9/10/2013

PAUT,TOFD,AUT In Lieu of RT

Pars Leading Inspection Co. Presented By: Behrouz Piranfar

Techniques

Time Of Flight Diffraction

(TOFD)

How it works

Typical TOFD Display

Defect Analysis

Defect Example

Application

Advantage

Contents

Transmitter Receiver

Lateral wave

Upper tip

Lower tip

Back-wall reflection

Principle of TOFD

Time-Of-Flight Diffraction (TOFD) relies on the diffraction of

ultrasonic energies from 'corners' and 'ends' of internal structures (primarily defects) in a component being tested using a set of two probes.

Back

PROB

E

DEFE

CT

Reflection

How it works

PROB

E

DEFE

CT

Diffraction

How it works

Rx

DEFE

CT

Tx Diffraction

How it works

Tx Rx

How it works

Practically

Tiemper ms

Amplitud dB

+ Pos

- Neg

Tx Rx

Lateral wave

How it works

Tx Rx

Tiemper ms

Amplitud dB

+ Pos

- Neg

Signal Diffracted

How it works

Tiemper ms

Amplitud dB

+ Pos

- Neg

Tx Rx

Reflection From Back

wall

How it works

1

6

5

4

3

2

Tx Rx

How it works

Data Collection

Amplitude dB

+ Pos

- Neg

Time = seconds or

Millimetres

Phase Reversal

How it works

Lenght

Depth

Greyscale Image Presentation

How it works

Typical TOFD Display

Defect Analysis with Cursors

Use of cursors on top and bottom of defect to size the defect

Lateral wave blocked

Sizing by measuring crack tip

Example NearSurface Breaking Defect

No break in lateral wave or back wall

Top and bottom signals visible (if defect deep enough)

Can measure lengths using hyperbolic cursors

Example Mid-wall Defect

Sometimes see break in back wall signal

Defect can be sized using time-of-arrival

Similar to other root defects

Example Lack of Root Penetration

Should see no perturbations in lateral wave or Back wall

In this case, top signal is buried in lateral (OD) wave

Can size easier if signals are clear.

Example Lack of Sidewall Fusion

Multiple small reflectors, each with hyperbolic tails. Usually can characterize, but sizing difficult.

Example - Porosity

Transverse cracks are rare, and similar to porosity, No perturbation of lateral or back wall

Example Transverse Cracks

Strong signal but height measurement difficult

Example Internal Lack of Fusion

Critical plant items in construction and in-service

Pressure Systems Vessels, pipelines, pipe-work

Storage facilities Tanks, spheres

Tube Vessels - Boilers, Heat Exchangers, Condensers

High Temperature Inspection Up to 480C

Service induced defects & structural damage

Corrosion/erosion profiling - especially weld root erosion

Thick wall components > 300mm

Clad/lining interface bond/cracking

Applications

Excellent POD for mid-wall defects

Good detection of miss oriented defects

Can characterize surface-breaking defects

Excellent sizing for defects in transverse

Tolerable sizing for defects in linear mode

Works very well in conjunction with pulse-echo

Rapid (and relatively low cost) inspections

Permanent Record of All Parameters

Offline Interpretation and Measurement

Excellent Repeatability.

TOFD Advantages

Dead zone of ~3mm at outer surface

Additional B-scans necessary for transverse positioning

Hard to interpret

Difficult to apply to thin materials (

Techniques

Phased Array Ultrasonic Test

(PAUT)

How it works

Scan view

Sectorial scan

Electronic scan

Scan plane

Software

Indication example

Application

Advantage

Code

Equipments

Contents

A NEW ultrasound NDT technology borrowed from medical

An Array of transducers elements in which the timing of elements excitation can be individually controlled to produce certain desired effects, such as steering the beam axis or focusing the beam

Each element has its own connector, time delay circuit and A/D converter

Elements are acoustically insulated from each other

Elements are pulsed in groups with pre-calculated time delays for each element; Phasing

How it works

Transmission (Tx)

Elements pulsed at controlled time intervals

Control of beam direction and focusing

The delays are known as Tx Focal Laws

Beam Focusing

Beam Steering

How it works

Reception (Rx)

RF waveforms received by each element are delayed, then averaged

Delays used to align the signals = Rx Focal Laws

Ultrasound reflects from defect

Elements receive ultrasound at different times due to the different beam paths

Signals then aligned by electronic circuitry

How it works

Scan view

Multiple Focal Laws

Beam is swept through many angles Wide coverage of the specimen

Side Drilled Holes

Back wall

Sectorial scan

Each PRF cycle

Aperture moves through the length of the array

No raster movement required

Full volumetric coverage achieved

Electronic scanning

Physical scan movement in one axis only

Full axial weld coverage achieved

scanning

Definition of specimen and weld geometry, coverage assessment using linear scan PAUT and representation of a typical PAUT and

