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Stolt Offshore

SANTOS LTD

CASINO DEVELOPMENT OFFSHORE

INSTALLATION

Contract Number: 651008

RTD Automated Ultrasonic Testing

SAC-CTN-00251

Originator : RTD Sub Contractor

Checker : Grant Milne Senior Project Engineer

Approver : Harry Johnson Project Technical Manager

0.1 Issued For IDC May.31.05

Version Reason for Issue Issue Date Prepared by Checked by Approved by Customer

Approval


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Number : UT-05530 (Ref RTD-Steeltest Proc. RTDST-TP-UT-45)

Revision : A AUTOMATIC ULTRASONIC TESTING PROCEDURE

Date : 30.05.2005

Page : 2 of 41

Rntgen Technische Dienst bvCopyright RTD Delftweg 144, 3046 NC ROTTERDAM

2003 Rntgen Technische Dienst bv

This document has been produced by Rntgen Technische Dienst bv (RTD).

Each copy is controlled and remains property of RTD.

No part of this publication may be reproduced, stored in a retrieval system, or

transmitted in any form or by any means without the prior permission of:

Rntgen Technische Dienst bv

Inquiries can be directed to;

Rntgen Technische Dienst bvDelftweg 144, P.O box 10065

3004 AB Rotterdam

The Netherlands

Phone : +31 10 2088208

Fax : +31 10 4158022

E-mail : [email protected]


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Content

1.0 Purpose

2.0 Scope

3.0 Reference Specifications

4.0 RotoscanEquipment Description

4.1 Multi-channel Ultrasonic Equipment

4.2 Recording

4.3 Scanner and Umbilical

4.4 Calibration Set-up

5.0 Rotoscan Set-Up Configuration

5.1 Inspection Set-Up Configuration

5.2 Probe Configuration5.3 Probe Frame Layout

5.4 Calibration Block

6.0 Equipment Calibration

6.1 General

6.2 Setting of Inspection Gates

6.3 Sensitivity Settings

6.4 Scanning Preparation & Surface Conditions

7.0 Acoustic Coupling Fluid

8.0 Examination

8.1 Calibration Check

8.2 Step by Step description of Rotoscan Examination

8.3 Verification circumferential position


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9.0 Interpretation of Results

9.1 General

9.2 Reportable Indications9.3 Sizing

10.0 Acceptance/Rejection Criteria

10.1 Repairs

11.0 Reporting

12.0 Personnel Qualifications

12.1 The Rotoscan Operator

12.2 The Manipulator Operator

Attachment 1 : Inspection Set-up Configuration

Attachment 2 : Transducer Selection

Attachment 3 : Calibration Manufacturing Drawings

Attachment 4 : Rotoscan Cover sheet Report

Attachment 5 : Rotoscan Site Report

Attachment 6 : Reportable indication sheet

Attachment 7 : Gain settings calibration record


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1.0 Purpose

The purpose of this procedure is to determine Weld Acceptability during the

pipeline construction of 12" Line-pipe of the "Santos Casino Pipeline Project"

as required.

2.0 Scope

This procedure details methods for Automated Ultrasonic Weld Inspection(via the RTD Rotoscan Unit) of pipeline girth welds. The Rotoscan is an

automated ultrasonic inspection system for pipeline girth welds, based upon

the Pulse Echo Method, enhanced with mapping images and Time of

Flight Diffraction.

The weld is divided into a number of depth zones which are each inspected

by one of an array of probes. The probes are arranged such that the entire

weld is examined from both sides in a single circumferential scan. The

ultrasonic information is transferred to a computer for data presentation and

analysis.

Inspection results are stored on harddisc ( incl. backup removable harddisc )

and a hardcopy of each weld is printed in a compressed black & white

image covering the pipe circumference. After completion of pipeline

inspection, all data will be stored on CDROM or DVD and presented to

client.

