MHz  10MHz 

Probe Balancing  Balancing 

: Electronic probe balancing (hardware null)  null) 

Manufacturer  Manufacturer 

: GE Measurement & Control, USA  USA 

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NDT.TP.701.ET.03.Ry 

 

8.2.

RFT Probe:  The probes should be of an appropriate configuration and size for the tube being examined and compatible with the testing equipment.

8.3

RFT Tube Reference Standard: 8.3.1 8. 3.1

RFT tube standards should be of the same nominal dimensions, material type and grade as the tubes to be examined.

8.3.2

Typical artificial flaws and flaw characterization standards are as under:

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Technical Procedure  otabaqah   Non Destructive Testing & Inspection Laboratory - Motabaqah Remote Field Eddy Current Testing 

8.3.3

NDT.TP.701.ET.03.Ry 

The RFT system reference reference standard standard has specific artificial flaws. It is used to set up and standardize a remote field system and to indicate flaw detection sensitivity. The artificial flaws for the RFT system reference standard are as follows:  e qual Through-Hole: A through-hole (Fig. 1, Flaw A) whose diameter is equal to the tube wall thickness multiplied by a specified factor. For tubes of outside diameter less than 1.000 in. (25.40 mm), the factor is 1. For tubes of outside diameter greater than or equal to 1.000 in., the factor is 1.5. 

Flat-Milled Flaw: A flat-milled flaw (Fig. 1, Flaw B) of a depth of 50% and axial length one half of the tube nominal outside diameter. The flat should be side milled using a milling tool of a diameter of 0.250 in. (6.35 mm) to create rounded corners.  Short Circumferential Groove: A short circumferential groove (Fig. 1, Flaw C) of a depth of 20% and axial length of 0.625 in. (15.88 mm). Edges shall be angled at 105 degree.  Wear Scar: A simulated wear scar from a tube support plate (Fig. 1, Flaw D) consisting of a circumferentially tapered groove, 40% deep, extending over 180 deg of the tube circumference. Axial length measured at the bottom surface of the flaw shall be 0.625 in. (15.88 (1 5.88 mm). Edges shall be angled at 105 degree . Tapered Flaw: tapered flaw simulating near-tube-support erosion (Fig. 1, Flaw E) consisting of a groove 60% deep tapered circumferentially and in both directions axially, the steep side of the flaw shall be angled at 65 deg to the tube axis. The shallow side of the flaw shall be axially tapered so that it extends an axial distance of four tube diameters from the deepest point. The circumferential extent at the maximum point shall be 90 deg.  Long Circumferential Groove: A long circumferential groove (Fig. 1, Flaw F) of a depth of 20% and recommended axial length of two tube diameters, Length is optional according to application, Edges shall be angled at 105 degree  degree  Note: See figure 1, on next page

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Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

NDT.TP.701.ET.03.Ry 

IGU URE-1 -1:: M anufacturing Refer enc e fo r R F T S y s t e m R e f e r e n c e Sta Standa darrd  FIG

9.

System Calibration:  Ne xt page   System calibration shall be performed as below and according Figure-2, given on Next 9.1.

Differential Channels:  The phase rotation of the base frequency (F1) shall be adjusted so that the signal from the through-wall hole (TH) appears approximately along the Y (vertical) axis and that the signal from the tube support plate (TSP) lies in the upper left-hand and lower lowe r right-hand quadrants. When properly adjusted, the differential signals should be displayed on a voltage plane display  display 

9.2.

Absolute Channels:  The absolute channels should be calibrated by setting up the tube support/baffle plate signal at zero degrees de grees (horizontal at X-axis), While keeping the grove vertical upwards.  upwards. 

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NDT.TP.701.ET.03.Ry 

required for differential and absolute absolute channels channels Figure-2: The following settings are required calibration   calibration

10. Examinatio Examination n and Recording: 10.1. Scanning Direction:  Data shall be recorded as the probe traverses the tube. The data may be gathered in a “Timed” mode.  mode.   10.2. Scanning Speed:  The probe speed shall be dependent on the base frequency and sample rate and shall be no faster than the speed required obtaining a clear signal from the reference tube standard.  standard.  10.3. Tube Sheet Marking: The tube number shall be marked on the tube sheet as Rows and Columns or if available additional info of zones and flow passes.  Issue No.  1.0 

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10.4.

Technical Procedure  Non Destructive Testing & Inspection Laboratory - Motabaqah otabaqah   Remote Field Eddy Current Testing 

NDT.TP.701.ET.03.Ry 

Pull/Push Method: Manual push/pull by hands shall be utilized for inspection.

10.5. Recording of Signals:  The recording of remote field signals shall be done while pulling the probe through the tube. The tube number will be noted. The signals on storage device (hard disk) should be saved.  saved.  11.

Acceptance Criteria Criteria::   This procedure does not establish e stablish tube acceptance criteria; the tube acceptance criteria must be specified by the using parties/manufacturer/plant/client parties/manufacturer/plant/client..

12.

Report and Record: At the end of the inspection and data analysis a report will be filled by inspectors and analyst on the specific duly signed by Technical Manager. Report shall be kept as record in file.  file.  

13.

Recording Criteria:  Location of indication will be reported along the length of the tube with respect to support plates and depth range of the indications through the tube wall and wall thinning should be reported.   reported.

14.

Analysis Criteria:  The maximum evaluation depth of flaws and tube wall thinning shall be analyzed in terms of percentage. When the loss of tube wall is less than 20% the exact percentage of tube wall loss need not to be recorded and reported  reported 

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Revision Page 

Revised by: Job:  Date: Signature:  

Revised by: Job:  Date: Signature:  

Revised by: Job:  Date: Signature:  

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