Enhanced Inspection Capability for Specific Applications ... · TWI has been contracted by the Pipeline Research Council International (PRCI) to perform R&D in welding, fatigue failure

Copyright © TWI Ltd 2015

Fredrik Hagglund Channa Nageswaran Lu Zhao John Rudlin

Enhanced Inspection Capability for Specific Applications using phased array ultrasonics

Malaysia NDT Conference November 2015

Malaysia International NDT Conference & Exhibition 2015 (MINDTCE-15), Nov 22-24 - www.ndt.net/app.MINDTCE-15


Plastic Pipe Weld Inspection

Weld Overlay cladding

Fatigue Crack monitoring

Aluminothermic rail weld inspection

Content


>50% of gas distribution pipes in the US are made out of plastic

Failures can occur Improper welding

procedure

Poor workmanship

Contamination

Need for an NDT system

NDT of Plastic Pipe Joints

Plastics are increasingly being used in nuclear and utility sectors



Flaws in PE pipe joints Joint misalignment

Axial/angular

Poor pipe preparation Uneven planing Poor/no scraping

Discrete planar flaws Fingerprints Oil/grease Rain droplets

Particulates Airborne dust Dirt/sand

Pipe under-penetration Cold fusions



Phased Array Ultrasonic Testing of plastic PE joints

TWI’s PolyTest system

Full volumetric inspection

EF and BF joints

Thicknesses 8-65mm

OD 90-1000mm

Manufacturing or in-service

Locating/ sizing/

characterising defects

Validated through

mechanical testing



Completed inspections for different industries across the world 30 days in South East Asia (270

joints in a 4km water pipeline) 20 days in the UK (130 joints in

fabricated pipework for water transportation)

10 days in Italy (50 joints for gas pipelines)

Good correlation with sectioned samples and mechanical tests


Clad systems of interest:

Nickel Alloy 625 on X65 pipe

Stainless steel 316L on vessel steel

Inspection methods of interest:

PAUT

EMATs

(ET and DPI)

Flaw types of interest:

Fabrication – stop/start, dis-bonds, inclusions

Service - stress corrosion cracking

Weld Overlay Cladding and inspection issues


Scattering, bending attenuation and reflection from coarse grains makes UT inspection difficult

Conventional UT inspection can be successful

using conventional shear wave probes with low frequencies

Compression wave probes can also show some improvements

TRL probes also assist with reduction of scattered reflections.

However sometimes these methods fail and further enhancement is needed

Weld Overlay Cladding


Improved interpretation using commercial PA probes

Multiple PA probes to add information

Dual matrix array probes (Olympus) to improve focussing flexibility of TRL type probe

Improving techniques by modelling the grain structure and wave propagation through it

Improvements with PA


Intermediate inspection of root and the hot pass in a Duplex 2209 girth weld with a metallurgical 316 SS cladding

Analysis of the microstructure indicated that conventional shear wave inspection was theoretically possible – according to the simple model presented earlier and on the analysis of the key parameters:

grain size vs. wavelength.

A case study


Results verified by sectioning: root flaws

Through-wall sizing is possible …. in some cases


Composite PAUT tool


1mm FBH, 1mm through-wall


Area with no known flaws (1)


Signal-to-noise – how to optimise for a particular cladding system

Improve the confidence of the operator – training

Qualify statistically to establish PoD/PoR

TWI is active on three technology fronts

How to screen rapidly over large surface areas using automation during fabrication / installation

In-service application on pipelines and vessels (NII)

Model the cladding in order to help optimise the ultrasonic techniques

Influence welding in order to get the cladding suitable for inspection

Group 1 Group 2 Group 3


TWI has been contracted by the Pipeline Research Council International (PRCI) to perform R&D in welding, fatigue failure and inspection of weld overlay cladding

Two phases have been completed to date, third phase will start in summer of 2015 focused on systematic qualification of the composite PAUT tool.

For further information please contact Max Toch ([email protected])

Work on finite element modelling of wave propagation in austenitic weld structure and its validation is ongoing in a TWI Core Research Project expected to end in late 2015 with submission of a report which will be available to Members in early 2016

Work on SCC in SS weld overlay cladding is part of an ongoing TWI Core Research Project expected to end in late 2015 with submission of a report which will be available to Members in early 2016

Current Projects

mailto:[email protected]


Illustrates:

Real time imaging of a growing crack

Use of post-processed imaging methods (FMC/TFM)

Measuring the size – Engineering Critical Assessment

Instrumentation:

M2M GEKKO using real time FMC/TFM

Olympus 10MHz 32 element linear array probe

Component:

Standard notched specimen in carbon steel

Laboratory based fatigue testing machine

Fatigue Crack Monitoring


Array ultrasonic concepts required

Focusing is essential to detect crack tip

Steering for coping with changing geometry and manipulating incidence angles

Electronic skewing using 2D arrays

Information presented here make use of commercially available probes, instrumentation and software

Ongoing developments are pushing boundaries of existing systems, leading to custom development of software in particular

Designing ultrasonic techniques


The setup


Processing the data in CIVA


da/dt towards Paris’ Law


Aluminothermic Welds in the Railway Industry

The majority of field welding is carried out using aluminothermic welding. This casting method is :

widely used for in-track welding during re-rail and defect replacement

an effective, highly mobile and cost effective

In the UK :

65,000 new welds per year produced by Network Rail and up to 2% rejection rate

1.5 million welds already on the main line railways

In Europe:

300,000 to 400,000 new welds made per year

11 million welds estimated to be on track

20% of all rail failures estimated to be caused

by weld failures


Welding Defects

The most common volumetric defects for AT welding are:

These defects can cause welds to fail in months rather than years resulting in risk to safe operation and track closures for repairs

Porosity Shrinkage Lack of fusion


Inspection Technique

Phased array techniques

To steer, focus and scan beams with a single transducer assembly, 32:128 multiplex

Focal laws were developed via modelling and trials

Hardware consists of :

8 phased array probes

Cables and connector box

Computerised instrument for data acquisition and display

Clamp on device, Railect system


Deployment of Railect System


Inspection of the Ankle of the Rail Foot

3 mm notch

2 mm

SDHs

Transducer and focal laws parameters: • 16 elements • 5 MHz • Sectorial scan 55- 75 • Step 0.5 degree


Contacts

Plastic Pipe Weld Inspection [email protected]

Weld Overlay and

Fatigue Cracks-

[email protected]

Alumino-thermic welds-

[email protected]

mailto:Inspection–[email protected]

mailto:Inspection–[email protected]



Documents

Enhanced Inspection Capability for Specific Applications ... · TWI has been contracted by the Pipeline Research Council International (PRCI) to perform R&D in welding, fatigue failure