Ut Thickness

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HELLIER
HELLIER
WELCOME TO THE
UT THICKNESS
COURSE
• 24 Hour Course.
• Class Hours: 8:00am to 4:30pm.
• Breaks: At the discretion of the instructor.
• Lunch: 1 hour - 11:30 - 12:30
• Restrooms:
• Safety:
HELLIER
COURSE OBJECTIVES
• Purpose: Present the body of knowledge of
Ultrasonic Thickness Testing

• Objective: Impart an understanding of the
following topics of UT Thickness Inspection

– Principals and Theory
– Equipment and Materials
– Techniques and Calibrations
– Inspection Variables
– Procedures and Specifications
HELLIER
STUDENT OBJECTIVES
• Purpose: Learn the body of knowledge
for Ultrasonic Thickness Testing

• Objectives: To achieve an
understanding of UT thickness
inspection and a proficiency in using
portable ultrasonic thickness gages for
taking thickness measurements.
HELLIER
LET’S GET ACQUAINTED.
• Name:
• Company:
• Job Title:
• Background:

HELLIER
CLASS FORMAT
• Instructor led presentation of information

• Informal open discussion

Ask pertinent questions

Be respectful of others
HELLIER
PERSONNEL CERTIFICATION
• SNT-TC-1A
• NAS 410
• CP 189
• ISO 9712
• ACCP
• CSWIP
• CGSB
• AWS-NDE
Employer Certification
Central Certification
HELLIER
NDT PERSONNEL
QUALIFICATION AND
CERTIFICATION
Recommended Practice SNT-TC-1A:

• Guidelines for NDT PQ&C to assist the
employer
• Published by ASNT
• Uniform procedures for the qualification and
certification
• Satisfy the employer's specific requirements.
HELLIER
QUALIFICATION AND
CERTIFICATION
HELLIER
NDT NAMES
• NDT – Nondestructive Testing
• NDI – Nondestructive Inspection
• NDE – Nondestructive Examination or
Evaluation

• Common Names – Zyglo test, Magnaflux
test, Sonic test, etc.
HELLIER
ELEMENTS OF A
NONDESTRUCTIVE TEST
• Source which provides a probing medium
• Changes to the probing medium
• Detect the changes
• Record or indicate the changes
• Interpret the cause of the changes
HELLIER
DEFINITIONS
• Indication - Response from an NDT Test
– False - Caused by improper technique;
usually not repeatable
– Non-relevant - Condition in the part;
intentional or unintentional
– Relevant - Unintentional discontinuity in
the part

• Discontinuity - An interruption in the
physical structure of the test piece that may
be intentional or unintentional
HELLIER
DEFINITIONS
• Flaw – An unintentional discontinuity, an
imperfection; which may, or may not be,
rejectable

• Rejectable Discontinuity - A flaw related to
a relevant indication that exceeds the
acceptance criteria; a rejectable, relevant
indication.
HELLIER
DEFINITIONS
• Defect – a discontinuity that will cause the
part not to be used for it’s original purpose.
A condition that will render the part not
useable or that could cause part failure or
malfunction
HELLIER
NDT Interpretation/Evaluation Flowchart
Indication
Accept Reject
Non-
Relevant?
Relevant
Indication
False?
Violate
Acceptance
Criteria?
Use?
No No
Ignore
No
No
Interfere
with
Inspection?
Yes
Re-Process
Yes Yes
Yes
Interpretation
Evaluation
HELLIER
MAJOR NDT METHODS

VT AE
PT NRT
MT TIR
UT AE
RT VA
ET Laser Methods
HELLIER
ADVANTAGES OF NDT
• All of these methods of NDT share some
common advantages:

