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Portions of this manual have been taken from the General DynamicsCorporation’s Classroom Training Handbook CT 6-4, Ultrasonic Testing. AndProgrammed Instruction Handbooks PI-4-1, Introduction and PI-4-4, UltrasonicTesting. These portions are subject to General Dynamics Cooperation’s copyright1967.
Printed in the United State of America
PREPARED BY: George L. PherigoDirector of EducationAmerican Society for Nondestructive Testing. Inc.
REVIEWED AND EDITED BY THE FOLLOWING MEMBERS OF THEEDUCATIONALCOUNCILOFASNT:
Boyd W. BrownArgonne National Laboratory
Kinney C. McKeelGeneral Electric Co.
W. C. MorreyEbasco Services
PhillipA. OlkleYankeeAtomic Electric Co.
Allen ReynoldsStone & Webster Corp.
Ward d. RummelMartin Marietta Corp.
A. J. SchwarberLawrence Livermore Laboratories
Albert L. SmithWestinghouse Hanford Co.
John L. SummersRockwell Int ernational
Paul H. ToddMartin Marietta Corp.
Published by TheAmerican Society for Nondestructive Testing4153Arlington Caller # 28518 Columbus. Ohio 43228
Copyright© by The American Society for Nondestructive Testing. Inc. Allrights reserved.
-1- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
STUDENT’S GUIDE
NDT TRAINING PROGRAM
ULTRASONIC METHOD
I INTRODUCTION TO THE ULTRASONIC TRAINING PACKAGEThe training materials in this package are designed to provide a basic knowledge of the
fundamentals of ultrasonic testing. The training program that you are participating in will
contain the following classroom hours of instruction to present the information as
suggested in the ASNT publication SNT-IC-IA. Recommended Practice, June 1980
Edition.
Level 1 Training will include lectures on all 14 lesson with approximately 2.9 hours per
lesson. The student should assume the responsibility for reading all assignments,
attending lectures, and participating in class discussions. Short exams will be
administrated after each lesson to provide the student with a measure of progress and to
stimulate study.
II CONTENTS OF TRAINING PACKAGEYour training package contains the following materials with specific instructions and
assignments to be given by the course instructor.
1. STUDENT PACKAGEA. Students’ Guide which outline the purpose, content and use of the training
materials.B. 1 Classroom Training Handbook (CT-6.4) which serves as the major text for the
training course.C. 1 set of individual lecture guide packets on the fundamentals of ultrasonic
testing the lecture guide materials are provided with each lesson and are
identical to the transparencies used by the instructor during the lecture. During
the lecture, the student should use the guide to make additional notes. and the
guide will then become valuable for future study .D. 1 packet of exams. The instructor may elect to remove the exams from your
packet poor to starting the course and administer them as each lesson is
completed. An exam will be furnished for each of the 14 lesson in the training
course.
2. INSTRUCTOR PACKAGEA. The instructor’s package contains all of the information that you have with the
addition of lecture guide transparencies and exam keys.B. At the option of the instructor a set of filmstrips may be used to provide additional
depth and clanty .C. At the option of the instructor, the programmable instruction handbook may be
used for additional assignments.D. Several types of certificates are available from ASNT and may be issued at the
option of the instructor.
III OUTLINE OF LESSONSAND RELATED READINGASSIGNMENTSThe reading assignments will be made by the instructor and will correlate with the lectures
the Classroom Training Handbook (CT-6-4) and programmed instruction Handbooks (PI-
4-4) follow the lesson in this training course in the following order.
-2- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
Lesson 1 Applications, Training, and CertificationCT-6-4, Chapter 1 allSNT-TC-1A all
Lesson 2 Ultrasonic, PrinciplesCT-6-4, Chapter 2 2-5 to 2-8PI-4-4, Volume 1, Chapter 1 allPI-4-4, Volume 1, Chapter 2 2-1 to 2-6
Lesson 3 Equipment ControlsCT-6-4, Chapter 2 2-8 to 2-16PI-4-4, Volume 1, Chapter 5 allPI-4-4, Volume 2, Chapter 4 4-1 to 4- 60
Lesson 4 Wave Propagation, Reflection, and RefractionCT 6-4, Chapter 2 2-16 to 2-31PI-4-4, Volume 1, Chapter 3 all
Lesson 5 Couplants, Material Characteristics, Beam SpreadCT-6-4, Chapter 2 2-26 to 2-36PI-4-4, Volume 1, Chapter 6 allPI-4-4, Volume 2, Chapter 2 all
Lesson 6 Attenuation, Impedance, and ResonanceCT-6-4, Chapter 2 2-23 to endPI-4-4, Volume 1, Chapters 2 & 4 allPI-4-4, Volume 2, Chapter 4 4-61 to end
Lesson 7 Screen Presentations, Angle Beam Inspection WithUT CalculatorCT-6-4, Chapter 3 3-3 to 3-12PI-4-4, Volume 1, Chapter 5 allPI-4-4, Volume 2, Chapter 5 allPI-4-4, Volume 3, Chapter 3 3-60 to end
Lesson 8 Transducers, Standard Reference BlocksCT-6-4, Chapter 3 3-3 to 3-12PI-4-4, Volume 2, Chapters 1 & 3 all
Lesson 9 Immersion InspectionCT-6-4, Chapter 4 4-1 to 4-18PI-4-4, Volume 3, Chapters 4 & 5 all
Lesson 10 Contact Testing, Longitudinal & Shear Waves, Shell’s LawCT-6-4, Chapter 4 4-19 to 4-28PI-4-4, Volume 3, Chapters 1 & 2 all
Lesson 11 Applications of Angle Beam Contact TestingCT-6-4, Chapter 4, 4-19 to 4-31PI-4-4, Volume 3, Chapter 3 all
Lesson 12 Nonrelevant Ultrasonic IndicationsCT-6-4, Chapter 4 4-32 to endPI-4-4, Volume 3, Chapter 6 all
Lesson 13 Classification of Discontinuities in UTCT-6-4, Chapter 7 7-1 to 7-7PI-4-4, Chapters 1 through 7 all
Lesson 14 Identification and Compensation of DiscontinuitiesCT-6-4, Chapter 7 7-8 to end
-3- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
BASICAPPLICATIONS OF ULTRASONICS
ULTRASONICS ISAVERSATILE INSPECTION TECHNIQUE, IT IS USED TO TEST
A VARIETY OF BOTH METALLIC AND NON METALLIC PRODUCTS SUCH AS
WELDS FORGINGS, CASTINGS, SHEET, TUBING, PLASTICSAND CERAMICS.
