Examination Procedures For Ultrasonic Thickness Measurement

EXAMINATION
PROCEDURE FOR
ULTRASONIC
© This is a property of Sabsolaz Nigeria Ltd and as thus should not be reproduced without due permission.
STANDARD OPERATING DOCUMENT No.: SAB/SOP/UT/01
PROCEDURES FOR ULTRASONIC
WALL THICKNESS Revision: 001
DOC. OWNER SABSOLAZ NIGERIA LTD. Effective Date: 08 January, 2019
Page # Page 2 of 13 Effective Due Date: NIL
PREPARED BY: QA/QC MANAGER Last Review Date: 15th March, 2021
Prepared By Reviewed by Approved by

QA/QC MANAGER OPERATIONS MANAGER GENERAL MANAGER
Inah James David Okafor Victor Aziegbemhin
Date: Date: Date:

th th
th
04 March, 2021 5 March, 2021 15 March, 2021
READ BY
NAME TITLE SIGNATURE DATE
Solomon Aziegbemhin MD 08th March 2021
CONTENTS
#Number Content Title Page Number

1. INTORDUCTION 4 of 14
2. SCOPE 4 of 14
3. DEFINITIONS 4 of 14
4. SAFETY 4 of 14
5. PERSONNEL QUALIFICATION 4 of 14
6. IDENTIFICATION AND DATUM POINT 5 of 14
7. SURFACE PREPARATIO 5 of 14
8. EXTENT OF INSPECTION 6 of 14
9. EQUIPMENT SPECIFICATION 6 of 14
10. EQUIPMENT CALIBRATION 6 of 14
11. FUNCTION TEST 7 of 14
12. TECHNICAL DETAIL 7 of 14
13. REPORTING 7 of 14
14. ACCEPTANCE CRITERIA 8 of 14
15. DISCARD CRITERIA 8 of 14
16. APPENDIXES 9 of 14
AMENDMENT/UPDATE SHEET
DATE SECTION EFFECTED ISSUE STATUS REVISION BY
1.0 INTRODUCTION
1.1 The objectives of this document are to provide the customer, certifying authority
and NDT personnel with a documented and audible procedure for the execution /
certification of ultrasonic wall thickness testing and provide NDT personnel with a
general but specific procedure which addresses the activities associated with the
inspection but steel pipe work /plating.
1.2 Prior to ultrasonic wall thickness evaluation SABSOLAZ NIGERIA LTD. shall
inform NDT personnel of the scope of work ahead. All NDT personnel shall ensure
that they are familiar with the scope of work and this procedure and that all relevant
information is documented or otherwise made available to facilitate the completion
of evaluation and reports.
2.0 SCOPE
2.1 The scope of this procedure covers the use of ultrasonic wall thickness
measurement techniques using DM2 pulse echo type equipment when thickness
gauging carbon steel plate or piping.
3.0 DEFINITIOINS/REFERENCES
3.1 All terms used within this procedure shall be defined in BS EN 330-4:2000:
Glossary terms, latest edition Non-standard terms and abbreviations used
within this procedure are as follows:
 SNT – Society of Non-Destructive Testing
 PCN – Personnel Certification in NDT
4.0 SAFETY
4.1 All personnel performing wall thickness measurements shall be cognizant with
company safety procedures where applicable.
4.2 When deemed appropriate, and as instructed by SABSOLAZ NIGERIA LTD.
within company safety procedures, all technicians performing ultrasonic testing
shall wear prior to and during inspection, safety glasses, safety boots, safety
coveralls and gloves as a minimum.
5.0 PERSONNEL QUALIFICATION
5.1 When deem appropriate by SABSOLAZ NIGERIA LTD. all operators performing
thickness checking when using digital thickness measurement equipment shall be
trained, and experienced by a competent person, or to a recognized standard, in
accordance with client requirements.
5.2 For further investigations of any area found susceptible to Corrosion with a level II
practitioner in SNT /PCN or equivalent may be used to lest components within the.
Categories to which they are qualified for and must hold a current valid certificate.
5.3 When deemed necessary to SABSOLAZ NIGERIA LTD or its clients the operator
shall demonstrate to the satisfaction of those concerned that they are able to comply
with the requirements of this procedure.
6.0 IDENTIFICATION AND DATUM POINT
6.1 The operators to ensure repeatability of the readings shall document where
appropriate a process of traceability
6.2 A datum point shall be clearly marked by means acceptable by the client in order to
identify the start point. As a minimum piping, 4 areas should be tested in a
