Ultrasonic Testing Procedure For Corrosion Mapping: Astron [PDF]

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ASTRON ULTRASONIC C-SCAN CORROSION MAPPING

Ultrasonic Testing Procedure For Corrosion Mapping Document Number

:

L3-AST-NDE-102

Date

:

01-03-2016

Revision Number

:

0

Prepared By

Reviewed By

Vijayarajan N ASNT-Level-II

Anbazhagan M ASNT-Level-III (UT) ASNT ID#245082

Approved By

Rajasimman M ASNT-LEVEL-III (MT,PT,RT,UT,ET) ASNT ID#195513

Procedure Change Rev 0

Date

Doc No.

Section

L3-AST-NDE-102

Description

Rev No.

Page 1 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING TABLE OF CONTENTS SR. NO. 1.0 2.0 3.0 4.0

DESCRIPTION

Page No.

SCOPE

4 4 4 4

PERSONNEL QUALIFICATIONS REFERENCES DEFINITIONS EQUIPMENT DETAIL

5.0

5.1 Ultrasonic Equipment 5.2 Probes 5.3 Mechanized Scanner 5.4 Storage of Data 5.5 Coupling Medium

6.0

4-5

Examination Surface and Surface Condition 5

6.1 Examination Surface 6.2 Surface Temperature 6.3 Condition

7.0

Calibration 7.1 Calibration Checks During Operation 7.2 DAC Compensation 7.3 Sensitivity Setting 7.4 Low resolution

8.0

6

Mapping 8.1 General 8.2 Normal Resolution 8.3 High Resolution 8.4 Low Resolution

9.0

6-7

Interpretation and Evaluation

7-8

9.1 Displaying the Result 9.2 Data Evaluation 9.3 Data Interpretation

10.0

Doc No.

8

Reporting

L3-AST-NDE-102

Rev No.

Page 2 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING 1.0 SCOPE

This procedure describes the preparation, execution of P-Scan examination and interpretation of the test results. This purpose of the examination is detection and reporting of wall thickness variation and or corroded areas in pipe geometry, in a thickness range between 4mm up-to 35mm and the pipe diameter range 4” to 48” assured from the probe position, dependent on the conditions and thickness of the pipe. Position and extent of indications from detected area reported in Astron AUT Format. 2.0

PERSONNEL QUALIFICATIONS

Examinations shall be carried out by operators qualified in accordance with PCN /EN 473 or ISO 9712 or equivalent standard as a minimum level 2, in addition the technicians shall be Adequately trained and experienced in the operation of the equipment (P-Scan 4L equipment) and in the interpretation of computerized inspection data. 3.0

    

REFERENCES

ASME BPV Code Section V) SP-1195 (Specification for the Wall thickness measurement of Pipelines by Automated Ultrasonic Techniques) ASME Section V (Nondestructive Examination) EN-473 (Standard for certification of NDT personnel) ISO 9712 (Non-destructive – Qualification and certification of Personnel)

4.0 DEFINITIONS

PCN - Personnel Certification in Non Destructive Testing ASNT - American Society of Non-destructive Testing PMC - Portable Motor Controller FBH - Flat bottom hole 5.0 EQUIPMENT DETAILS

5.1 Ultrasonic Equipment

The P-Scan 4L is an advanced ultrasonic imaging and analysis system. The software provided operates within a Windows 98/2000/XP with a resolution of XGA resolution (1024 X 768 pixels) environment and provides a fully integrated easy to use package for on-line and off-line analysis. Complete setup, control and analysis of collected data using standard Notebook

Doc No.

L3-AST-NDE-102

Rev No.

Page 3 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING The equipment shall be used in thickness imaging mode The wall thickness setting shall be always at nominal wall thickness plus 20% regardless of the real wall thickness of the object under examination. Wall thickness are programmed in color steps, the choice of color step is that the area of interest is fully covered & enough presentable for client. 5.2

Probes

Compression probes with an operating frequency normally within the range of 4MHz to 10MHz. Probes should be compatible with the P-Scan Equipment. Nominal wall thickness ≤5mm >5mm 5.3

Frequency 10 MHz 4-5 MHz

Mechanized Scanner

To enable storage of the Ultrasonic Data at the proper projected positions a scanner with adapted probe holders shall be used. The accuracy of the scan position shall be such that the maximum deviation of the registered position compared to the real position is less than the 25mm. For this procedure scanning mechanism shall be XY-scanner matching P-scan 4 Lite and Connects to the Scanner AUS-3. 5.4

Storage of data

During examination all Data shall be stored in internal hard disc. After inspection all data shall be stored on a permanent storage medium. The disc shall be used for data transfer and for comparison at future tests. 5.5

Coupling Medium Probe to component coupling is ideally achieved using water feed to P-Scan 4 Lite water pump DCP-4 probe attachment. However, use of the probe on small diameter piping and in areas with configuration restrictions may require the use of manually applied couplants such as Ultrasonic gel or Cellulose paste.