– Increased product reliability
– Increased product safety
– Increased productivity
– Increased profitability
– Increased product serviceability
– Minimized product liability
HELLIER
ADVANTAGES OF NDT
• However, they also share a common
limitation:
The NDT method applied, regardless of
the equipment and materials used, will
only be as effective as the inspector skill
allows. It is not a panacea!
HELLIER
ULTRASONIC INSPECTION
Inspection method using sound
• Introduces high frequency sound
waves into test object.
• Measures two quantities:
• time for sound to travel.
• amplitude of received signal.
HELLIER
HISTORY
• 1880 Curie brothers discovered piezoelectric
principle.
• Certain crystals develop a voltage when
pressure is applied.
• 1881 Lippman discovered the piezoelectric
principle operates in reverse.
• Piezoelectric crystals will change shape
when a voltage is applied.
HELLIER
HISTORY (CONTINUED)
• 1929 Sokolov performed thru-transmission.
•Continuous wave travels through material
under test.
•Displays transmitted and received signals.
HELLIER
HISTORY (CONTINUED)
• 1941 Floyd Firestone (US) and James
Sproule (England) developed pulse - echo
test instruments.
• Echoes reflected from material boundaries
and discontinuities provide test signals.
HELLIER
UT THICKNESS APPLICATIONS
Discontinuity detection.

Thickness measurements.
• Corrosion/Erosion.
• Pipe Wall Thickness.
• Vessel Wall Thickness.
• Plastics
• Precision Measurements
HELLIER
UT - ADVANTAGES
• Deep penetration into material.
• Portable equipment: battery powered.
• Pulse echo requires one sided accessibility only.
• Accurate for thickness measurement and
discontinuity location.
• Permits volumetric examination.
• Suitable for go/no-go testing: audible & visible
alarms.
• No known hazards
HELLIER
UT - LIMITATIONS
• Test object must be able to conduct sound.
• Fine grained, elastic material.
• Liquid couplant is required.
• Requires a trained operator.
• Discontinuities just below surface may not be
detected.
• Dead Zone
HELLIER

WHAT IS SOUND
Mechanical energy
propagating through a
material in the form
of pressure waves.
HELLIER
UT instrument produces an electrical pulse
Transducer:
• Converts electrical pulse to sound energy.
which travels through the material
• Returning echoes are converted back into
an electrical signal

UT instrument processes the returning
signals for display
GENERATION OF SOUND
HELLIER
ULTRASONIC TESTING
Ultrasonic Transducer
• Like a speaker when transmitting;
• Like a microphone when receiving

Piezoelectric Effect:
- Apply electrical energy, mechanical
energy is produced
- Apply mechanical energy, electrical
energy is produced
HELLIER
PIEZOELECTRIC EFFECT
When exposed to an alternating current an
element expands and contracts
- + + - - +
HELLIER
WAVE MOTION
The pressure in the sound waves displace
the molecules in the material.
• Various wave modes can be generated.
Longitudinal, Shear, and Surface
• Wave modes are defined by their particle
motion relative to direction of sound wave
travel.
HELLIER
VELOCITY OF SOUND
The speed that sound goes through a medium.

Depends on two material properties:
• Density: How tightly packed are the
molecules.
• Elasticity: Restoring force of the electrical
bonds.
And the Type of the Sound Wave
HELLIER
VELOCITY
Measured in distance travelled per unit of
time.

– Inches/second (in/sec)
– Inches/microsecond (in/µsec)
– Kilometers/second (km/sec)
– meters/second (m/sec)
– centimeters/microsecond (cm/µsec)
Velocity is affected by temperature
HELLIER
LONGITUDINAL WAVES
• Also known as Compressional Waves
• Particle Vibrations parallel to the direction
of wave propagation.
Propagation
Particle vibrations
HELLIER
LONGITUDINAL WAVES
• Alternating zones of compression (high
pressure) and rarefaction (low pressure)
Propagation
Particle vibration
• Travel in solids, liquids and gases.
• Highest velocity of all wave modes.
HELLIER
SHEAR WAVES
• Vibrations at right angles to the direction of
propagation.
• Finds flaws not parallel to the surface
Propagation
Particle vibration
Not used with thickness gages
HELLIER
SURFACE WAVES
• Elliptical vibrations
• Special wave at the surface of the part
• Finds cracks and scratches
Not used with thickness gages
HELLIER
SOUND WAVE MEASURMENTS
• Cycle: A complete repetition of particle
motion