TOFD combination

Scan Plane

A-Scan, E-Scan, and C-Scan, END View

Software

Sectorial Scan, Top view , TOFD

Software

The flaw volumetric position is a key indicator for determining what type of defect has been detected. (Slag, porosity, IP, LOF, ext.) Knowledge of the weld bevel and weld process is extremely helpful. In a V weld, IP would occur in the bottom root area, obviously. In a X weld IP would occur in the weld center. Regardless if volumetric position is a requirement of the referencing code, knowing the volumetric position is necessary to make the repair. Where to excavate and how deep and long?

Flaw volumetric position is defined as the position of the flaw relative to the weld or component. For weld inspection it is typically expressed as negative or positive in relation to the weld centerline or weld reference, and either embedded, connected to the ID, or connected to the OD.

SWLF flaw on weld overlay

Sk90 (-) Sk270 (+)

Weld Centerline

Flaw Volumetric Position Overview

Weld overlays are the primary indicator for determining volumetric flaw position. Using the part and weld wizard almost any symmetrical or asymmetrical weld can be created and displayed on the S-scan.

The weld overlays should be considered close approximations when used to determine flaw location. The overlay is dependent on the scanner or manual probe position being maintained or entered with a high level of precision for them to be useful.

Slag Inadequate penetration OD connected crack

Flaw Volumetric Position - Overlay

Root crack

Porosity

Inclusion

Lack of root fusion

Case Study

Present day NDT methodology utilizes radiography is the main method with a double wall double image technique to check the integrity of these weld joints.

Natural weld defects were included in 3 pipes of 44.5 mm of diameter and 5 mm thickness with a single V configuration such as: (i) toe crack and lack of incomplete penetration in Pipe-1 (ii) root crack and lack of side wall fusion in Pipe-2 (iii) an individual porosity and cluster porosities were introduced in Pipe-3 The three pipe samples were subjected to radiography and the results were analyzed The samples were also inspected utilizing the COBRA Phased Array system

Case Study

The defects are

Toe crack Incomplete penetration

Incomplete penetration

Toe Crack

Case Study

These defects are

Root crack Lack of side wall fusion

LOF

Root Crack

Case Study

The defects are

isolated porosity Cluster of porosities

Cluster Porosity

Applications

Pressure vessels

Pipelines

Portable weld inspections

Raw material production: ingots, billets, bars

Aircraft: civil and defence: In-Service Inspection

Military Pre-Service Inspection & In-Service Inspection

Power Generation: nuclear & fossil fuel: In-Service Inspection

Petrochemical: pipeline construction welds

Applications can be on anything currently applying pulse-echo testing

Corrosion Mapping

Compatible with Phased array

Detection of corrosion, erosion, pitting, etc.

2 in long array probe for fast acquisition

A scans acquisition

Use of water box improves couplant efficiency

Pressure Vessels

Low cost and easy to use

Can use conventional or PA

Uses TOFD and pulse-echo

Good approach for very thick walls

Need allowance for operator error

Simplest mechanical solution

No safety hazard, no delays

Can use magnetic wheel scanner

Pipelines

AUT gives much better inspection: better detection, better resolution

MUT is significantly worse, due to unfocused beams and inappropriate angles

RT and MUT would reject many more welds

Austenitic Piping

PA instrument, two 5MHz 16 element probes using a splitter/umbilical, and a mechanical scanner.

1.5mm hole on near side of the weld

High Temperature Inspection

Inspection with specific probe and wedge can be carried out at high temperature in many situations.

Detection and sizing up to 400C

Sample calibration Block

Phased array weld inspection

Construction Welding

Sample crack and S-scan image

Corner Crack

Inspection with 40- to 70-degree refracted angle Real-time display of S-scan and A-scan

Bolts

PA Probe 15 Degree Beam Notch #1 0 Degree Beam 360 Groove Notch #2 End of Bolt

Threads Notch #1 360 Groove Mode Conversions Notch #2 End of Bolt 0 Degree Beam

15 Degree Beam

PA Sectorial Scan

Boiler

High Volume Typically large number of welds to inspect Many different configurations (diameter, thickness, etc)

One probe covers many angles Can produce compression and shear wave No radiation hazard, chemicals and films, equipment inside pipe Great resolution High speed inspection Instantaneous recording and evaluation of results Provides immediate feedback to the welders Reproducibility

Advantages

Codes

Some quick comments

ASME is the most widely used code.