This procedure is valid for following welds:

Diameter : 12

Wall thickness: 18.1 and 22.2 mm

Weld bevel : J-prepMaterial : SML 450 IPD


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3.0 Reference Specifications

AS 2885.2 2002 Pipelines Gas and Liquid Petroleum Part 2 WeldingDNV-OS-F101- 2000 Submarine Pipeline Systems Offshore StandardSNT TC 1A - 1996 Society of Non destructive Testing Technical CouncilEN 473 European NormAS ISO/IEC 17025 1999 General requirements for the competence of testing and

calibration laboratoriesRTD CP 31105 Rev 4 Calibration check procedure for ultrasonic multi-channel

equipmentRTD CP 31108 Rev 1 Control Procedure of calibration blocks for Rotoscan

systemUT-05531 latest Rev Manual UT procedure for weld repairs

A-512 Rev 3 RTD Written Practise

4.0 Rotoscan Equipment Description

4.1 Multichannel ultrasonic equipment

A multichannel ultrasonic flaw detector shall be used, type Rotoscan,

which provides an adequate number of inspection channels

(referred to as sequences) to ensure a complete volumetric examination

of the weld through thickness in one circumferential scan.

Each inspection channel will provide a linear A scan presentation,

which can individually selected.

The system meets the following minimum requirements:

4.1.1 Global parameters

- Number of Sequences : 32

- Main Gain : 0 40 dB

- Digitiser Sampling Frequency : 50 MHz

- Overall System P.R.F : 4 kHz


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4.1.2 Gate Parameters

In each sequence, the following parameters shall be selectable:

- Transmitter and Receiver channel 1- 32

- Gain 0 - 40 dB ( 2dB increments )

- Gate start and length. ( min increment 0,1mm )

- Delay ( mm )

- Threshold level 5% - 100% Full Screen Height ( FSH ).

- Recordable output selection between; Amplitude and/or Transit

distance, Mapping, TOFD and Coupling.- Selection between First / Highest amplitude detection within gated

section

4.1.3 General

- Electronic noise shall be lower than acoustical noise in all

sequences, for the probes and sensitivities to be used during the

inspection.

- The signal to noise ratio of each sequence during examination

shall be at least 20 dB for shear waves probes.- The signal to noise ratio for TOFD probes, measured on the 2mm

calibration block notch in the root, shall be at least 12 dB

4.2 Recording

Inspection results are presented on-line on a 20" colour monitor.

The screen layout and number of used sequences are configured to present

the thickness of the weld to be examined. Distance delays are applied to

the output channels to compensate for variable transducer circumferential

positions. The presentation shows the following information;

- Amplitude and relevant transit distance (superimposed )

- Mapping image sections

- Go-Nogo image section

- Coupling check section

- TOFD image section

- Circumferential position information- Header section with possibility to present job specific information- Time and date of inspection

The raw data of each inspected weld will be stored on a hard disc.

In addition a back-up will be made on an removable hard disc.Inspection files can be reviewed at any time.

The inspection results will be printed in a compressed black-white image

of the weld circumference.


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4.3 Scanner and Umbilical

The scanner to be used shall meet the following requirements:

- Automated operation during examination, however manual

operation may be permitted as detailed in section 8.2 part F .

- Easy and quick mounting to the guideband.

- Capable of taking up a minimum of 10 individually spring loaded

ultrasonic probes, of which the distances to the weld centreline

can individually be set.- Coupling controllable per probe, or per set.

- 15-45 metres of cable length.

- The scanner is equipped with an encoder for accurate

measurement of the scanner position within the pipeline

circumference.

- Minimum speed of 40 mm/sec

- Maximum speed of 80 mm/sec

4.4 Calibration Set-up

The calibration Set-up consists of a pipe piece, being a part of thin wall 12" pipe.

On the support a guiding band is mounted at the same distance from the

weld centreline as the guidance band on the weld to be tested.

In the pipe piece a cut-out area is present where a calibration block with

the proper wall thickness as pipe under test, is mounted which is used

to monitor the ongoing system performance.

The calibration block(s) to be used shall be made from original piece of pipe,

without coating and no weld included.

5.0 Rotoscan Set-up Configuration

5.1 Inspection Set-up Configuration

The inspection set-up is visualised in Attachment 1.It shows the selected

probe angle(s) for the selected pulse echo, tandem and TOFD technique

within the zones to be examined within the given weldbevel

configuration.