clockwise direction 12, 3, 6 and 9 o’clock positions, on horizontal pipe, the top
shall be the 12 o’clock position, on vertical pipes the forward-facing side shall be
the 12 o’clock position. Refer to appendix B for recommendations when gauging
tubulars.
6.3 Areas of non-specified wall thickness readings shall be reported to SABSOLAZ
NIGERIA LTD or its client as deemed appropriate.
6.4 Any repairs carried out as a consequence of unacceptable wall thickness readings
and are subjected for re-gauging shall he identify separately from the original work
or as agreed by SABSOLAZ NIGERIA LTD or its client.
7.0 SURFACE PREPARATION
7.1 All area(s) under gauging shall be free from all contaminants such as debris, rust,
scale, or any foreign matter that may hinder or affect the accuracy of results.
7.2 All materials examined shall have a surface temperature of not greater than 50 oC.
7.3 Mechanical cleaning operations must be carefully managed as not damage the
surface of gauging leading mechanical damage.
7.4 In some cases, the paint I protective coating may prevent the transmitter of the
ultrasonic beam. The paint coating, however, shall not be removed unless otherwise
approved by SABSOLAZ NIGERIA LTD Management or her clients.
8.0 EXTENT OF INSPECTION
8.1 All areas to be gauged shall be uniquely identified on a request sheet or similar
form approved by SABSOLAZ NIGERIA LTD or her client.
8.2 Where sections or part sections that require gauging, details and or drawings clearly
stating the areas and extend of the gauging, shall be supplied, unless otherwise
agreed by contracting parties.
9.0 EQUIPMENT SPECIFICATION
9.1 Typically, equipment used shall be a digital thickness meter type DM2 or
equivalent. The gauge shall be hand held type with a digital read out capability and
shall undergo calibration in accordance with the manufacturer’s specification and
readings shall be accurate to within +0.1mm.
9.2 Equipment I probes shall be capable of measuring accurately to within 0.5 mm wall
thickness.
9.3 The nominal frequency of the probe shall be 5MHz, and 100mm in diameter.
9.4 The calibration block (step wedge) shall be of similar material to that under test
ranging from 2.00 mm through to 20.00 mm @ 2mm steps
Probes TR twin crystal 10mm Dia 5MHz

Lead Twin RG 174/u Coaxial
Calibration block Built in type – 5mm wall thickness Step
wedge -2 – 20mm wall thickness
9.5 Couplant shall be obtained by using either a mixture of cellulose paste and
water oil, or grease, and shall be of Non corrosive nature to the material
under test. The same couplant shall be used for calibration as for the
material under test.
10.0 EQUIPMENT CAIBRATION
10.1 Only equipment that holds current valid calibration cerrification to national or
international standards shall be used. Information of calibration shall he identified
on the equipment either, stickers, or any other method approved.
10.2 Records of calibration shall be kept / controlled within the company Quality
System.
11.0 FUNCTION TEST
11.1 The operator shall carry out a functional test before commencing work. The test
shall he designed to ensure the proper functioning of the equipment and its
continuing efficiency.
11.2 An updated record of all the checks shall be kept on tile within the Quality System
to include checks, and any other function test that may be required
12.0 TECHNIQUE DETAL
12.1 The area of gauging shall be free from debris, loose scale or flaking paint
12.2 A visual inspection of the area shall be carried out arid any evidence of corrosion
surface pitting or mechanical damage of any detrimental shall be reported.
(a) Place the probe onto the coupled step wedge surface on the
thickness rang closest to that specified by SABSOLAZ NIGERIA
LTD. / her client.
(b) In order to calibrate, whilst the probe remains on the coupled
surface rotate the dial on the unit to adjust the digital readout
measurement in order to match the step wedge thickness
(c) Thereafter apply couplant to a series of wedge thickness steps and
verify accuracy and tolerances of calibrated readings.
(d) Record reading displayed.