ULTRASONICS HAS AN ADVANTAGE OF DETECTING SUBSURFACE
DISCONTINUITIES WITHACCESS TO ONLY ONE SIDE OF THE SPECIMEN.
THE OBJECTIVE OF ULTRASONIC TESTING IS TO ENSURE PRODUCT
RELIABILITY BY MEASNS OF:
1. OBTAINING INFORMATION RELATED TO DISCONTINUITIES2. DISCLOSING THE NATURE OF THE DISCONTINUITY IMPAIRING THE
USEFULNESS OF THE PART.3. SEPARATING ACCEPTABLE AND UNACCEPTABLE MATERIALS IN
ACORDANCE WITH PREDETERMINED STANDARDS
TRAININGAND CERTIFICATION
IT IS IMPORTANT THAT THE TECHNICIAN AND SUPERVISOR BE QUALIFIED IN
THE ULTRASONIC METHOD BEFORE THE TECHNIQUE IS USED AND TEST
RESULTS EVALUATED
THE AMERICAN SOCIETY FOR NON DESTRUCTIVE TESTING RECOMMENDS
THE USE OF THEIR DOCUMENT “RECOMMENDED PRACTICE NO. SNT-TC-1A.”
THIS DOCUMENT PROVIDES THE EMPLOYER WITH THE NECESSARY GUIDE
LINES TO PROPERLY QUALIFY AND CERTIFY THE NDT TECHNICIAN IN ALL
METHODS.
TO COMPLY WITH THIS DOCUMENT THE EMPLOYER MUST ESTABLISH A
“WRIT TEN PRACTICE” WHICH DESCRIBES IN DETAIL HOW THE TECHNICIAN
WILLBE TRAINED, EXAMINEDAND CERTIFIED.
THE STUDENT IS ADVISED TO STUDY THE CURRENT EDITION OF SNT-TC-1A
TO DETERMINE THE RECOMMENDED INITIAL NUMBER OF HOURS OF
CLASSROOM INSTRUCTION AND MONTHS OF EXPERIENCE NECESSARY TO
BE CERTIFIEDASAN ULTRASONIC TESTING TECHNICIAN
Lesson 1
-4- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
CERTIFICATION OF NDT PERSONNEL IS THE RESPONSIBILITY OF THE
EMPLOYERAND IS USUALLYATTHREE LEVELS
LEVELI PERFORM SPECIFIC CALIBRATIONS, SPECIFIC TESTS, AND
SPECIFIC EVALUATIONS ACCORDING TO WRITTEN
INSTRUCTIONS.
LEVELII SET UP AND CALIBRATE EQUIPMENT AND INTERPRET AND
EVALUATE RESULTS WITH RESPECT TO CODES, STANDARDS
AND SPECIFICATIONS. MUST BE ABLE TO PREPARE WRITTEN
INSTRUCTIONSAND REPORTTEST RESULTS
LEVELIII RESPONSIBLE FOR ESTABLISHING TECHNIQUES,
INTERPRETING CODES, AND DESIGNATING THE TEST METHOD
AND TECHNIQUE TO BE USED. MUST HAVE A PRACTICAL
BACKGROUND IN THE TECHNOLOGY AND BE FAMILIAR WITH
OTHER COMMONLY USED METHODS OF NDT.
THE SNT. TC. 1A DOCUMENT RECOMMENDS THAT LEVEL I AND II NDT
TECHNICIANS BE EXAMINED IN THE FOLLOWINGAREAS
A. GENERALEXAMINATIONB. SPECIFIC EXAMINATIONC. PRACTICALEXAMINATION
Lesson 1
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ASNT PROVIDES A SERVICE TO THE INDUSTRY BY PROVIDING LEVEL III
EXAMINATIONS IN THE BASIC AND METHOD AREAS, BECAUSE OF THE
INDIVIDUAL REQUIREMENTS OF THE MANY INDUSTRIES USING NDT, THE
SPECIFIC EXAMINATION IS STILL THE RESPONSIBILITY OF THE EMPLOYER.
THE FOLLOWING FLOW CHART INDICATES THE PATHS THAT CAN BE TAKEN
TO CERTIFIED ACCORDING TO THE SNT-TC-1A DOCUMENT.
ASNT CERTIFICATION WITHOUT EXAMINATION
Basic, Method, Specific15 years Education/ Experience
ASNT CERTIFICATION BY EXAMINATION
Basic, Method
LEVEL III
CERTIFICATION
PER
RECOMMENDED
PRACTICE
SNT TC-1A
June 1980 EDITION
QUALIFICATIONS
FERIFIED AND
DOCUMENTED
PER THE
EMPLOYERS
WRITTEN
PRACTICE
LEVEL III
CERTIFICATION
ISSUED BY THE
EMPLOYER
CU
ST
OM
ER
AC
CE
PTA
NC
EEXAMINATION BY THE EMPLOYER
EXAMINATION BY OUTSIDE AGENCY
EMPLOYER WAIVES EXAMINATION
Lesson 1
UT Lecture Guide
-6-
Notes :
Certificate issued to individual
This documentation as recommended
in paragraph 5, 6-3.3, 6.3.4 and
9 of the SNT-TC- 1A 1980 edition
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
UT LESSON 1QUIZ
1. The selection of one test method over another is usually the decision
of the Level I technician performing the test.2. ASNT provides a service for examining Level I, II and III personnel in
the General and specific areas.3. The responsibility of issuing a certificate to the NDT technician is
always retained by the employer in compliance with the SNT-TC-1A
document.4. If the SNT-TC-1A document is to be used as recommended guideline,
the “written Practice” must be submitted toASNT for approval.5. If the SNT-TC-1A guidelines are followed, the Level III technician
should have a knowledge of other commonly used methods of NDT
even though certification is needed only in the ultrasonic area.6. ALevel I technician performing an ultrasonic test is permitted to accept
or reject the part provided that written instructions or procedures are
given to him by a Level II or Level III. (in accordance with SNT-TC-1A)7. To comply with the guidelines of SNT-TC-1A all three levels of
technicians must take a “General”, “Practical” and “Specific” test it
examinations are used to determine certification.8. The June 1980 Edition of SNT-TC-1A permits the employer to waive
an examination for Level III personnel provided that documentation is
on file showing the technician’s qualifications.9. It is essential that every employer that uses the SNT-TC-1A document
establish a “written Practice”10. If an employer does not have a Level III in his company the services of
an outside agency may be retained to perform these functions11. An advantage of ultrasonics is that it reveals internal discontinuities
with access to only one side of the part being inspected.12. Ultrasonic inspection techniques can be used without impairing the
future usefulness of the material
Name
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
Lesson 2
ULTRASONIC PRINCIPLESIN ULTRASONIC TESTING WE USE SOMETHING CALLED “ULTRASONIC
VIBRATIONS.” WE MUST KNOW TWO FACTSABOUTAVIBRATION
1. AVIBRATION ISABACKAND FORTH MOVEMENT.2. AVIBRATION IS ENERGY IN MOTION
A DEPRESSION OF A SURFACE FROM ITS NORMAL POSITION IS CALLED A
DISPLACEMENT.