• Frequency: Number of cycles of vibration
per second

• Wavelength: Distance the sound wave
travels during a cycle
HELLIER
FREQUENCY
• Frequency Ranges:
– Audible range: 20 to 20,000 Hz.
– Ultrasound: above 20,000 Hz.
– Commercial testing: 100 kHz to 25 MHz.

• Frequency units:
– Hertz (Hz): cycle per second.
– Kilohertz (KHz): thousand cycles per second.
– Megahertz (MHz): million cycles per second.
HELLIER
WAVELENGTH
• Distance sound travels during one cycle.
Measured from one point on cycle to an
identical point on the next cycle.
λ
λ
HELLIER
WAVELENGTH / FREQUENCY

f
V
= ì
V = velocity
f = frequency
λ = wavelength
V = f × λ
Frequency and wavelength are inversely
proportional
• frequency increases, wavelength decreases
• frequency decreases, wavelength increases
HELLIER
SOUND BEAM GEOMETRY
Near
Field
Far
Zone
Intensity
varies
Beam Diverges (Spreads)
Distance
Y
o

HELLIER
SOUND BEAM AREAS
• Near Field:


• Far Field:


• Yo (Near Field Length): Distance
HELLIER
THE SOUND BEAM
• The length of the near field can be
calculated from the following formula:

V
f D
N
×
×
=
4
2
V
f D
N
×
×
=
4
2
Where:
N = Near Field Length (mm) f = Frequency (MHz)
D = Crystal Diameter (mm) V = Velocity (Km/sec)
HELLIER
NEAR ZONE
• The larger the diameter the longer the
near zone
• The higher the frequency the longer the
near zone
• The lower the velocity the longer the near
zone
V
f D D
4

4
Near Zone
2 2
= =
ì
HELLIER
THE SOUND BEAM
• Beam Divergence can be calculated from
the following formula:
|
.
|

\
|
×
×
= ¸
f D
V .
arcsin
22 1
Where:
¸ = Beam Divergence Angle f = Frequency (MHz)
D = Crystal Diameter (mm) V = Velocity (Km/sec)
HELLIER
BEAM SPREAD
• The larger the diameter the less the beam spread
• The higher the frequency the less the beam spread
• The lower the velocity the less the beam spread
Df
KV
D
K
Sine or
2
ì u
=
HELLIER
ATTENUATION
• Material Loss Attenuation:
•Scattering of sound by grain structure of
the material.
•Conversion of sound energy into heat
• Sound amplitude lost due to:
•Attenuation
•Beam Spread.
HELLIER
SOUND AT AN INTERFACE
At an acoustic interface sound will be reflected
and/or transmitted across the interface
Reflected
Transmitted
Interface
Interface
Incident Wave
Interface: Boundary between two materials
HELLIER
ACOUSTIC INTERFACE
• Boundary between two materials with
different acoustic impedance values.
Reflected
Transmitted
Acoustic
Interface
• The amount reflected
and transmitted
depends upon the
acoustic impedances
of the two materials.
HELLIER
ACOUSTIC IMPEDANCE (Z)
Impedance: Opposition a material offers to the
propagation of sound travelling through the
material.