(e) Clean area and apply a protective clothing in accordance with
SABSOLAZ NIGERIA LTD. / client requirements i.e. paint,
grease, tape etc.
(f) Refer to appendix A
Interpretations
12.3 All readings taken shall be assessed in accordance with specified acceptance levels
within the referencing standards, applicable
12.4 ‘A’ scan ultrasonic equipment to better evaluate shall, further evaluate all materials
found exhibiting areas of non-specified wall thickness, / classify flaw.
13.0 ACCEPTANCE/REJECTION STANDARDS
13.1 Acceptance/Rejection Standards shall be in accordance with the

SABSOLAZ NIGERIA LTD. standards or clients requirements.
14.0 REPORTING
14.1 On completion of Ultrasonic thickness gauging a detailed report will be completed

and include essential data as follows:
 Client/Contract Title
 Job Number
 Identification (Component)
 Item number
 Material Type –Surface Condition
 Dimensions
 Procedure number
 Date of thickness gauging
 Inspectors Signature and Qualifications
 Equipment Used
 Calibration date
 Results/thickness gauging
Example
10.00
Step
10mm Wedge
5 Thickness Meter
Example
Place probe onto surface ensure couplant efficient

are record reading displayed
9.68
Pipe wall
Should there be evidence of corrosion / erosion; restrictions can be encountered as the

return signal may be reflected in another direction. In the case of this occurring an A-scan
type inspection would be required.
T
R
Restrictions
Reflected/ refracted probe
sound
Further investigation
corrosion / erosion
Work piece
APPENDIX B
Ultrasonic thickness test to be taken generally in a clockwise direction on 4 test areas as a

minimum unless otherwise agreed by SABSOLAZ NIGERIA LTD. / client.
Forward 9 12
9 o’clock 12 o’clock
3
3 o’clock
6 o’clock Horizontal piping
6’olock
Vertical piping
APPENDIX C
This standard flow chart illustrates the steps taken to conduct ultrasonic wall thickness
checks.
PRE-CLEAN
VISUAL INSPECTION
CALIBRATE EQUIPMENT
APPLY COUPLANT
PLACE PROBE ONTO

COUPLED SURFACE
RECORD RESUTS FROM

DIGITAL UNIT
POST CLEAN & PRESERVE

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EXAMINATION

Prepared By Reviewed by Approved by

Date: Date: Date:

#Number Content Title Page Number

5.0 PERSONNEL QUALIFICATION

6.0 IDENTIFICATION AND DATUM POINT

7.0 SURFACE PREPARATION

8.0 EXTENT OF INSPECTION

Probes TR twin crystal 10mm Dia 5MHz

10.0 EQUIPMENT CAIBRATION

11.0 FUNCTION TEST

12.0 TECHNIQUE DETAL

(d) Record reading displayed.

13.0 ACCEPTANCE/REJECTION STANDARDS

13.1 Acceptance/Rejection Standards shall be in accordance with the

14.1 On completion of Ultrasonic thickness gauging a detailed report will be completed

Place probe onto surface ensure couplant efficient

Should there be evidence of corrosion / erosion; restrictions can be encountered as the

Ultrasonic thickness test to be taken generally in a clockwise direction on 4 test areas as a

PLACE PROBE ONTO

RECORD RESUTS FROM

POST CLEAN & PRESERVE

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