RUBER BALL
VIBRATIONS PASS THROUGHASOLID MATERIALASASUCCESSION OF PART ICLE DISPLACEMENTS. THIS CAN BE VISUALIZEDAS SHOWN BELOW:
THE STRUCTURE OF A MATERIAL IS ACTUALLY MANY SMALL PARTICLES OR
GROUPS OFATOMS.
THESE PARTICLES HAVE NORMAL OR REST POSITIONS, AND CAN BE
DISPLACED FROM THESE POSITIONS BY SOME FORCE WHEN THE FORCE IS
REMOVED, THE PARTICLES WILL TEND TO RETURN TO THEIR ORIGINAL
POSITIONS.
1 2 3 4 5
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ENERGY IS TRANSMITTED THROUGH A SOLID MATERIAL BY A SERIES OF
SMALLMATERIALDISPLACEMENTS WITHIN THE MATERIAL.
THE TRANSMISSION OF ULTRASONIC VIBRATIONS THROUGH A MATERIAL IS
RELATED TO THE ELASTIC PROPERTIES OF THE MATERIAL.
IF YOU TAP A METAL SURFACE, THE SURFACE MOVES INWARD, CAUSING A
DISPLACEMENT.
SINCE THE METAL IS ELASTIC THE SURFACE WILL TEND TO MOVE BACK TO
ITS ORIGINAL (REST) POSITION. THE SURFACE WILL ALSO MOVE THROUGH
THE ORIGINAL POSITION AND MOVE TO A MAXIMUM DISTANCE IN THE
OPPOSITE DIRECTIONTHIS COMPLETE SEQUENCE OF MOVEMENTS IS DEFINED AS A CYCLE.
THE TIME REQUIRED FOR SOMETHING TO MOVE THROUGH ONE COMPLETE
CYCLE IS CALLED THE PERIODEXAMPLE : IF THE SWINGING BALL ABOVE MOVES OVER PATH ABCDE IN
ONE SECOND, THEN THE PERIOD OF THE CYCLE IS ONE SECOND.
PLATE STRUCKWITH HAMMERTHIN PLATE
SUPPORTVIEW A
STRING
BALL
PENCIL
DIRECTION OFBALL SWING
A
B
C
D
E
DIRECTION OFSTRING TRAVEL
A
B
CD
E
CYCLE
STRING
BALL
PENCIL
Lesson 2
UT Lecture Guide
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ONE
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE NUMBER OF CYCLES IN A GIVEN PERIOD OF TIME IS CALLED THE
FREQUENCY.EXAMPLE: IF THE BALL SWINGS THROUGH THREE COMPLETE CYCLES IN
ONE SECOND, THEN THE FREQUENCY IS 3 CPS (CYCLES PER
SECOND).IF YOU STRIKE A DRUM, IT HAS A FREQUENCY THAT IS LOW,
APPROXIMATELY 50 CPS.THE TOP NOTE ON THE PIANO HAS A HIGHER FREQUENCY, APPROXIMATELY
4100 CPS.THE UNIT OF FREQUENCY USED TO DENOTE ONE CYCLE PER SECOND IS
HERTZ (ABBREVIATED Hz). ONE CYCLE PER SECOND (CPS) IS EQUAL TO
ONE HERTZ (Hz), 2 CPS = 2 Hz, ETC.SOUND TRAVELS IN METAL AS WELL AS IN AIR SOUND IS A VIBRATION AND
HASARANGE OF FREQUENCIESMAN CAN ONLY HEAR VIBRATIONS (SOUND) UPTOABOUT 20.000 Hz.HOWEVER. SOUND FROMAN ULTRASONIC TESTING UNIT ISABOUT 5,000.000
Hz. (5 MEGAHERTZ)VIBRATIONS ABOVE THE HUMAN HEARING RANGE ARE CALLED
ULTRASONIC VIBRATIONS.THE TWO TERMS. SOUND AND VIBRATIONS, AS WE WILL USE THEM WILL
MEAN THE SAME THING.THE BEST WAY TO DEFINE SOUND IS TO SAY THAT IT IS A VIBRATION THAT
TRANSMITS ENERGY BYASERIES OF SMALLMATERIALDISPLACEMENTS
JACK HAMMER
Lesson 2
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ULTRASONIC TESTING IS THE PROCESS OF APPLYING ULTRASONIC SOUND
TOASPECIMENAND DETERMINING ITS SOUNDNESS, THICKNESS, OR SOME
PHYSICALPROPERTY.
THE ENERGY IS ORIGINATED IN SOMETHING CALLED A “TRANSDUCER”WHICH CAUSES MATERIALDISPLACEMENT WITHIN THE SPECIMEN.
