High temperature flexible ultrasonic transducers for NDT of pipes

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High temperature flexible ultrasonic transducers for NDT of pipes

Kobayashi, M.; Shih, J.-L.; Wu, K.-T.; Jen, C.-K.; Bussiere, J. F.

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High Temperature Flexible Ultrasonic Transducers for NDT of Pipes M. Kobayashi1, J.-L. Shih2, K.-T. Wu2, C.-K. Jen1 and J.F. Bussiere1 1. Industrial Materials Institute, National Research Council Canada, 75 Blvd de Mortagne,

Boucherville, Quebec J4B 6Y4, Canada

2. Department of Electrical and Computer Engineering, McGill University, 3480 University St., Montreal, Quebec H3A 2A7, Canada

Abstract

NDT of power, chemical and petroleum plants is an increasingly important element for safety improvement and extension of plant life span. Such plants contain numerous tubular structures and to obtain ultrasonic signals with sufficient signal-to-noise ratio (SNR), ultrasonic transducers (UTs) often need to conform to these structures and operate at elevated temperatures. Flexible UTs are suitable under such conditions and adaptable to different tube diameters because they ensure good self-alignment with the object’s surface and a uniform couplant thickness. This results in good transmission of ultrasonic energy into the component and reduced noise.

In this study flexible UTs, consisting of piezoelectric films with thicknesses larger than 40 µm deposited on a 75 µm thick metal membrane, were developed for NDT applications up to 500°C. The piezoelectric films were made by a sol-gel spray technique and can be used for NDT of pipes of diameters larger than 25.4 mm. At room temperature the ultrasonic performances of flexible UTs were at least as good as commercially available 5 MHz and 10 MHz broadband UTs. At elevated temperatures accurate pipe thickness measurements were achieved because of the high SNR of the ultrasonic echoes obtained in the pulse-echo mode. For continuous NDT, an induction brazing technique which can be performed on-NDT-site was developed to braze flexible UTs to steel pipes. The brazing material serves as a high temperature ultrasonic couplant. Finally, the development of high temperature flexible UT arrays for NDT will be discussed.

M. Kobayashi, J.-L. Shih, K.-T. Wu, C.-K. Jen and J. F. Bussiere

Industrial Materials Institute,

National Research Council of Canada

75 Blvd de Mortagne, Boucherville, Quebec J4B 6Y4, Canada

Tel: 450-641-5252; Fax: 450-641-5106

Email: jean.bussiere@imi.cnrc-nrc.gc.ca

M. Kobayashi, J.-L. Shih, K.-T. Wu, C.-K. Jen and J. F. Bussiere

Industrial Materials Institute,

National Research Council of Canada

75 Blvd de Mortagne, Boucherville, Quebec J4B 6Y4, Canada

Tel: 450-641-5252; Fax: 450-641-5106

Email: jean.bussiere@imi.cnrc-nrc.gc.ca

High Temperature Integrated and

Flexible Ultrasonic Transducers for NDT of Pipes

High Temperature Integrated and

Outline

• Introduction: targeted NDT and structural health monitoring

applications

• Fabrication and performance of Integrated (

IUT

s) and flexible

ultrasonic transducers (

FUT

s)

• NDT and SHM Applications

• Conclusions

Main Applications:

NDT and Structural Health Monitoring

Energy

Nuclear Power Plant

Gas Turbine Engine

F-18 Hornet

Boeing 787

Company Logo

Fabrication and Performance of

High Temperature Integrated Ultrasonic Transducers

Fabrication and Performance of

Paint-On Ultrasonic Transducer

Fabrication Processes

(6 Steps)

Piezoelectric

Powder

_Sol-Gel

Solution

1. Powder & Sol Preparation

5. Corona Poling

2. Ball Milling

4. Thermal Treatment

6. Top Electrode Fabrication

To High Voltage

DC Power Supply

Sample

Being Heated

Needle

3. Spray Coating

Sample with

Curved Surface

Paper Mask

Air Brush

Sol-Gel

Heat Gun

Heat Gun

_{Heat Gun}

_{Line Width:}

0.5 mm

Gap Width:

Portable Fabrication Kit for On-Site Paint-On

Integrated Ultrasonic Transducers (

IUT

s)

Inside: Lower level

0.8m

0

.5

m

Inside: Upper level

0.8m

0

.5

m

0.3m

Height

Items:

1.Piezoelectric powders + sol-gel solution

2.Ball milling device

3.Air spray brush + compressor

4.Heat gun + torch

5.Poling device

6.Silver and platinum paste

High Ultrasonic Performance of

IUT

0 dB gain is used out of available 100 dB

receiver gain for this

IUT

at room temperature.