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5.2 Probe Configuration

In Attachment 2 the selected probes with their parameters are listed which

are used for the inspection. All probes have an unique number for QA/QC

purpose relating to the manufacturing process and tests within the RTD

probe manufacturing department. The numbers of probes used are part of

the inspection parameter file within the Rotoscan inspection program.

5.3 Probe Frame Layout

The probes used for inspection are positioned within a probe frame.

5.4 Calibration block

The calibration block shall be of matching wall thickness of the item

under test and contain artificial defects to install the inspection

sensitivity. The block shall be designed with sufficient surface area to

enable the transducer array to scan the target areas in one single pass.

Reflectors for the pulse echo technique shall be flat-bottom holes and

notches, which are positioned at the weldbevel.

TOFD notches are used to identify the system capability to detect surface

breaking indications. The calibration block shall be manufactured and

tested according to procedure CP-31108. The calibration block shall be

identified with a hard stamped unique serial number.

Attachment 3 shows the calibration manufacturing drawings.

Notes:

* Through-holes 2mm in both ends of calibration block at centre line.These reflectors are to locate weld centre position only.

* Notches, are to indicate the weldbevel position.

* TOFD notches are used to identify surface breaking indications.

6.0 Equipment Calibration

6.1 General

The ultrasonic equipment shall be electronically calibrated at least once per

3- month period according calibration procedure to CP-31105 latest revision.


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6.2 Setting of Inspection Gates

- Pulse echo and Tandem channels

With each transducer positioned for the peak signal response from the

calibration reflector the detection gates are to be set. The gate shall start

2-8 mm ( allowance for width of heat affected zone ) before the

theoretical weld bevel preparation. The gate ends shall be after the

theoretical weld centreline. All gates will be programmed to record

amplitude and/or transit distance information. The gate length of thetransit distance in the root channel will be extended to enable root

penetration registration and for the amplitude sequence the gate shall

end at the position of the root TOFD notch.

- Mapping channels

The mapping gates in the body of the weld starts 2-8 mm

(allowance for width of heat affected zone) before the theoretical weld

bevel preparation. The gate length will be extended to enable cap

reinforcement registration. The mapping gates in the root will be set

identical to the pulse echo transit distance channels to enable the

registration of the root penetration.

- TOFD channel

The TOFD gate start will be set 3 mm before the arrival of the lateral

wave and should extend up to and including the first back-wall echo, to

achieve full cover of wall thickness.

Note: The gate settings may be altered if geometry indications dictate.If gate settings are changed the client should be informed.

6.3 Sensitivity Settings

With each transducer positioned for the peak signal response from the

calibration reflector ( flat bottom holes ) the detection gates are to be set. In this

position the probe holder is fixed to the probe frame. The equipment sensitivity

( echo amplitude ) for all inspection channels shall be set at 80% Full Screen

Height.

Calibration of surface breaking zones to be done using the 1 mm notches, for

the embedded zones a 3mm FBH.


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Mapping channels in the body of the weld will be used to detect the presents of

porosity , and in addition to identify the position of the weld cap reinforcement

for pattern recognition purpose. The sensitivity setting is on a 1.5mm FBH at

80% FSH + 6 dB but should not be so great as to cause interfering electrical or

geometric noise that could be misinterpreted.

Mapping channels in the root will be used to identify the position of the root

penetration for pattern recognition purpose. The sensitivity as a minimum is

equal to the related pulse echo channels, increased with additional 8dB to

ensure proper detection but should not be so great as to cause interferingelectrical or geometric noise that could be misinterpreted.

The lateral wave (RF signal) of the TOFD channel sensitivity is set at 40% FSH.

The probe distance for TOFD should be calculated at 2/3 of the wall thickness

(nominal beam angle) 10mm.

6.4 Scanning Preparation & Surface Condition

The scanning area shall be free of weld spatters and other irregularities which

may interfere with the inspection.

Adjacent to one weld side, prior to welding, over the complete circumference

at a fixed distance from the nose of the weld preparation, a scribeline shall be

available for guidance band position adjustment. The distance from this scribe-

line to the weld centre-line should be 40mm with an accuracy of 1mm.

Transition welds shall be machined, to match the thinnest wall thickness over a

width of at least 150mm.


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7.0 Acoustic Coupling Fluid

- Tap water shall be used as acoustic coupling fluid, to be able to test

welds in the range up to 95C.