ATRANSDUCER IS A DEVICE THAT CONVERTS ENERGY FROM ONE FROM TO
ANOTHER.
EXAMPLE : ELECTRICAL ENERGY TO MECHANICAL, OR MECHANICAL TO
ELECTRICALA SPEAKER IN A RADIO CONVERTS ELECTRICAL ENERGY TO A
BACKAND FORTH MECHANICALMOVEMENTVIEW “A” BELOW ILLUSTRATES THE “PIEZOELECTRIC EFFECT” ELECTRICAL
ENERGY IS APPLIED THROUGH TWO WIRES CONNECTED TO A CRYSTAL,
CAUSING THE CRYSTALTO VIBRATE.THE TERMS CRYSTAL AND TRANSDUCER ARE USED INTERCHANGEABLY IN
THIS LESSON.
ELECTRICAL ENERGY CAUSES A PIEZOELECTRIC CRYSTAL TO EXPAND AND
CONTRACT, FORMING MECHANICAL VIBRATIONS. A PIEZOELECTRIC
TRANSDUCER CAN ALSO CONVERT MECHANICAL ENERGY TO ELECTRICAL
ENERGY. THEREFOR, A TRANSDUCER CAN BOTH SEND AND RECEIVE
ENERGY.
TRANSDUCER
SPECIMEN
VIEW B
NOTE:SOUND IS REFLECTEDWITHIN SPECIMEN ANDRETURN TO TRANSDUCER
WIRE
CRYSTALTRANSDUCER
VIBRATION
SOUND
WIRE
VIEW A VIEW B
ELECTRICAL ENERGY
Lesson 2
UT Lecture Guide
-11-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ENERGY TRANSMITTED BY A TRANSDUCER CAN BE EITHER PULSED OR
CONTINUOUS.PULSED ULTRASOUND IS DEFINED AS SHORT GROUPS OF TRANSMITTED
VIBRATIONS BEFORE AND AFTER WHICH THE TRANSDUCER CAN ACT AS A
RECEIVER.STEEL, WATER AND OIL WILL TRANSMIT ULTRASOUND VERY WELL, BUT AIR
PRESENTSAPROBLEM.
TRANSDUCER
OIL
STEELSPECIMEN
AIR IS A POOR TRANSMITTER OF ULTRASOUND BECAUSE THE PARTICLE
DENSITY IS SO LOW THAT IT IS DIFFICULT TO TRANSMIT SOUND ENERGY
FROM PARTICLE TO PARTICLE THAT IS WHY WE PUT OIL OR GREASE
BETWEEN THE TRANSDUCERAND THE SPECIMEN.THE PARTICLE DENSITY OF A MATERIAL HELPS DETERMINE THE VELOCITY
OF SOUND. THE VELOCITY OF SOUND WILL CHANGE AS IT MOVES FROM
ONE MEDIUM TO ANOTHER AS SHOWN BELOW. THE ELASTICITY OF THE
MATERIAL ISALSOA FACTOR.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
AIR WATER STEEL
0.33 KM/SEC 1.48 KM/SEC 5.9 KM/SEC
VISUALIZE THAT THE BALLS SHOWN ABOVE REPRESENT THE INTERNAL
STRUCTURE OFAIR, WATERAND STEEL.THE IMPULSE MOVING THROUGH THE ROW OF BALLS CAN BE COMPARED
TOAPULSE OF ULTRASONIC SOUND
Lesson 2
UT Lecture Guide
-12-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A PRACTICAL EXAMPLE OF THE VELOCITY OF SOUND IN DIFFERENT
MATERIALS IS SHOWN BELOW.
TRANSDUCER
PISTON
WATER
STEELSPECIMEN
IT WILL TAKE LONGER FOR THE SOUND TO TRAVEL THROUGH THE WATER
THAN THROUGH THE STEEL. THE SOUND VELOCITY IN STEEL IS
APPROXIMATELY FOUR TIMES GREATER THAN IN WATER.A WAVELENGTH IS CONSIDERED TO BE THE DISTANCE BETWEEN TWO
SUCCESSIVE DISPLACEMENTS.
TRANSDUCERWAVELENGTH
ABA A A
THE WAVELENGTH CAN ALSO BE DEFINED AS THE DISTANCE A WAVE
TRAVELS DURING ONE COMPLETE CYCLE.
TRANSDUCER
VELOCITY
VIEW B
1234
V
1
PISTON
SOUND WAVE
VIEW A
A B
THE SYMBOL IS USED TO REPRESENT A WAVELENGTH AND IS CALLED
“LAMBDA”
Lesson 2
UT Lecture Guide
-13-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ILLUSTRATION BELOW SHOWS A TRANSDUCER VIBRATING AT A FIXED
FREQUENCY (f)AND TRANSMITTING SOUND WAVES INTO THE SPECIMEN.
TRANSDUCERVELOCITY
SOUND WAVES
THESE SOUND WAVES MOVE AT A FIXED VELOCITY (v) THROUGH THE
SPECIMEN.THE WAVELENGTH CAN BE CHANGED IF THE FREQUENCY OF THE
TRANSDUCER VIBRATION CHANGES.
WAVELENGTHVELOCITY
FREQUENCY=
v
f
=
EXAMPLE: YOU CAN SHORTEN THE WAVELENGTH BY INCREASING THE
FREQUENCYWAVELENGTH IS A RATIO OF A FIXED VALUE (VELOCITY) DIVIDED BY A
VARIABLE (FREQUENCY).IN PRACTICAL SITUATIONS, THE SMALLEST DISCONTINUITY YOU CAN FIND
WITH ULTRASONIC TESTING IS ABOUT ½ LAMBDA(WAVELENGTH)THEREFORE . TO DETECT SMALLER DEFECTS, YOU WILL NEED
TRANSDUCERS THAT PRODUCE HIGHER FREQUENCIES.
EXAMPLE: WHAT WOULD BE THE SMALLEST DISCONTINUITY THAT YOU
COULD FIND IN A STEEL SPECIMEN WITH A VELOCITY OF
6KM/SEC USING A TRANSDUCER WITH A FREQUENCY OF 3
MEGAHERTZ (MHz).