6.0

Examination Surface and Surface Condition 6.1

Examination Surface The examination surface of the object shall be free from dirt, loose scale, loose coating and rust. If the corrosion product or dirt is present the company shall arrange proper cleaning and primer coating of the examination area.

6.2

Surface temperature The examination surface shall not exceed the 60 Degree Celsius (140 Degree F). Doc No.

L3-AST-NDE-102

Rev No.

Page 4 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING

6.3

Condition For good coverage of the examination area the mechanized scanner must have enough space to pass through.

7.0 CALIBRATION

The A-scan display time base shall be calibrated to a scale compatible with the probe selection and material thickness under test, using a graduated step-wedge/ FBH Block 7.1

Calibration Checks During Operations

The equipment calibration shall be checked against calibration reference blocks regularly during shift and at every switch on of equipment prior to scanning. Actual plotted images should also be checked after the first scan is obtained following equipment switch on and shall be cross verified by Manual UT (A-Scan presenting equipment) Achieved accuracy of calibration is recorded along with other scan parameters and, in accordance with general acceptable ultrasonic practices, should be within a tolerance of ± 0.5mm. 7.2

DAC Compensation

No compensation curve (DAC) shall be programed 7.3

Sensitivity Setting The probe sensitivity is depending on the kind of examination and size of flaw detection. Basically the sensitivity shall be set on a reference block like a step wedge for wall thickness measurements or block with reference reflectors for corrosion mapping. The sensitivity shall be set in such way that the wall thickness or corrosion can be detected regardless of the signal variations of -14 dB The first back wall echo shall be set on 80% of full screen height (FBH) this signal shall be corrected for signal loss (Transfer correction) and block reflector size correction. The required sensitivity settings in relation to the wall thickness are listed in the following table: Nominal wall thickness ≤5mm >5mm

Doc No.

L3-AST-NDE-102

FBH 1 mm 2 mm

Rev No.

Page 5 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING 8.0 MAPPING

The center of scan location should be identified by any means (e.g. Dig sheet supplied by client) Scanning shall be mapped out as 8.1

8.2

General Nominal wall thickness

NR

HR

0 - 5mm 5mm – 12 mm 12mm & above

2X2 4X2 4X4

1X1 1X1 2X2

Normal Resolution

Scan 1 380mm X 100% circumferential ᴓ (12 O’clock to 12 O’clock) Scan 2 380mm X 50% Circumference ᴓ Scan should cover the area of defect as per dig sheet orientation Scan 3 380mm X 50% Circumference ᴓ Scan should cover the area of defect as per dig sheet orientation 8.3

High Resolution

After completion of 3 scans High resolution scan should be done at minimum thickness. 8.4

Low Resolution

This scan shall be performed in visual inspection area, in some areas the external surface defects cannot be found on those areas Low resolution scan shall be performed by 8 X 2 resolutions 9.0

Interpretation and Evaluation 9.1

Displaying the result All on disk stored data shall be transferred to the evaluation PC for further analysis. The result shall be displayed on the color monitor and evaluated. For evaluation the color coded wall thickness range shall be set in steps in such way that the area of interest is fully covered.

9.2

Data Evaluation The signal shall be evaluated by scrolling through the scans. All the indication of wall thickness changes shall be reported. The extent of the indication shall be reported in X- and Y- position, start, length and remaining wall thickness in a table form.

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L3-AST-NDE-102

Rev No.

Page 6 of 7

ASTRON ULTRASONIC C-SCAN CORROSION MAPPING min. remaining wall thickness [mm] t

0.95t

undisturbed

W(0.95*t

undisturbed

)

undisturbed

W true Major corrosion defect dimensions: for depth, width (W) and length (L). (L same as W) 9.3

10.0

Data Interpretation All the possible information about location of weld and other features influence to the examination shall be retrieved from the customer. Location of indication shall be compared with previous scan or dig sheet information.

REPORTING The examination report shall contain as a minimum following information:  Name and qualification of ultrasonic inspector/operator  Operating company and applicable asset owner/client  Pipeline to be examined and the examination location or dig-up position  Diameter and nominal wall thickness  Position of girth welds in the dig-up location  The co-ordinate/ reference system as applied and used in the report  Date of examination  Ultrasonic procedure and deviations from the procedure  Ultrasonic probe type and equipment identification  Scanning grid  Results of the examination  Reference to calibration file  Anomalies as noticed during the examination  External coating correction as applied including, when relevant, the coating thickness measurements  Surface condition  Scanning grid  Applicable figures/sketches/photographs, if any

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