• The greater the ratio (mismatch) between the
two impedances of the materials,

• The greater the percentage of sound reflected.
Z = V x µ
V = Velocity µ = Density
HELLIER
REFLECTION PRINCIPLES
100 %
2
1 2
1 2
×
|
|
.
|


\
|
+
÷
=
Z Z
Z Z
RE
Formula for reflected energy (RE):
Z
1
= impedance of the first material the sound is in
Z
2
= impedance of the material the sound reaches

Note: Due to the Law of Conservation of Energy

Transmitted Energy = 100% - Reflected Energy
HELLIER
TRANSDUCER DESIGNS FOR
THICKNESS GAGING
• Single crystal: materials > 1/2” thick.
• Dual crystal: corroded and eroded
materials.
• Delay line: thin materials with parallel
surfaces.
HELLIER
CONTACT TRANSDUCER
DESIGN
• Crystal thickness determines frequency of
vibrations.
• Electrodes establish electrical contact
with the crystal.
• Wear plate provides protective contact
surface.
• Damping controls crystal ringing;
absorbs rear sound waves.
HELLIER
SINGLE ELEMENT
TRANSDUCER
External
Housing
Connector
Electrical
Leads
Inner
Sleeve
Backing
Active
Element
Wear
Plate
Electrodes
Electrical
Network
• Used on thicker materials; > 1/2”.
HELLIER
DUAL ELEMENT TRANSDUCER
External
Housing
Connector
Acoustic
Barrier
Transmitting
Element
Receiver
Element
Delay
Material
Angular
Sound
Path
Test Sample
Thickness gaging of corroded and eroded
materials.
HELLIER
DUAL CRYSTAL
Used to detect reflectors
approximately parallel
to test surface.

Measure: Thickness
Corrosion
Erosion
Transmitter Receiver
Sound beam is reflected and refracted into
the receiving element
HELLIER
DUAL ELEMENT TRANSDUCER
Sound reflecting off of bottom of test piece
back into the transmitting side of the
transducer.
Material is too thin for the transducer
This is referred to as DOUBLING.
HELLIER
DUAL ELEMENT TRANSDUCER
Sound reflecting off of bottom of test piece
reflects beyond the receiving side of the
transducer.
Mode Conversion occurs
Shear Wave gives the
thickness readout.
1 ½ TIMES THICKNESS
Material is too thick for the probe
HELLIER
• Introduces sound perpendicular (normal) to the
test surface.
• Improves near surface resolution.
DELAY TRANSDUCER
Electrical connectors
Damping
Crystal
Plastic delay tip
• Detection of discontinuities near test surface.
• Thickness measurement of thin materials
HELLIER
ULTRASONIC INSTRUMENT
FUNCTIONS
• The instrument contains six basic sections:
HELLIER
INSTRUMENT FUNCTIONS
• Connecting a probe and coupling it to the
test object completes the test system
HELLIER
INSTRUMENT FUNCTIONS
The Power Supply provides voltage from the
AC or batteries to drive the other instrument
circuits
HELLIER
INSTRUMENT FUNCTIONS
• The clock initiates the chain of events that
results in one complete cycle of an
ultrasonic test
HELLIER
INSTRUMENT FUNCTIONS
• The clock emits s trigger signals, repeated at
the pulse repetition frequency (PRF)
• Depending on instrument, the PRF may be:
– Set by the operator
– self-adjusting/ or both
• The proper PRF depends on the part
thickness
• When PRF is too fast, wraparound (display
of echoes from previous test cycles) occurs
HELLIER
INSTRUMENT FUNCTIONS
• The clock triggers the Timebase and Pulser
at regular, evenly spaced intervals
HELLIER
INSTRUMENT FUNCTIONS
• The timebase initiates time/distance display
on the instrument’s horizontal scale
– used for distance readout
HELLIER
INSTRUMENT FUNCTIONS
• The pulser sends initial pulse to transducer,
causing sound to enter the test object
– initial pulse goes through the
Receiver/Amplifier to the display
HELLIER
INSTRUMENT FUNCTIONS
• The Initial Pulse is a fast rising, high voltage
pulse that activates the transducer