6 X 10 CM/SEC5
3 Mhz= 2 MILLIMETERS=
IF THE SMALLEST DEFECT DETECTABLE IS ½ LAMBDA. THEN
THEANSWER IS 1 MILLIMETER OR 0.040 INCHES.
Lesson 2
UT Lecture Guide
-14-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A The distance between two displacements is called the WAVELENGTH. This is
the distance a wave advances white a particle makes one complete cycle.B The symbol used to represent a wavelength “ ” is called LAMBDA.C The wavelength is a ratio of a fixed value (VELOCITY) divided by a variable
(FREQUENCY).
WAVELENGTH = ------------------- or = ----------
UT LESSON 2WORKSHEET
VELOCITY
FREQUENCY
v
f
D For the purpose of this exercise, consider that the smallest discontinuity
detectable using pulse echo testing is one half lambda.1. What is the smallest defect you can detect with a 2 Mhz probe inspecting a
steel specimen with a velocity of 60 x 10 cm/sec? = (answer in inches)
(1 mm equals . 040 )
5
-
2. What is the smallest detect could detect if you increased the probe
frequency to 5 Mhz? (Answer in inches)
3. What probe below would detect the smallest detect if you were inspecting a
steel specimen with a velocity of 5.9 x 10 cm/sec?What is the smallest each of the below would detect? (Answer in inches)______ 2.5 Mhz______ 5.0 Mhz______ 10.0 Mhz
5
4. With everything else equal. Would a wavelength be longer in water or steel?
-15-
1. Relative to ultrasonic testing, air is considered a good conductor and for
ths reason ultrasound will carry long distances in air.2. Particle density of a material has a direct relationship to the velocity of
sound in that material.3. The symbol used to represent a wavelength is called “Shepda.”4. With everything else equal, the wavelength in water would be shorter than
a wavelength in steel.5. To understand our definition of ultrasonics, a steel ball is considered to be
more elastic than a lead ball6. Man can hear sound up to approximately 5.000.000 Hz.7. Vibration pass through a solid material as a series of particle
displacements.8. The velocity of sound is slower in steel than in water.9. The number of cycles in a given period of time is called the frequency.10. For the purposes of this lesson, ½ the wavelength is considered to be the
smallest discontinuity that can be detected with ultrasonics.
11. If the longitudinal velocity in aluminum is 6.5 x 10 cm/sec and you are
using a 2.5 MHz probe, what is the smallest discontinuity you can detect?
(3 pts)
12. The ability of a transducer to convert mechanical energy to electrical and
electrical energy to mechanical is due to the _______________ effect.13. The distance that an ultrasonic pulse travels while a particle makes one
complete cycle is called ______________
5
UT LESSON 2QUIZ
-16- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ULTRASONIC EQUIPMENT
LESSON 3
MARKERCIRCUIT
TIMER(RATE
GENERATION)
SWEEPCIRCUIT
TRANSDUCER
(TO EACH CIRCUIT)
TESTSPECIMEN
DISCONTINUITY
BACK REFLECTION
POWERSUPPLY
PULSERCIRCUIT
RECEIVERAMPLIFIER
CIRCUIT
CRT
THE ULTRASONIC PULSE ECHO INSTRUMENT GENERATES HIGH VOLTAGE
ELETRICALPULSES OF SHORT DURATION. THESE PUYLSESAREAPPLIED TO
THE TRANSDUCER WHICH CONVERTS THEM INTO MECHANICAL
VIBRATIONS THATAREAPPLIED TO THE MATERIALBEING INSPECTED.
A LARGE PERCENTAGE OF THE SOUND IS REFLECTED FROM THE FRONT
SURFACE OF THE TEST PART BACK TO THE TRANSDUCER. THE
REMAINDER IS REFLECTED BY THE BACK SURFACE OR
DISCONTINUITIES.THE SOUND REFLECTED BACK TO THE TRANSDUCER IS CONVERTED
BACK TO ELECTRICAL PULSES. WHICH ARE AMPLIPIED AND DISPLAYED
ON THE CATHODE RAYTUBE (CRT)AS VERTICALPULSES.
THE AMPLITUDE IS A RELATIVE MEASURE OF THE AMOUNT OF
REFLECTED ENERGY.
THE A-SCAN DISPAY INDICATES THE DEPTH AND THE AMPLITUDE OF THE
SOUND REFLECTIONS FROMADISCONTINUITY.
-17-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THEREARE TWO BASIC ULTRASONIC TEST SYSTEMS:
PULSE-ECHO
COUPLANT
SPECIMEN
DISCONTINUITY
GENERATOR/INDICATORINSTRUMENT COAXIAL CABLE
TRANSDUCERTRANSMITTING
CATHODE-RAY TUBE
THROUGH TRANSMISSIONRECEIVINGTRANSDUCER
COUPLANT
THROUGH TRANSMISSION SYSTEM
CATHODE-RAY TUBE
TRANSDUCER
COAXIAL CABLEGENERATOR/INDICATORINSTRUMENT
PULSE-ECHO SYSTEM
COUPLANT
SPECIMEN
DISCONTINUITY
Lesson 3
UT Lecture Guide
-18-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
PULSE-ECHO IS THE MOST WIDELY USED ULTRASONIC SYSTEM.SHORT EVENLY TIMED PULSES OF ULTRASONIC WAVES ARE
TRANSMITTED INTO THE MATERIALS BEING TESTED.THESE PULSES REFLECT FROM DISCONTINUITIES IN THEIR PATH, OR
FROMANY BOUNDARYTHATTHEY STRIKE.THE RECEIVED REFLECTIONSARE THEN DISPLAYED ONACATHODE RAY
TUBE (CRT)THE SAME TRANSDUCER CAN BE USED TO TRANSMITAND RECEIVE.
THROUGH TRANSMISSION REQUIRES THE USED OF TWO TRANSDUCERS,
ONE FOR SENDINGAND THE OTHER FOR RECEIVING.EITHER SHORT PULSES OR CONTINUOS WAVES ARE TRANSMITTED INTO
THE MATERIAL.THE QUALITY OF THE MATERIAL BEING TESTED IS MEASURED IN TERMS OF
ENERGY LOST BYASOUND BEAMAS ITTRAVELS THROUGH THE MATERIAL
WHERE THE TRANSDUCER IS COUPLED TO THE
MATERIALTHROUGH THIN LAYER OF COUPLANT.BOTH THE MATERIAL AND THE TRANSDUCER ARE
IMMERSED INATANK OF COUPLANT (USUALLY WATER).