- The coupling is supplied between probe contact surface and the

pipe via supply channels incorporated in the probe housing.

- To enable good acoustical contact between the ultrasonic probes

and the pipe surface, conditions as mentioned under 6.4 apply.

8.0 Examination

8.1 Calibration check

During the first 10 welds a calibration scan shall be made for every inspected

weld. Thereafter the frequency of calibration is reduced to a minimum of one

calibration every five welds. The calibration scan shall be performed every

weld during slow-lay of the pipeline. Slow-lay is defined as one weld every

two hours

The Gain settings calibration record (attachment 7) shall be filled out twiceper shift after being done for the first 10 welds.

A re-calibration shall be carried out if;

* The calibration of an inspection function differs more than - 3 or + 2 dB

from the previous calibration.

* The gate settings need to be adjusted when they deviate more than +/-

0.25 mm with the previous calibration.

* After a weld repair. The print-out of the calibration run shall become part

of the repair.

After equipment breakdown If there is any reason to assume that a mechanical impact or other event

occur.

In case the calibration differs from the initial setting, outside the given

tolerances, the applicable probe(s) and coupling shall be checked. If the

calibration has to be changed, the welds before this calibration up to the previous

calibration will be re-evaluated taking the differences in the gain and/or gate

adjustment into account.

The result of each calibration scan shall be printed, tabulated and stored onharddisc.


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8.2 Step by Step Description of a Rotoscan Examination

Before starting the step by step description the UT-system is already calibrated

and a calibration scan with a record has been made.

a. Adjust guiding band on the pipe to a distance of 110mm from the marks(scribe-line, which is 40mm from the weld centre-line) and parallel to

the weld. The accuracy of the band setting should be 1mm.

b. Scanner Operator will mark zero-point on the 12 o clock position ofthe pipe.

c. Switch on coupling supply .

d. Locate the scanner over the top of the pipe and make sure that all

probes are past the zero point and are in proper contact with the pipe

surface.

e. Attach the scanner to the band.

As long as cooling water is vaporising ( surface temperature >100)

scanner shall not be attached to the band..

f. Switch on system and automatically the weld will be scanned in

clockwise direction. In the event of a drive motor failure, the probe

frame may be manually driven provided that the weld scan

integrity is not compromised. This may be proven by an acceptable

comparison of the last automated calibration scan to the first

manual calibration scan. This is envisaged to be temporary

measure and best efforts will be made to repair and re-install the

automatic drive system.

g. Systems and coupling supply will switch off automatically after a full

scan with an overlap of minimum 5 cm.

h. Check the inspection results on defect indications and proper coupling.

Use the transit distance recording and mapping and images for

validation of defect indications within the root area and proper

alignment of the guiding band. In case of lack of coupling a second scan

will be necessary.

i. Remove the scanner from the band and attach it to the calibration block.


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8.3 Verification circumferential position

The accuracy of the circumference, measured by the system, should be checked

by comparison of indications (defects or geometrical) in the overlap of the

system. The tolerance is 10mm. This check should be done at least once

every five welds

9.0 Interpretation of results

9.1 General

With the transit distance measurements and with the information from the

Mapping and TOFD channels visible on the result presentation, indications

shall be judged whether they are from the weld geometry or defects.

The coupling channels shall be checked for couplant loss. Action shall be taken

if one of the following events occur.

Couplant loss length is greater than the smallest allowable defect in theacceptance criteria.

In case an indication is present in the TOFD channel in a position of

couplant loss a re-scan shall be required. If couplant loss persists in thezone of the indication in the TOFD, the indication shall be validated by

manual UT.

In case an indication is present in the PE channel experiencing loss ofcouplant directly adjacent to the length where couplant was lost, a rescan

shall be required.

9.2 Reportable indications

The inspection result should be evaluated and/or reported as follows ;

To be agreed

This shall be performed off-line.

The report format is given in attachment 6

This is intended to give a measure of the overall weld quality and allow

feedback to the welding foreman.


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9.3 Sizing

9.3.1 Length Sizing

The beginning and end of the defect shall be determined from the points

where the signal falls below 40%FSH either side of the indication

If a resolvable TOFD indication is seen without an associated pulse echo

amplitude >40%FSH, then the defect length shall be determined for the

resolvable part of the image. This is the only instance where length shall be

measured by TOFD.