• Duration of transducer ringing determines
the length of the dead zone

• Dead zone is the depth range in the test
material where relevant indications are
hidden inside the Initial Pulse’s indication
HELLIER
INSTRUMENT FUNCTIONS
• Sound travels through the test object as
time elapses along the display
HELLIER
INSTRUMENT FUNCTIONS
• Sound reflects from material boundaries
and discontinuities

HELLIER
INSTRUMENT FUNCTIONS
• Transducer echo voltage is processed by the
receiver and displayed
Echo height is determined by reflected sound
HELLIER
INSTRUMENT FUNCTIONS
• Time base Controls

– Zero Offset Control
• adjusts when the horizontal display
starts relative to the activation of the
initial pulse
– Range Control
• adjusts the amount of time displayed
along the horizontal scale to correspond
with sound travel time through a specific
thickness of material

HELLIER
INSTRUMENT FUNCTIONS
• Time base Controls
– Velocity Control
• adjusts the amount of time displayed
along the horizontal scale to
correspond with sound travel time
through material of a particular
velocity

HELLIER
INSTRUMENT FUNCTIONS
• Pulser Controls

– Pulser Energy Control
• adjusts the size of the Initial Pulse
– Damping Control
• adjusts transducer performance for
resolution versus penetrating power

Note: Both Pulser Energy and Damping
affect duration of the dead zone
HELLIER
INSTRUMENT FUNCTIONS
• Receiver processes and amplifies signals
going to the Display
– Processing is provided by detector and
filter sub-circuits

• Detector sub-circuit can provide choice of
various types of signal passing through the
receiver – RF or Selected video mode
HELLIER
INSTRUMENT FUNCTIONS
Comparison of RF and all Video modes
Negative half is often used to present a more
narrow echo (better resolution) for thickness
testing
HELLIER
COUPLANTS
• Liquid (usually) used to exclude air from
the path of the sound beam.
• Considerations
• Wetting Ability
• Viscosity
• Reactivity
• Ease of removal
• Expense
HELLIER
TYPICAL COUPLANTS
• Water
• Oil
• Cellulose and water mixture
• Grease/Petroleum Jelly
• Commercially prepared
•High temperature couplants
HELLIER
THICKNESS INSPECTION
Thickness inspection incorporates:
• Pulse Echo Technique
• Resonance Method

Measurements are made of:
• Thickness of new parts
• Erosion / Corrosion
HELLIER
THICKNESS CONSIDERATIONS
• Calibration procedure should be followed
• Couplant should be thin as possible
• Part surfaces should be smooth
• Part surfaces should be parallel
• Gage gives reading of first large echo
– Need to verify actual reflector at times
– A-Scan Gages provide this verification
HELLIER
THICKNESS CONSIDERATIONS
• Use two point calibration when possible
• Calibration block
– Known, documented NIST thickness
– Same material as part being inspected
– Similar temperature to the part
• High temperature increases part thickness
• Insure “new” reading for each location

HELLIER
SOUND TRAVEL GEOMETRY
• Digital Thickness gages measure distances to
reflectors which are parallel to the part’s
surface
– Straight beam transducer
– Dual Element transducer
– Delay Transducer

HELLIER
BASIC TEST TECHNIQUE
PULSE-ECHO
• Test object information provided by
reflected sound energy
• Individual echo signal for each reflector
perpendicular to beam axis
HELLIER
BASIC TEST TECHNIQUE
PULSE-ECHO
• Displayed Information: echoes reflected
from acoustic interfaces
HELLIER
BASIC TEST TECHNIQUE
RESONANCE
• Resonance tests are used for thickness
measurements
– Continuous wave of variable frequency
– Resonance occurs when material
thickness equals 1/2 of wavelength
– Has been replaced by pulse-echo method
– Still used in aerospace for thickness
readings and bond-testing
HELLIER
BASIC TEST TECHNIQUE
RESONANCE
• Displayed Information is derived from
fundamental and harmonic frequencies
HELLIER
DATA PRESENTATION
• Display hardware
– Electro-luminescent displays
– Liquid crystal displays
– Paper chart recorders
– Digital readouts
– Computer screens
HELLIER
DATA PRESENTATION
• A-scan
– horizontal scale:
displays time to
indicate distance
– vertical scale:
displays
transducer output
voltage to indicate
echo amplitude
HELLIER
DATA PRESENTATION
• Digital Readouts