L

n

_{: nth round trip echo}

through the thickness

L

1

L

2

L

3

L

4

12.7 mm thick steel

IUT

IUT1

IUT2

IUT3

IUT4

IUT5

IUT1: (0.31 mm

φ

) 57.8dB

IUT2: (0.65 mm

φ

) 38.5dB

IUT3: (0.85 mm

φ

) 28.2dB

IUT4: (1.21 mm

φ

) 20.6dB

IUT5: (5.50 mm

φ

) 0 dB

Gain used to produce

same strength of L

1

Comparison between

PZT-c Film

IUT

and Commercial UT

L

1

L

2

L

3

L

4

Commercial

Broad band UT

Panametrics

10 MHz (4.5 dB Gain)

This IUT has at least the same performance as the broad band commercial UTs

Steel Plate

12.7 mm thick

No Couplant

Couplant

5 10 15 20

Amplitude (arb. unit)

Time Delay (µs)

L

1

L

2

L

3

L

4 5 10 15 20

Amplitude (arb. unit)

Time Delay (µs)

Panametrics

5 MHz (2 dB Gain)

L

1

L

2

L

3

L

4 5 10 15 20 Amplit ude ( a rb. unit) Time Delay (µs)

IUT (0 dB gain)

All A-Scans taken with

an EPOCH LT unit

PZT/PZT IUT

IUT

L

n

_{: nth round trip echo}

5 dB gain is used out of available 100 dB receiver gain for this

IUT

at 150°C

Thermal cycle:

heating from 22

°C to 150°C about 10-15 minutes

remaining at 150

°C for 30 minutes

cooling in air for 10 to 30 minutes

L

n

_{: nth round trip echo through the thickness}

L

1

L

2

L

3

L

4

12.7 mm

thick steel

PZT-c Film

IUT

(up to 200°C)

5 10 15

Amplitude (arb. unit)

Time Delay (µs)

L

1

L

2

L

3

L

4

156

°C

Thermal cycle:

heating from 22

°C to 400°C about 20 minutes

remaining at 400

°C for 30 minutes

cooling in air for 20 to 45 minutes

L

n

_{: nth round trip echo through the thickness}

L

1

L

2

L

3

L

4

12.7 mm

thick steel

BIT-c Film

IUT

Up to 500°C

L

1

L

2

L

3

L

4

400

°C

Errosion Monitoring at Elbow Section of

A Cooling Pipe of A Nuclear Power Plant

Structure Thickness Monitoring

Using

IUT

IUTs

2 3 4 5 6 7

Amp

litu

de

(a

rb

. u

n

it)

Time Delay (

μ

s)

0 5 10 15

Amplitude (arb. unit)

Frequency (MHz)

L

1

300°C

L

2

L

1

LiNbO

₃

-c Film

IUT

Thermal cycle:

heating from 22

°C to 800°C about 20 minutes

cooling at air for 20 to 45 minutes

26.3mm long titanium rod

L

1

L

2

L

3

L

4

L

1

L

2

800

°C

At room temperature

There has been no deterioration after 20 cycles.

0 200 400 600 800 0 10 20 30 40 50

S/N (dB)

Temperature (°C)

0 200 400 600 800 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0

Signal Variation (dB)

Temperature (°C)

LiNbO

₃

-c Film on Titanium

PZT-c Film on Steel

BIT-c Film on Steel

PZT-c Film on Steel

BIT-c Film on Steel

LiNbO

₃

-c Film on Titanium

Performance Summary of

0

1

2

3

4

Ampli

tude (

a

rb. uni

t)

Time Delay (

μ

s)

L

1

∆t

ice

L

_ice

0

Amp

1

2

3

4

litud

e

(a

rb

. un

it)

Time Delay (

μ

s)

L

1

L

_ice

∆t

ice

Ice Thickness:

0.32mm

Ice Thickness:

0.57mm

Ice was made on top of a 3 mm Al plate

h

_ice

= v

_ice

(known) x

∆t

_ice

/2

IUT

Tested at -100°C

500

o

_C

_IUT

at the Top of a Long Rod

for Thermal Cycle Test

500

o

_{C thermal cycle test of piezoelectric BIT-c film on steel substrate,}

top electrode, wire, conducting paste, connector and cable connection .