Specifically accepts phased arrays (as do most codes) as a technology, but the techniques and procedures need to be developed.

Normal procedure is to demonstrate these through a Performance Demonstration, e.g. Appendix 14 or CC 2235 in the case of ASME.

Codes

Three manual code cases: CC 2451for single angle scanning, CC 2557 for manual S-scans, manual E-scans (2558)

Two code cases for encoded linear scans: linear E-scans (2599), and linear S-scans (2600).

Codes

A Standard Guide for setting up PA is available (E-2491-06)

This SG requires full angular compensated gain (ACG) and TCG over the side-drilled hole calibration range for S-scans.

Equipments

OmniScan MX 2

TD-Handy Scan Veo-Sonatest

Equipments

OmniScan MX 2 With hundreds of units being used throughout the world, the OmniScan MX is Olympus NDTs most successful portable and modular phased array and eddy current array test instrument. The OmniScan family includes the innovative phased array and eddy current array test modules, as well as the conventional eddy current and ultrasound modules, all designed to meet the most demanding NDT requirements. The OmniScan MX offers a high acquisition rate and powerful software featuresin a portable, modular instrumentto efficiently perform manual and automated inspections.

Equipments

The veos robust design, intuitive user interface and extensive online help brings the power of Phased Array to the field based technician. The powerful veo platform unlocks a new level of performance in a portable instrument. The Inspection Plan shows the operator in 2D and 3D where probes are positioned on the test part, simplifying the inspection setup and providing an inspection reference for reporting. Multiple scans from different probes may be displayed and evaluated at the same time. Multiple Sectorial scans, top, side and end view extractions plus C scans are all supported by the veo. TOFD and Phased array inspections can be carried out in tandem at full scanning speed and with up to 2GB data files large areas can be inspected more efficiently. Full resolution waveform data is stored directly to a removable USB data key for ease of back up and transfer to PC.

Veo-Sonatest

Equipments

TD-Handy scan Is a new hand-held multifunction advanced ultrasonic used system, the TD-Handy scan is most successful portable phased array and TOFD test instrument. The TD-Handy scan allow the phased array and TOFD test simultaneously, and also possible to have strip chart scan which is not available by other portable equipments, all designed to meet the most demanding NDT requirements. The TD-Handy scan offers a high acquisition rate and powerful software features in a portable to efficiently perform manual and automated inspections. Although the TD Handy-Scan is a small hand-held instrument weighing only 3.3 kilograms, it sports an impressive battery of features and capability.

TD-Handy Scan

Reporting

Techniques

Automated Ultrasonic Test

(AUT)

What is AUT?

History

Calibration Block

TOFD

Phased Array

Mapping

Zone Discrimination

Equipment

AUT Advantage

AUT In Iran

Codes and standards

Conclusion

Contents

What is AUT?

The AUT system is used for weld inspection as a combination of two or three different techniques. It provides detailed information on the position, size, and orientation of defects. Using either a conventional multi-probe, or phased array setup, the system scans a weld in a single pass. The operator is then able to view the results in a graphical presentation.

The weld thickness is divided into a number of depth zones

Inspection concept is related to the weld bevel configuration

Full weld inspection coverage is achieved by placing an ultrasonic probe set on both sides of the weld, each probe within the set examines a layer within the weld.

What is AUT?

History

Initial AUT design Mid 1960 s

History

AUT Go-NoGo presentation Mid 1970 s

AUT paperchart recorder Mid 1980 s

AUT with PC presentation begin 1980 s

History

AUT paperchart recorder Mid 1980 s

Computerized AUT Mid 1990 s

Computerized AUT end 1990 s

Weld zoned - inspect with focused waves from both sides. (Up/Down stream)

Fast, reliable weld inspection (ASME/ASTM/API compliant)

Mechanics simpler & more reliable

Conventional UT = 1 probe per zone

Phased Array = 1 probe covers all zones

Zone 1

Zone 2

Zone 3

Zone 4

Zone 5

Zone 6

Zone Discrimination

Tandem probe application

Zone 2

angle variation focussing tandem

Zone Discrimination

76

F1

F2

F3

F4

F5

F5 F4 F3 F2 F1

Zone Discrimination

Scan Plane

Calibration Block

A calibration plate, made of an original piece of the pipeline material to be inspected, is prepared with artificial defects such as flat bottom holes and or notches, which represent actual flaws.

Artificial defects are present in each depth-zone.