• B-scan
Side view of test object:
profile of interfaces
reflecting sound beam

– Immersion Testing
– Digital Thickness Gages
– Computer Applications
HELLIER
TIME/DISTANCE
RELATIONSHIP
• Velocity is different in different materials
• Accurate calibration is crucial
• Gage converts travel time to thickness
Thickness = (Velocity) (Time)
2
HELLIER
THICKNESS GAGING
• Uses High Frequency Sound Waves
– Typically 5.0 MHz thru 20.0 MHz
– Longitudinal Sound Energy
• Thickness Measurement From One Side
• Nondestructive
HELLIER
PRECISION THICKNESS
GAGING
• Single Element Transducers
• Highly Damped, Delay Transducers
• Provides High Degree Of Accuracy
• New Materials for Quality Control
– Metals, Plastics, Glass and Composites
HELLIER
CORROSION THICKNESS
GAGING
• Uses Dual Element Transducers
• Erosion/Corrosion
• Typically on Metal
• Irregular/Pitted Reflecting Surface
HELLIER
DUAL ELEMENT
TRANSDUCER ON CORRODED
MATERIAL
• Roof angle focuses sound at the base of
pits.
TX RX
HELLIER
SINGLE ELEMENT
TRANSDUCER ON
CORRODED MATERIAL
• Much of the sound is scattered away from
the transducer.
HELLIER
DUAL ECHO AMPLITUDES
• First Echo is not
always the Largest
• Due to:
– Roof Angle
– Thickness
– Material Velocity
– Delay Material
TX RX
First
Backwall
Echo
Second
Backwall
Echo
1 st Echo
2 nd Echo
HELLIER
DUAL ELEMENT
ADVANTAGES
• Roof Angle narrows the beam for pits
• High Temp. capabilities (≈ 1,000° F)
• Separate Elements
– Use Higher Initial System Gain
– Better near surface Resolution
– Stable Readings on Rough Entry Surfaces
HELLIER
CHOOSING TRANSDUCERS
• Material
– Carbon steel
– Cast material
– Aluminum
• Thickness Range
– Min and Max thickness
• Geometry
– Min Diameter
– Convex/Concave Surface
– Surface Condition
HELLIER
TRANSDUCER CRITERIA
• Frequency
– Higher Frequency -- Better Resolution
– Higher Frequency -- Better Sensitivity
• Roof Angle
– Steeper Angle Will Have Shorter Focus
• Delay Material for High Temperature
HELLIER
THICKNESS GAGING
PERFORMANCE VARIABLES
• Penetration: Ability to pass through a
material interface.
– Improves with longer wavelength.
• Wavelength increased by decreasing
frequency.
HELLIER
THICKNESS GAGING
PERFORMANCE VARIABLES
• Resolution: Ability to individually display
reflectors located at slightly different
depths along the sound beam.
– Resolution increases with an increase
in bandwidth and/or frequency.
HELLIER
ZERO OFFSET ERROR
• Incorrect Zero Offsets
– With Worn Transducers
– On Curved Surfaces
– On Rough Surfaces
Zero
Block
Worn Probe
on Curved
Pipe
Worn Probe
on Zero
block
Rough
Surface
ZERO
OFFSET
ZERO
OFFSET
ZERO
OFFSET
ZERO
OFFSET
Caused by Built In Test Block
HELLIER
AUTO PROBE RECOGNITION
• Optimizes setup and receiver gain.
• Transducer V-Path correction.
• Accurate measurements over large
thickness ranges.
True
Thickness
Sample
Angular
Sound Path
TX RX
HELLIER
AUTO ZERO COMPENSATION
– Measures Time Through
Transducer
– Tracks Transducer Wear
– Compensate For Thermal
Drift At Elevated
Temperatures
Rx
Delay
Tx
Delay
•Uncouple and Press Zero Key to:
HELLIER
ECHO-TO-ECHO
Standard = [1 Coating]+[1 Metal] + [1 Metal] + [1 Coating]
Measurment 2
Total Thickness
Coating and Metal
Echo-to-Echo = [-1 Coating]+[1 Metal] + [1 Metal] + [1 Coating]
Measurment 2
Thickness of
Metal Only
Coating
Metal
2 METAL
2 METAL
COATING
2 METAL+2C
COATING
1st ECHO
2nd ECHO 3rd ECHO
2 METAL
COATING COATING
Sound
Entry
HELLIER
AUTOMATIC ECHO-TO-ECHO
• No Gates To Set
• Gage Automatically Finds The Two
Highest Back wall Signals
• Marker Indicates Detected Echoes
• Users Verifies Proper Detection
HELLIER
MANUAL ECHO-TO-ECHO
• User Selects Detection By Adjusting:
– Signal Amplitude
– Blanking Gate
HELLIER
TWO POINT CALIBRATION
• Try to Calibrate On Actual Samples
– Having The Same Surface Conditions
– Same Geometry
– Same Material
Cal Velocity
Enter Max Sample Thickness Enter Min Sample Thickness
Cal Zero
HELLIER
THICKNESS GAGE
ADVANTAGES
• Size and Cost
• Ease of Calibration and Operation
• Auto Probe Recognition
• V-Path Correction
• Auto Zero Compensation
• Greater Data Logging Capability
• Thru Paint Echo-to-Echo Measurements
• Better Thickness Accuracy
HELLIER
THICKNESS ACCURACY
• Thickness measurement accuracy using
A-Scan gages is dependent on:
Detection
Flanking Gate Detection
Peak Gate Detection