500

o

_C

Connector

500

o

_C

Conducting

Paste Bond

500

o

_{C Thermal Cycle Test}

500

o

_C

Wire

500

o

_C

Cable

150 mm Long

25.4 mm

φ

Delay Line

500

o

_C

IUT

500

o

_{C Thermal Cycle Test of one}

IUT

and Electrical Connections

500

o

_{C thermal cycle test of probe, connector, wire connection .}

Room temperature to 500

°C

Thermal Cycle Test

Ultrasonic Velocity Profile

Ultrasonic signal at 500

°C

Ultrasonic signal at 500

°C

Zoomed Signal

Zoomed Signal

After a distance of 300 mm

After a distance of 600 mm

Total: 6 dB weaker at 500

°C

Than that at 25

°C

Portable on-site Fabrication Kit

500o_{C Conducting Bond}

500o_{C BIT-c IUTs}

Platinum Paste

Top Electrode 500oC Conducting Wire

On-site Fabrication of 500

o

_C

_IUT

_s

18

4 6 8 10

Amplitude (arb. unit)

Time Delay (µs)

L

2

L

1

IUT

IUT: 58µm thick

Through a bandpass filter

HPF: 1MHz; LPF: 10MHz

Avg: 100 times

L

3

150°C

IUT

Company Logo

Fabrication and Performance

Of Flexible Ultrasonic Transducers (FUTs)

Fabrication and Performance

Laboratory Ultrasonic Transducer

Development Facility

4-Axis Robot

a. High precision and quality

b. High reproducibility

c. Sensor array and large area fabrication

d. Reduction of labor and cost

Comparison between

150°C

FUT

and Commercial UT

at Room Temperature

L

1

L

2

L

3

L

4

L

n

_{: nth round trip echo}

through the thickness

Panametrics

10 MHz (2 dB Gain)

Commercial

Broad band UT

Al Plate

15.1 mm thick

Couplant

Couplant

L

1

L

2

L

3

L

4

Panametrics

5 MHz (4 dB Gain)

L

1

L

2

L

3

L

4

0 dB gain

is used

FUT

Connection to Top Electrode

Top

Electrode

Connection to Bottom Electrode

FUT

5 10 15 20 A m pl it ude ( a rb . unit s ) Time delay (µs) 5 10 15 20

Ampitude (arb. unit

) Time delay (µs) 5 10 15 20 Amplitu de (arb. u nit) Time delay (µs)

FUT

For NDT of Pipe

Room

Temperature

Flexible Ultrasonic Transducer

(FUT)

0 dB gain

is used

out of available 100 dB receiver gain

L

n

_{: nth round trip echo}

through the thickness

L

1

L

2

L

3

L

4

OD: 70mm

Wall Thickness: 7mm

ID: 56mm

FUT

Conformed well

to the curvature

High signal strength and SNR

75μm thick

SS foil

90μm thick

Each element: 4 mm x 4 mm

Each element: 3 mm x 3 mm

50 mm

FUT

Array

For NDT of Flat and Curved Surfaces

a

b

c

d

500

o

_C

_FUT

_{Using 350}

o

_{C Bond}

L

n

_{: nth round trip echo}

through the thickness

12.7 mm thick steel

303

°C

5 10 15

Amplitude (arb. unit)

Time Delay (µs)

L

1

L

2

L

3

L

4

500°C

FUT

Bonded

To Steel Plate

150

o

_C

_FUT

_{Using 50 µm thick}

Polyimide Membranes

28 mm 102 mm Steel Pipe 28 mm 102 mm Steel Pipe

FUT on Polyimide

Gluing Tape

1 0 2 0 3 0

A

m

p

li

tu

d

e (

a

rb

.

u

n

it)

T im e D e la y (

μ

s )

L

₂

_L

4

L

6

At 150

°C

L

1

L

2

L

3

PZT-c Film on 50µm Polyimide Membrane

Flexible 5 by 6 UT-Array With

50µm Thick Polyimide Film

1 2 3 4 5 6

Amplitude (ar

b

. unit)

Time delay (µs)