Calibration Block

Calibration Block

Calibration Block

Calibration Block

Calibration Block

Capabilities

For application of the AUT, it is good practice to operate strictly according to a mutually agreed inspection procedure. To judge the results, the procedure always contains clear acceptance/rejection criteria. These criteria may be based on an Engineering Critical Assessment or Good Workmanship Standards.

Using 3 main methods (TOFD, Phased Array, Mapping) together to achieve better and more accurate results.

Lateral wave

Back-wall

A-scan

Indication

TOFD

Flat bottom hole

focus

Probe angle

Phased array

Mapping

The mapping feature enables the system to visualise the presence of the geometrical welding features such as the position of the weld cap and root penetration, which minimises the possibility of the system generating false calls. Furthermore this feature enables the system to cope with most existing UT procedures and acceptance criteria, because of its capability to detect and, to a certain extent, quantify volumetric defects.

Mapping

Mapping

Advantages of mapping:

Increase of inspection

integrity

Reducing of false calls

Characterization of defects

Can be combined with pulse-echo technique

TOFD , Phased array

Phased array inspection techniques are often complimented with TOFD. TOFD is particularly beneficial for increased length and depth sizing accuracy to compliment amplitude based pulse-echo inspections.

Data displayed in Tomoview 2.9 for offline analysis. Volume merge C-scan and TOFD B-scan.

TOFD , Phased array

Phased array, ToFD, Pulse echo

Easy UT set-up and configuration

Configure for code complience

Meets requirements of EN 1712, API 1104, DNV 2000 FS101, ASTM

E1961

Automated or manual data evaluation

Built in reporting

Zone Discrimination

Data from

Down-stream channels

Threshold

breaking defects.

Recording Threshold

Shaded area shows TOF

Amplitude Data

Colours indicate Above / Below

Acceptance thresholds

Data from Up-stream Channels

Zone Discrimination

Calibration Block

LOP

LOF

Porosity

TOFD

AUT Advantages

Can be used On and Offshore

No radiation hazard, No chemicals and films

No equipment inside pipe

Hot and cold operating temperatures

>100 welds/day onshore and>150 welds/day offshore

Digital and real-time results, final report on a DVD

High speed inspection, High POD

Instantaneous recording and evaluation of results

Provides immediate feedback to the welders

AUT Advantages

AUT Equipments

PipeWizard V4 TD-Handy Scan

2004 Siri offshore pipeline by Saipem, 83 Km SP 4&5 offshore pipeline by Saipem, 190 Km 2006 Salman (EPC 3) offshore pipeline by IOEC, ~30 Km SP 8 offshore pipeline by Sadra/DOT, 100 km 2007 SP 9&10 offshore pipeline by IOEC, ~190 Km 2008 Siri-Asaluyeh offshore pipeline by IOEC, 282 Km 2009 SP 15 offshore pipeline by IOEC, ~80 Km 2010-2011-2012 SP 12 offshore pipeline by IOEC, ~440 Km Reshadat in field , ~120 Km Forozan in field , ~120 Km SP 15,16 offshore pipeline by IOEC, ~130 Km SP 15 offshore pipeline by IOEC, ~260 Km

AUT in Iran

AUT in Iran

Total installation of pipelines using AUT in lieu of RT: ~2200 Km

Range of diameters: 4 To 56

Range or Thickness: 6mm to 38mm

Working hours/shift: 12 Shifts/day: 2

Record per shift: 107 welds (32 main line and 4 piggy

back)

2013 SP 19 offshore pipeline by IOEC, ~260 Km SP 20,21 ~ In progress

In 1998, the ASTM published the E-1961-98 code (reapproved in 2003), which covers key elements of AUT of girth welds zone discrimination, rapid data interpretation, specialized calibration blocks, and configuration procedures. The E-1961 code is designed for ECA. Similarly, in 1999, the American Petroleum Institute (API) published the 20th edition of Standard 1104, which covers mechanized ultrasonic testing and radiography of girth welds.

Other codes: DNV OS-F101, BS 4515-1 2009

TOFD Acceptance codes: European norms: BS7706 and EN583_6 ASTM E-2373-04 ASME CC 2235-1

Codes and standards

RT compare with AUT

RT compare with AUT

Reporting

Thanks for your time!

Contact us for more information at:

Mailing Address: Unit 7, No 1, Allay 1, Fiyat St,

Ekbatan-Tehran

Tel/Fax: +98-21-44694583

E-mail: Info@parsinspection.com

Internet: www.parsinspection.com

Please do not hesitate to ask for further information