Screen Resolution
Number of Pixels
HELLIER
FLANKING GATE DETECTION
• Accuracy Affected By:
– Coupling Pressure
– Echo Amplitude
– Leading Edge Shape
– Transducer Alignment
– Front Surface
Condition
– Backwall Surface
Condition
– Material Properties
SIGNAL
AMPLITUDE
AT 50dB
SIGNAL
AMPLITUDE
AT -6 dB
THRESHOLD
GATE
Detection 1
Detection 2
HELLIER
PEAK DETECTION
• Dual Signals Have Multiple
Peaks
• Peaks Change Due To:
– Transducer Alignment
– Surface Condition
– Coupling Pressure
– Backwall Surface Condition
– Grain Structure
• Peak Detection Is Less Sensitive
to pits
TIME TO
PEAK
PEAK
SIGNAL
PEAK
GATE
PEAK
SIGNAL
PEAK
GATE
TIME TO
PEAK
HELLIER
ALGORITHMS AND DSP
• Leading Edge of Echo is Automatically
Detected
• Calibrated Accuracy Maintained When Gain
Is Adjusted
• System Runs At Lower Gain And Yields A
Cleaner Waveform
HELLIER
THE WAVEFORM
ADVANTAGE
• Voids, Disbonds And Flaws Can Cause
Internal Reflections
Problem Solution
Disbond Detected
Disbond Reflection
Blanked Out
Disbond
HELLIER
SURFACE NOISE
• Sound energy reflects from rough surfaces
and high impedance materials.
Rough Surface Aluminum
Problem Solution 1 Solution 2
Reading Surface
Reflections
Surface Noise
Blanked Out
Reduce Gain
HELLIER
GRAIN REFLECTION
Reading Grain
Noise
Grain Noise
Blanked Out
Reduce Gain