THEREARE TWO TEST METHODS NORMALLY USED IN ULTRASONIC TESTING
"CONTACT TESTING"
" IMMERSION TESTING ".
Lesson 3
UT Lecture Guide
-19-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
TO DETERMINE THE LOCATION OF DISCONTINUITIES WITHIN A TEST PART,
THE CRT HORIZONTAL DISPAY IS DEVIDED INTO CONVENIENT INCREMENTS
SUCHAS CENTIMETERS, INCHES, ETC.
AT A GIVEN SESNSITIVITY THE AMPLITUDE OF THE PIP IS
DETERMINED BY THE STRENGTH OF THE SIGNAL GENERATED BY THE
REFLECTED SOUND WAVE.THUS,1.2.
FOCUS AND ASTIGMATISM COTROLS. ADJUST THE SHARPNESS OF THE
DISPLAYED SIGNALS
SENSITIVITY OR GAIN CONTROLS. DETERMINE THE AMOUNT OF
AMPLIFICATION THE SIGNALS FROM THE DISCONTINUITY RECIEVED.INCREASING THE SENSITIVITY (GAIN) INCREASES THE AMPLITUDE OF THE
PIPS ON THE CRT SCREEN.
(GAIN) SETTING.
THE CRT DISPLAYS TWO TYPES OF INFORMATION:DISTANCE (TIME) OF THE DISCONTINUITY FROM THE TRANSDUCERRELATIVE MAGNITUDE OF THE REFLECTED ENERGY
1 2 3 41 2 3 4
A B
4"
Lesson 3
UT Lecture Guide
-20-
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TWO CONTROLS, THE "SWEEP LENGTH" AND "SWEEP DELAY" REGULATE
HOW MUCH OF THE TEST PART IS DISPLAYED AT ONE TIME ON THE CRT, AND
WHAT PORTION OF THE PART IS DISPLAYED.THE SWEEP LENGTH (MATERIAL CONTROL) EXPANDS OR COMPRESSES
THE DISPLAY ON THE CRTAS SHOWN BELOW:
THE SWEEP DELAY CONTROLALLOWS ONE TO MOVE THE VIEWING SCREEN
ALONG THE DEPTH OF THE TEST PART.IN IMMERSION TESTING, THE SWEEP DELAY CAN BE USED TO REMOVE THE
INITIALPULSE FROM THE CRT.
1 IN. 4 0 F T
EXPANDED SWEEP
VIEW A
COMPRESSED SWEEP
VIEW B
A - INITIAL PULSEB - FRONT SURFACE PIPC - 1 BACK SURFACE REFLECTION PIP
ST
A
BC
VIEW A VIEW B
A A BC
B
C
Lesson 3
UT Lecture Guide
-21-
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"PULSE REPETITION RATE" CONTROL REGULATES HOW OFTEN THE PULSE
IS APPLIED. PULSE RATES VARY FROM 50 TO 1200 PULSES PER SECOND OR
MORE.
WHEN THE SWEEP IS LONG, THE PULSE RATE MUST BE LOWER TOALLOW
ENOUGH TIME FOR THE SWEEP TO BE DISPLAYED BEFORE ANOTHER
PULSE IS TRANSMITTED.
IN SOME INSTRUMENTS THE PULSE RATE IS ADJUSTED AUTOMATICALLY.
INCREASING THE PULSE LENGTH INCREASES THE AMOUNT OF SOUND
ENERGY APPLIED TO THE TEST PART. BUT DECREASES THE RESOLVING
POWER OF THE EQUIPMENT.THE "PULSE ENERGY" MUST BE INCREASED TO OBTAIN DEEP
PENETRATION OR TO PENETRATE COARSEGRAINED MATERIALS.THE "REJECT CONTROL" OR "SUPPRESSION CONTROL" IS USED TO
ELIMINATE OR REDUCE "GRASS" OR VERY LOW AMPLITUDE PIPS ALONG
THE BASE OF THE SWEEP LINE. THIS CONTROL MAY AFFECT THE
VERTICALLINEARITY OF THE PRESENTATION.
A "FLAW ALARM" OR "GATING CIRCUIT" IS USED TO ESTABLISH ZONES
ALONG THE SWEEP LINE WITHIN WHICH PIPS OF PREDETERMINED
AMPLITUDE WILLACTIVATE EITHERANALARM ORARECORDING SYSTEM.
AB
CA
B C
ALARM AMPLITUDE
END OF GATESTART OF GATE
VIEW A VIEW B
Lesson 3
UT Lecture Guide
-22-
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“DISTANCE AMPLITUDE CONTROL” . ULTRASONIC TESTING THEAMPLITUDE OF THE PIP FROM A DISCONTINUITY OF A GIVEN SIZEDECREASES AS THE DEPTH INCREASES. TO COMPENSATE FOR THIS“ATTENUATION,” AN ELECTRONIC CONTROL HAS BEEN ADDED TO MANYULTRASONIC UNITS.
SOME OF THE COMMON NAMES FOR THIS CONTROL ARE:DAC - DISTANCE AMPLITUDE CORECTIONTCD - TIME CORRECTED GAINSTC - SENSITIVITY TIME CONTROL
THIS CONTROL IS VERY USEFUL WHEN USED IN CONDUCTION WITHTHE FLAW ALARM AND WITH RECORDING SYSTEMS.
