Introduction to NDE automation1.pdf

Introduction to the development
of NDE techniques for utilities
and refineries in Taiwan
Yung-How Wu
2009.05.08

Outlines
 Development of remote operated inspection
technique for ABWR RIP pipe welds
 Study of Ultrasonic Techniques on the Inspection
of NPP Components
 Development of Automated Electromagnetic
Techniques for Inspecting Inner Cracks of LPG
Tanks
 Reliability Assessment of Automated Eddy
Current System for Turbine Blades
 Inspection of HTHA on Reactors in CPC Refinery

Development of remote operated
inspection technique for ABWR RIP
pipe welds

Background
 The Taipower ABWR under construction was developed
by working group of GE, Nippon Tokyo Electric, Hitachi
and Toshiba. And, the vessel was constructed by Bobcock
and Hitachi K.K..
 One of major differences between ABWR and
conventional BWR is the five pairs of RIP（Reactor
Internal Pump）designed for independent cooling water
circulation. Each RIP was connected to the RPV by a
circumferential weld located in narrow gap as shown in
Fig. 1.
 Automated NDE method and scanner is required for the
inspection of RIP circumferential weld located in the
narrow gap in future ISI.

Objectives
 To develop a special scanner to carry UT, camera
or even ET probes to inspect the RIP
circumferential weld located in the narrow gap.
 To order special PA probes for narrow gap
inspection.
 To develop remote controlled inspection method
and procedures for performance demonstration in
Taiwan or EPRI before ISI.

RIP and Inspection Location
ABWR
RPV
RIP
18mm gap
RIP weld

System configuration for RIP inspection

Ultrasonic PA system to use
 Wesdyne IntraPhase 32/128
 4 probes may be used at one time

Mock up for PD
 To simulate RIP
 Reference sample installed
 To practice scanner
assembling and dissembling
 To develop remote
controlled inspection method
and practice for PD training

Study of Ultrasonic Techniques on
the Inspection of NPP Components

Objective
Using low frequency TRLPA probes to
evaluate the inspection of various nuclear
power plant components in PWR or
ABWR in Taiwan and, to determine the
detectability and testing parameters of this
TRLPA technique for dissimilar metal
welds or coarse grain materials used.

Inspection difficulties for
DMW, CSS & RIP
 Cast or forged stainless steel and nickel alloy
materials are commonly used for piping
components or jointed by Dissimilar Metal Welds
as reactor coolant system (RCS) pipings. And,
inspection difficulties arose mainly due to:
 Ultrasonic reflection from interface.
 Ultrasonic scattering of coarse grains which
reduced S/N ratio.
 Ultrasonic distortion due to velocity change in
anisotropic microstructures.

Typical construction of DMW
 Nozzle：Carbon Steel with Cladding.
 Buttering：Nickel Alloy.
 Weld：Nickel Alloy.
 Piping：Stainless Steel.

Cracks & Notches
on either sides of weld

No. 25
Macrostructure of CSS Samples
 No. 8 & No. 11：Columnar and Coarse grained structure, the max.
grain size is around 17 mm in outer region of the sample.
 No. 25：Equiaxed Grain, Average Grain Size is around 0.2 mm in
all region.
No. 8 No. 11

PA System
& TRLPA probes
 Zetec OmniScan MX
 Pulse Width：30 ~ 500 ns
 Bandwidth: 0.52~19 MHz
 Imasonic TRLPA
 Array：2D (2-3×11)
 Frequency: 1.5 MHz

PAUT Results of DMW sample
 Axial flaw A2 located in
buttering, inspected with
TRLPA probe by using
28~43 LW law.
 Circumferential flaw C1
located in pipe side. Two
components of the clustered
flaws can be clearly
distinguished.

PAUT Results of DMW sample
Flaw
No.
Type Location L
(mm)
H
(mm)
Detection (SNR) L-
6dB
(mm)
H
meas.
(mm)
ESL
(mm)
ESH
(mm)
From Pipe
(dB)
From Nozzle
(dB)
NP1 Cir.
Notch
Pipe 53.8 5.8 24 NA 60.1 6.6 6.3 0.8
NN1 Cir.
Notch
Nozzle 54.1 5.8 NA 14 62.0 4.4 7.9 -1.45
C1 Crack Pipe 50.8 7.9 13 9 62.1 8.0 11.3 0.1
C3 Crack Buttering 45.7 6.3 12 10 48.0 6.7 2.3 0.4
C5 Crack Nozzle 40.6 13.4 11 17 48.1 14.7 7.5 1.3
A2 Crack Buttering 30.5 11.9 14 18 30.0 10.8 -0.5 -1.1
 All cracks were detected from both sides.
 The through-wall sizing error was less than 1.5mm in all cases.

Inspection Results (CSS No. 25)
Cir Notch
Depth: 7.6 mm
SNR：32 dB
Axial Notch
Depth: 7.6 mm
SNR：35 dB
SNR: 40 dB
SNR: 37 dB
SNR: 36 dB
 SDH  4.7 mm

Inspection Results – CSS No. 11
No. 11 - Notch
Cir Notch：Length 28.4 mm, Depth 6.4 mm.
TPC 2D probe (1.5 MHz)

Inspection Results of RIP sample
PA probe：Imasonic 1.5M16×2E32-7.
Circumferential Inner Notch：LD = 50.8mm0.7mm.
Linear Scan, Refraction angle：45.
Inner Notch

Inspection Results of RIP sample
PA probe：Imasonic 1.5M16×2E32-7.
Circumferential Inner Notch：LD = 50.8mm0.7mm.
Linear Scan, Refraction angle：25.
Inner Notch

Conclusions
 The low frequency L-wave generated by 1.0 MHz dual 2D matrix array
probes allow for reliable detection of all cracks through the dissimilar
metal weld and the buttering.
 The 1.5 MHz 2D TRLPA probes are also able to detect all reflectors in
cast stainless steel and RIP samples in our cases.
 The corner trap signals of surface-breaking flaws were found more
obvious with lower refraction angle beam around 20.
 Using Imasonic 1.5M16×2E32-7 PA probe, the notches in SS weld were
detected with high S/N ratio at low incident angles around 25. The
result suggested lower angle rather 45 is more suitable for the surface
breaking crack inspection in some cases.