For the length measurement of porosity mapping channel shall be used. The

length of the porosity is defined as the start of the cluster to the end of the

cluster in circumferential direction.

9.3.2 Height Sizing

The height of an indication shall be measured by PE (pulse/Echo). Sizing

curves shall be used where 80%FSH = 2,5mm defect height for the

embedded zones and 80% FSH= 1.2mm for the surface breaking zones.

If the indication can be resolved by TOFD (clear separation between upper

and lower diffraction tip) the measured defect height by TOFD shall

apply.

The methodology is summarised in the AUT Defect Height Evaluation Flow

Chart (see page 17).


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9.3.3 Sizing of porosity

When white points (> 40%FSH) are present in the mapping channels.

Porosity shall be evaluated using the mapping channel(s).

The height of the porosity is defined as distance between start and end of

the porosity along the sound axis divided by the cos (), where is the

probe angle.

For the height of the porosity see following table:

Measured cluster size

along the sound beam

(mapping)

in mm

Reportable

height

in mm

2 1.5

3 2.3

4 3.1

5 3.8

6 4.6

7 5.4

8 6.19 6.9

10 7.7

11 8.4

12 9.2

13 10


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9.3.4 AUT DEFECT HEIGHT EVALUATION FLOW CHART


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11.0 Reporting

At commencement of the project we shall issue a covering UT Report

( see attachment 4) with all parameters of the system that shall not change

throughout the project. Then on a daily basis throughout the project, a

Rotoscan site report will be issued for reporting of daily test results with

the following information;

- Project and RTD project number

- Weld No;- Date;- Diameter;- Wall thickness;- Number of indications, location on circumference, length and

location in depth;

- Acceptable ( C-comply) or rejected (DNC- does not comply).

For a sample of the Rotoscan site report, see attachment 5

The following set-up for a filename will be used during pipelay.

Example of filename for weld 1234.

1234 Scan of mainline or double joint weld

1234C Calibration scan performed before scanning weld 1234

1234R1 Scan of weld 1234 after repair

1234R1C Calibration scan performed before scanning weld 1234R1

12.0 Personnel qualifications

All NDE personnel must be able to speak the English language.

12.1 The Rotoscan operator

The ultrasonic lead operator performing the examination shall:

- Be qualified in accordance to RTD written-practice A-512 which

conforms to SNT-TC-1A 1996 and EN-473 (level II).

- Has experience with multichannel UT-equipment;

- Be trained and passed the RTD in-house testing for MechanisedUltrasonic Inspection.

12.2 The Manipulator operator

The manipulator operator, handling of scanner mechanism shall:

- Be trained in using mechanised UT-manipulator to satisfaction of

Rotoscan operator


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Attachment 1 Inspection Set-up Configuration


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Attachment 2: Transducer Selection

Example; Will be updated after arrival cal blocks

Calibration Block 18.1 and 22.2mm (J-prep)

Zone Reflectors

Cal. block

Frequency

probe

Angle Inspec.tech. Crystal Ident.

Z1

Notch 15x1x2

Notch 15x2x1

4 MHz

6 MHz

55

65

Pulse Echo

TOFD

10 x 13 mm

6 mm

E

G

Z2 FBH 3 mm 4 MHzTx 40

Rx 46Tandem

Tx 10 mm

Rx 12 x 14 mmA

Z3 FBH 3 mm 4 MhzTx 40

Rx 46Tandem

Tx 10 mm

Rx 12 x 16 mmB

Z4 FBH 3 mm 4 MHzTx 40

Rx 46Tandem

Tx 11 mm

Rx 12 mmC

Z5 FBH 2 mm 4 MHz 50 Pulse Echo 13 x 16 mm D

Z6Notch 15x1x2

Notch 15x2x1

4 MHz

6 Mhz

60

65

Pulse Echo

TOFD

10 x 15 mm

6 mm

F

H


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Attachment 3 Calibration manufacturing drawings


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Attachment 5 Rotoscan report


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Attachment 6 Reportable indication sheet


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Attachment 7 Gain settings calibration record

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