PAUT,TOFD,AUT in lieu of Radiography.pdf

PAUT,TOFD,AUT In Lieu of RT

Pars Leading Inspection Co. Presented By: Behrouz Piranfar

9/10/2013

Techniques

Time Of Flight Diffraction (TOFD)

Contents

     

How it works Typical TOFD Display Defect Analysis Defect Example Application Advantage

Principle of TOFD

Transmitter

Receiver Lateral wave Upper tip Lower tip

Back-wall reflection  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.

How it works

DEFECT

PROBE

Reflection

Back

How it works

DEFECT

PROBE

Diffraction

How it works

Rx

Tx

DEFECT

Diffraction

How it works

Practically

Rx

Tx

How it works

Rx

Tx

Lateral wave + Pos

Amplitud dB

Tiemper ms

- Neg

How it works

Rx

Tx

Signal Diffracted

+ Pos

Amplitud dB

Tiemper ms

- Neg

How it works

Rx

Tx

Reflection From Back wall

+ Pos

Amplitud dB

Tiemper ms

- Neg

How it works

Data Collection 6 5 4 3 2 1 Rx

Tx

How it works

Phase Reversal + Pos

Amplitude dB

- Neg

Time = µ seconds or Millimetres

How it works

Greyscale Image Presentation

Depth

Lenght

Typical TOFD Display

Defect Analysis with Cursors

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

Example – Near–Surface Breaking Defect

Lateral wave blocked Sizing by measuring crack tip

Example – Mid-wall 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 – Lack of Root Penetration

 Sometimes see break in back wall signal  Defect can be sized using time-of-arrival  Similar to other root defects

Example – Lack of Sidewall Fusion

 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 - Porosity

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

Example – Transverse Cracks

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

Example – Internal Lack of Fusion

•

Strong signal but height measurement difficult

Applications  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 480˚C

 Service induced defects & structural damage  Corrosion/erosion profiling - especially weld root erosion  Thick wall components > 300mm  Clad/lining interface bond/cracking

TOFD Advantages 

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.

Challenges



Dead zone of ~3mm at outer surface



Additional B-scans necessary for transverse positioning



Hard to interpret



Difficult to apply to thin materials (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

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

 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: Shifts/day: 2

12

 Record per shift: 107 welds (32” main line and 4” piggy back)

Codes and standards

 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

RT compare with AUT

RT compare with AUT

Reporting

Thanks for your time!

Please do not hesitate to ask for further information

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:

[email protected]

Internet:

www.parsinspection.com