Problem Solution 1 Solution 2
• Large Internal Reflections
From Grain Boundaries
Can Cause False Readings
HELLIER
FEATURES FOR
HIGH TEMP APPLICATION
• Gain Adjust (Add Gain )
• Fast Update Rate (20 Reading/Sec)
• Freeze Waveform
• Probe Zero (Correct for Thermal Drift)
• Save Data
– Waveform
– Thickness
– Gain Settings
HELLIER
HIGH TEMPERATURE
COUPLING TECHNIQUES
• Use Appropriate Couplant for Temp Range
– F-2 Medium Temps Below 260
o
C (500
o
F)
– E-2 High Temp For 260 - 500
o
C (500-1000
o
F)
• Apply Couplant To Transducer Tip
• Use Firm Coupling Pressure
• Limit Contact Time To Five Seconds
• Wipe Transducer And Press Zero Key To
Compensate For Transducer Drift
HELLIER
ENSURE
TRANSDUCER LONGEVITY
• Limit Transducer Contact Time to Five Seconds
• Never Let Transducer Get To Hot To Hold
• If Transducer Gets Hot
– Cool in Air
– Dip Tip in Water
– Re-Zero
• Avoid Dragging Transducer Cable Across Pipe
HELLIER
DATALOGGER INPUT
PRE-LOAD
HELLIER
BARCODE WAND
• Plugs Into RS-232 Port
• Reads Standard 3 of 9
(39) Labels
• Internal Barcode
Software Is Standard
on All 26DL PLUS’S
0.267
ID:TML 1.00
THk: 0.286
B
A
R

C
O
D
E

W
A
N
D
*
HELLIER
BARCODE WAND
• Scan Barcode Tags
From Drawings
• Scan Barcode Tags
Located On The
Equipment
TML: 1.00
0.200
TML: 6.00
0.285
TML: 3.00
0.205
TML: 4.00
0.236
TML: 2.00
0.225
TML: 9.00
0.210
TML: 10.00
0.231
TML: 7.00
0.300
TML: 8.00
0.310
TML: 5.00
0.241
COMPANY: XYZ CORPORATION
DESCRIPTION: REBOILER #3, BLD 142N
DATE: 9/16/96 DRAWING: # 85236
REV: C
• Build Files As You Go
• Jump To Scanned Location In Pre-loaded
File
HELLIER
INTERFACE PROGRAMS
• Usually free with gage purchase
• Bi-directional communication
• Some use standard ASCII data
• Store data for future on version/import into:
– Other inspection programs
– Word processing software
– Spread sheet programs
HELLIER
INTERFACE PROGRAMS
• Print/Read Files and Waveforms
• Edit Files
• Produce Color Reports
• Create/Load Different File Formats
• Create Statistics Reports
HELLIER
INTERFACE PROGRAM
STATISTICS
Identifier
Thickness
HELLIER
COLOR CODED FILE
PRESENTATION
Easy Conversion Of Boiler And Grid Files
Up To Seven Different Ranges And Colors
Change Display Size and File Orientation
Show Colors only
HELLIER
OTHER DATA
MANAGEMENT PROGRAMS
• Credo Chartex Software UK
• Cortran Rios Software UK
• DataMate Krautkramer USA
• UltraPipe Krautkramer USA
• EMPRV EDS (under development) USA
• EPRI Check/Works EPRI USA
• IDM Exxon USA
• Meridium (under development) USA
• PIPE Sys Atomic Software UK
Name Manufacturer Country
HELLIER
Keyboard Lock
• Press
3 6
Simultaneously
Allows the operator to lock all
keys except ON/OFF and DIFF
Press again to un-lock the keyboard.
HELLIER
Change Hold/Blank
• Press and Hold
2
MEAS
Then Press
Allows the operator to
switch between the display
HOLD and the display
BLANK conditions when
no measurement is being
made (LOS).
and release both
HELLIER

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