At 150°C

Glued PZT/PZT

FUT

Pulser/

Receiver

Monitor

Spring loaded

Contacts

Steel pipe

Thermocouple

Hot plate

L

4

L

6

L

8

L

10

_L

12

L

2

Steel pipe: OD: 26.6 mm, ID: 21.6 mm

Tube wall thickness: 2.5 mm

Glued

FUT

Brazed

FUT

For Permanent NDT or SHM at 150

o

_C

Brazed PZT/PZT FUT Pipe Arm heater Spring contacts L2 L4 L6 Ln_{: nth round} trip echo through the thickness Ln_{: nth round} trip echo through the thickness Brazed PZT-c FUT Pipe Arm heater Spring contacts L2 L4 L6 n L :nth round trip echo through the

thickness _L2 L4 L6 L8 _L10 2 4 6 8

Am

pl

it

ude (

a

rb

. uni

t)

Time delay (µs)

L2 L4 L6 L8 _L10 2 4 6 8

Am

pl

it

ude (

a

rb

. uni

t)

Time delay (µs)

Ultrasonic Echoes with

High SNR at 150°C

Steel pipe: OD: 26.6 mm, ID: 21.6 mm

Tube wall thickness: 2.5 mm

0

1

2

3

4

5

6

7

8

+45 dB

Amplitude [V

]

Time [

μ

s]

23 C

100 C

200 C

300 C

400 C

450 C

490 C

+37 dB

Brazed

FUT

For Permanent NDT or SHM at 500

o

_C

Steel pipe: OD: 25.4 mm, ID: 19.4 mm

Tube wall thickness: 3 mm

0 2 4 6 8 10

Amplitude (arb. unit)

Frequency (MHz)

F

₀

= 1.9MHz

6dB width= 3MHz

L

1

4 6 8 10

Amplitude (arb. unit)

Time Delay (µs)

L

1

L

2

L

3

FUT

Ø8.5mm silver

top electrode on

60µm PZT-c film

3.34 mm

82.75 mm

150°C

FUT

On Graphite/Epoxy Composite

Company Logo

Thickness Measurement and

Defect Detection

Thickness Measurement and

Defect Detection

NDT Performance of

BIT-c

IUT

at 440

o

_C

Ultrasonic monitoring of the

extent of an artificial

vertical

defect

at 440

o

_C

6 7 8 9

Amplitude (V)

Time Delay (

μ

s)

0 mm

1 mm

2 mm

3 mm

Defect

Bottom

Crack growth monitoring at high temperature

d =

BIT-c IUT

150°C

Shear-Horizontal

Acoustic Waves with PZT IUT

for Long Range Defect Detection

Two line defects

can be clearly detected

Defects can be >0.22m away

2 mm thick Al Plate

IUT

25 mm

51mm

406 mm

146mm

223mm

D1, D2: Depth: 0.95mm; Width: 1mm

D1

D2

End of plate can still be detected

(0.4 m away)

S

_H,D1

S

_H,D2

S

_H,1

50 100 150 200 250

Amplitude (arb. unit)

Time Delay (µs)

S

_H,D1

S

_H,D2

S

_H,1

61.7°

PZT-c

IUT

61.7°

Thickness Measurement

Precision Estimate at 400°C

)

(

Δ

t

−

Δ

t

)

σ

’

Parameters

BIT composite film @

400°C

ƒ

₀

5.5 MHz

T

0.55 µs

B

4.6/5.5

ρ

0.96

SNR

₁

37.5 dB

SNR

₂

34.2 dB

3.7 ns

Digitization

Resolution (100MHz)

2 ns (with cross correlation

and interpolation)

V

_L

5583 m/s

Thickness

Measurement

Accuracy

16µm

L

1

L

2

L

3

L

4

12.7 mm

thick steel

Conclusions

a.

Fabrication and ultrasonic performance of miniature IUTs and FUTs have

been presented. IUTs and FUTs may be coated, glued, bonded or brazed

onto structures with curved surfaces on site.

b.

At room temperature IUTs and FUTs may have at least the same ultrasonic

performance as those offered by commercial broadband UT. High signal to

noise ratio and operation frequency centered between 1 and 30 MHz can be

obtained.

c.

Operation temperatures of IUTs and FUTs may range from -100

°C to 800°C.

d.

Longitudinal, shear, surface and plate acoustic waves can be generated and

Company Logo

Thank You!