Development of Automated
Electromagnetic Techniques for
Inspecting Inner Cracks of LPG Tanks

Objective
To integrate an automated
ElectroMagnetic Array based system for
inspecting inner surface cracks on LPG
Tanks.

Background
 LPG tanks were frequently subjected to SCC on
inner surface during service and must be
inspected from inside regularly.
 Conventional ISI by MT or PT is toilsome and
costly.
 Extremely hot working condition inside in summer
 Scaffolding & epoxy coating removal for inspection
 EMA/ACFM has been used to detect surface
breaking cracks without removing coating on
components.

Electromagnetic Array
Techniques
V2/V1 = (2d + △) / △
∴ d =△/2((V2/V1) – 1)
V1
Span = △
V2
d
Surface
current Surface crack
Current
perturbation
Surface current
Crack tip
ACPD EMA or ACFM

Benefits of
EMA/ACFM techniques
 Capable of measuring both crack depth and length.
 Inspecting cracks without removal of surface
coating up to several millimeters and hence
reducing cost and time.
 Inspection results may be kept as digital records
for better review and monitor.
 Various signal displays are helpful in defect
discrimination.

Samples with Artificial Cracks
Notches Cracks
Block
Defect(mm)
Type
Depth
Lengt
h
Positn
Weld-6 Toe Crack ~2mm 12 30
Weld-9
Centerline
Crack
~2mm 13 38
41210
150
Plate-1
A group
B group
C group
Defect(mm)
Type/Positn Depth Length Width
Notch/A群
2 40 0.25
2 20 0.25
2 10 0.25

Characteristic Defect Signals
 A single defect may be detected by three successive EMA channels.
 Defect could be clearly identified by various displays.
Abs Abs
Corr
Imp

Probe scanning & Defect
detection
 Automatic scanner was used to move the probe with
different orientations.
 Transparencies were stacked between probe and sample to
create different lift-off .
Sample plate
with cracks
Probe
Auto scanner
Transparencies
Scanning
direction
Notch
axial
Crack
axial
Scanning
direction

Signals in Various Conditions
實驗1_Plate1_Plate2
0
1
2
3
4
5
6
0 1 2 3 4 5 6 7
實際深度(mm)
量測深度(mm)
 Weakest response at 380
 Amplitude decreased exponentially
with Lift-Off
 Measuring error could be
controlled down to ±25%
0
2
4
6
8
0 20 38 50 90
角度 o
振幅
1張
5張
15張
10mmx1mm 裂縫
0
5
10
0 10 20 30
投影片張數
振幅(Max/Min)
數列1

Automated Inspection System
 EMA System
 Lizard solo
 64 channels SDDPU
 Scanner Control Console
 PC + TFT monitor
 Motor control module
 Motion control &
monitoring package
 CCD camera and 2-axis
stage
 Scanner
 With 4 magnetic rollers
 Carrying 32-channel
probe
Control Console
EMA System
CCD Camera
Direct Cable Connection
NTSC Standard
Motor Control
Position Sense
EMA Signal

Automated Inspection Method
 Weld and Plate regions were
Inspected individually
 Weld: along the weldment
 Plate: as shown
 Scanner was moved to the top
position and then scan
automatically on each path.
 Scanning route was
monitored by CCD camera
and full coverage was assured.
CCD Camera
NTSC Standard
Position Sense
Frame GrabberCard
LPG Tank Steel Plate
Field of View
Real Scan Path
Ideal Trajectory

Field Trials
 Scanning is controlled and
monitored through CCD camera
by inspector operating below the
LPG tank.

Conclusions
Laboratory and preliminary field trials proved
the method satisfactory in detecting real
cracks down to 10mm in length and 1mm in
depth in both regions. However, minor
improvement on the scanner manipulation is
required before practical application.

Reliability Assessment of
Automated Eddy Current System for
Turbine Blades

Objective
 to develop an automated eddy current
method assisted by a self-aligned
manipulator scanning along the disk rim of
Westinghouse turbine. The light-weighted
manipulator was mainly designed for
inspecting blade on L-2 stage disk where
root cracks were most frequently found
during ISI.

Background
 Blades and disk rim of turbine were
frequently subjected to fatigue cracking and
resulted in unscheduled shutdown and even
more a total failure of turbines. Hence,
reliable routine inspection is crucial to
operation safety and efficiency of turbines
operation.

Westinghouse turbine blade &
scanner designed for inspection
Airfoil-trail Edge
Airfoil-lead Edge

Definition of defect size vs signal
amplitude

Conclusions
The signal response analysis was used to establish
the practical reliability analysis method for this
automated eddy current inspection system. The
probability of detection curve was shown as a unit
step function which indicated the quality of the
system was good enough. When defect length was
greater than 0.5mm the POD was almost 100%,
However, the result was obtained from a mock up
in a well-controlled experimental environment
then further test should be carried out in the field.

Inspection of HTHA on Reactors
in CPC Refinery

Reactors and surface condition

HTHA problem and inspection method

TOFD results to identify and
measure HYHA crack

Introduction to NDE automation1.pdf

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