WITHOUT DAC
WITH DACWITH DAC
Lesson 3
UT Lecture Guide
-23-
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A. As shown below, many ultrasonic units have 50 divisions along the base line of
the CRT screen. By using the simple formula below, we can make the distance
across the screen represent any distance we wish from about 5 inches to over
100 inches.The formula used to find the value of each division on the screen below is:
UT LESSON 3WORKSHEET #1
Increment/Division =Range x 2
100
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
EXAMPLE: If you wanted the entire screen to represent 10, we would find that by
using the formula that, each division on the base line represents 0.2
Inc/Div =10 x 2 20
100 100= 02”=
B. After you have selected a suitable screen range it is than possible to use the
sweep controls and match the pulses on the CRT to a know thickness calibration
block. This will be discussed in later lessons.C. Many Ultrasonic units have 100 divisions across the base line instead of 50 in
this case simply divide the range by 100 to find the increment per division.D. On the next page rill in the CRT screens as instructed.
-24-
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On the CRT screens below, draw in the left edge of the first back reflection and at least
one multiple the back echo as if would appear using a normal beam transducer on a
properly calibrated unit
UT LESSON 3WORKSHEET #1
A
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
B
D
C
E
F
SCREEN RANGE - 1 inchPART THICKNESS - 0.49”
SCREEN RANGE - 25”PART THICKNESS -
SCREEN RANGE - 1”PART THICKNESS - 3/16”
SCREEN RANGE - 20”PART THICKNESS - 6
SCREEN RANGE - 2.5”PART THICKNESS - .6B”
SCREEN RANGE - 50”PART THICKNESS - 10
-25-
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Name _______________________________
UT LESSON 3
WORKSHEET #2
Calculate the depth to each pulse on the CRT screens below. Consider that a normal
beam transducer was used on a properly calibrated unit.
A
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
If The above CRT is calibrated toa 25° range, what is the distanceto the pulse? ____________
B
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
If The above CRT is calibrated to a25° range, what is the distance tothe pulse? ____________
C
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
If The above CRT is calibrated toa 2.5° range, what is the distanceto the pulse? ____________
D
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
If The above CRT is calibrated toa 2.5° range, what is the distanceto the pulse? ____________
E
0 1 2 4 53
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
If The above CRT is calibrated to a2.5° range, where would the pips fora two discontinuities and backcohoes shear as shown is Fig. 1?
EACH SQUARE REPRESENTS 1/4°Fig. 1
F
-26-
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________ 1. With “Through Transmission”, an increase in amplitude indicates the presence of
a possible discontinuity.________ 2. The “Pulse Echo” system uses a continuous wave and a separate transducer
receives the echo.________ 3. Both contact testing and immersion testing require the use of a coupling medium.________ 4. Typically, the “gain” control will determine the amount of amplification for a
suspected discontinuity indication.________ 5. Sweep length and sweep delay are two names for the same control.________ 6. The sweep length control is often used to sweep the initial pulse off the CRT in
immersion testing.________ 7. In the a-scan presentation used in contact testing, the height of the vertical
deflection (pip) on the CRT represents:A. VelocityB. Elapsed timeC. DistanceD. Signal amplitude
________ 8. The “distance amplitude correction” control has the ability to automatically
increase the screen range when a thicker part is inspected.________ 9. On the CRT “A” below, draw in the pulse if a normal beam transducer were used
to show a 9° deep continuity using a 15° screen range. How many division from
the left?___________ (3 pts)
________ 10. On the CRT “B” below, what is the distance to the pulse if a 2.5° screen range
were being used for the inspection? ___________ (3 pts)
Name _______________________________
UT LESSON 3
QUIZ
-2-10-1-2
-2-10-1-2
0 1 2 3 4 5
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 3 4 5
0 1 2 3 4 5 6 7 8 9 10
A B
-27-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
MODES OF ULTRASONIC WAVELTRAVEL
VELOCITY CAN BE DEFINED AS THE DISTANCE A WAVE WILL PROPOGATETHROUGHAMEDIUM INAGIVEN UNIT OF TIME, USUALLYASECOND.THE WAVE SPEED REMAINS CONSTANTTHROUGHAGIVEN MEDIUM.
LISTED BELOW IS A TABLE OF IMPEDANCE, VELOCITY AND DENSITYVALUES.THIS INFORMATION WILL BE USEFUL LATER IN THIS LESSON FORPERFORMING BASIC ULTRASONIC CALCULATIONS.
ULTRASONIC WAVES ARE REFLECTED WHEN THEY ENCOUNTER A MEDIUMOF A DIFFERENT ACOUSTICAL IMPEDANCE. THE “SURFACE” AT WHICH THISREFLECTION OCCURS IS CALLEDAN “INTERFACE”.AN INTERFACE IS THE COMMON BOUNDARY BETWEEN TWO MATERIALS ORPHASES, SUCH AS ALUMINUM-TO-STEELOR WATER-TO STELL.
POINT B
POINT A
STEEL
TRANSOUCER
OIL COUPLANT
PULSES
ACOUSTIC SOUND
MATERIAL
AIR
WATER
ALUMINUM
STEEL
IMPEDANCE
(GRAM)CM - SEC2
VELOCITY
(CM /SEC)2
DENSITY
(GRAM/CM )3
0.000033 X 10
0.149 X 10
1.72 X 10
4.56 X 10
6
6
6
6
0.001
1.00
2.71
7.8
Lesson 4
-28-
0.33 X 10
1.49 X 10
6.35 X 10
5.85 X 10
5
5
5
5
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A BEAM OF ENERGY APPROACHING AN INTERFACE IS REFERRED TO ASAN “INCIDENT WAVE”.
THE ANGLE AT WHICH THE WAVE STRIKES THE INTERFACE IS KNOW ASTHE “ANGLE OF INCIDENT” AS SHOWN BELOW
THE INCIDENT WAVE IS SAID TO HAVE NORMAL INCIDENCE WHEN ITSDIRECTION OF PROPAGATION IS PERPENDICULAR TO AN INTERFACE.
AS SHAWM BELOW THE ANGLE OF INCIDENCE IS ZERO.
SOME OF THE WAVE ENERGY STRIKING AN INTERFACE WILL BETRANSMITTED THROUGH THE INTERFACE, AND SOME WILL BEREFLECTED AT THE ANGLE OF INCIDENCE.
THE AMOUNT OF REFLECTION DEPENDS ON THE ACOUSTIC IMPEDANCERATIO BETWEEN THE TWO MEDIA INVOLVED THIS REFLECTANCE WILLFACTOR WILL BE DISCUSSED IN DETAIL IN THE NEXT LESSON.
INCIDENT WAVE
IMAGINARYPERPENDICULARLINE
INTERFACE
INCIDENT WAVE
INTERFACE
NORMAL INCIDENCE
Lesson 4
UT Lecture Guide
-29-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ANGLE OF REFLECTION AT AN INTERFACE OR BOUNDARYALWAYS EQUALS THE ANGLE OF INCIDENCE ANGLE = ANGLE “B”
ULTRASONIC VIBRATIONS TRAVEL IN MANY MODES. AND THEMOST COMMON ARE:
1. LONGITUDINAL (COMPRESSION)2. SHEAR (TRANSVERSE)3. SURFACE (RAYLEIGH)4. PLATE (LAMB)
EACH WAVE MODE HAS A SPECIFIC FUNCTION IN ULTRASONICINSPECTION AND IT IS IMPORTANT THAT EACH BE UNDERSTOODCOMPLETELY
INCIDENT WAVE
NORMALINCIDENCE
ANGLE OF REFLECTION
REFLECTED WAVE
INTERFACE
INTERFACE OR BOUNDARY
A
B
TRANSDUCER
COUPLANT
INCIDENT WAVE
REFLECTED WAVE
IMAGINARY LINE
Lesson 4
UT Lecture Guide
-30-
A B
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LONGITUDINAL (COMPRESSIONAL) WAVES HAVE PARTICLE VIBRATIONS IN ABACKAND FORTH MOTION IN THE DIRECTION OF WAVE PROPAGATION.
CONSIDER THAT ALL MATERIALS ARE MADE UP OF ATOMS LINED UP INSTRAIGHT LINES TO FORM A LATTICE STRUCTURE. WHEN STRIKING THESIDE OF THE LATTICE, A CHAIN REACTION OF PARTICLE MOVEMENT ISSTARTED CAUSING THE LONGITUDINALWAVE
MEDIUM
(SHEAR WAVES)(SHEAR WAVES)
DIRECTION OF PROPAGATIONDIRECTION OF PROPAGATION
PARTICLE MOTIONPARTICLE MOTION
DIRECTION OF PROPAGATIONDIRECTION OF PROPAGATION
LONGITUDINAL WAVES
MEDIUM
PARTICLE MOTIONPARTICLE MOTION
SHEAR (TRANSVERSE) WAVES HAVE PARTICLE VIBRATIONSPERPENDICULAR TO THE DIRECTION OF WAVE MOTION.
SHEAR WAVES WILLNOTTRAVELTHROUGH LIQUIDS OR GASSES.IN SOME MATERIALS, VELOCITY OF A SHEAR WAVE IS ABOUT ½ THAT OF
LONGITUDINAL WAVES. THEREFORE, THE WAVELENGTH IS SHORTER(ABOUT ½)PERMTTING SMALLER DISCONTINUITIES TO BE LOCATED.
Lesson 4
UT Lecture Guide
-31-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ULTRASONIC ANGLE BEAM TRANSDUCER USES THE FOLLOWINGEXAMPLE THE “REFRACTED” SHEAR WAVES ARE USEFUL IN MANYINSPECTION TECHNIQUES.
THE “ANGLE OF REFRACTION” IS THE ANGLE FORMED BETWEEN AREFRACTED BEAM AS IT ENTERS THE SECOND MEDIUM AND A KLINEDRAWN PERPENDICULAR TO THE INTERFACE.
MODE CONVERSION TAKES PLACE WHENASOUND BEAM HITSAN INTEFACEBETWEEN TWO DIFFERENT MEDIAATANANGLE OTHER THAN 90 DEGREES.MODE CONVERSION IN THE CASE PRESENTED BELOW PRODUCES TWOREFLECTED BEAM:ONE BEAM CONSISTS OF LONGITUDINAL WAVES. THE OTHER BEAMCONSISTS OF SHEAR WAVES.
TRANSDUCER
GREASE COUPLANT
STEEL BLOCKINCIDENT BEAM(LONGITUDINAL WAVES)
AIR
REFLECTED BEAM (LONGITUDINAL WAVES) REFLECTED BEAM (SHEAR WAVES)
NORMALINCIDENCE
INCIDENT BEAM(LONGITUDINAL) ANGLE
OF
INCIDENCE
INTERFACE
ANGLE OF REFLECTION (LONGITUDINAL)
REFLECTED BEAM(LONGITUDINAL WAVES)
REFRECTED BEAM (SHEAR WAVES)
ANGLE OF REFRECTION (SHEAR)
PLASTIC
STEEL
Lesson 4
UT Lecture Guide
-32-
SNELL’S LAW CAN BE USED TO DETERMINE ANGULAR RELATIONSHIPSBETWEEN MEDIAFOR BOTH LONGITUDINALAND SHEAR WAVES.
V
V
SIN
SIN 2
1
2
1
=
= ANGLE OF INCIDENCE= VELOCITY IN FIRST MEDIUM= ANGLE OF REFRACTION= VELOCITY IN SECOND MEDIUM
1
V1
V2
2
THE FOLLOWING EXAMPLE CALCULATES THEANGLE OF REFRACTIONALONGITUDINALWAVE PASSING THROUGHAWATER TO-STEELINTERFACE.
10 DEGREES =ANGLE OF INCIDENCE1.49 KM/SEC = LONGITUDINALVELOCITY IN WATER (V )
5.85 KM/SEC = LONGITUDINALVELOCITY IN STEEL(V )
FOR
1
2
2
2
FIRST MEDIUM (WATER)
SECOND MEDIUM (STEEL)
V1
V2
2
1
V1
V2
sin
sin2
1
V2
=
=V1
(sin )sin
sin
sin
2
2
2
2
1
=
=
=
1 . 49
1 . 012
0 . 6791
42 46'o
Lesson 4
UT Lecture Guide
-33- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
AS THE ANGLE OF INCIDENCE INCREASES, THE ANGLE OF REFRACTIONINCREASES.
WHEN THE REFRACTION ANGLE OF A LONGITUDINAL WAVE REACHES 90DEGREES, THE WAVE EMERGES FROM THE SECOND MEDIUM ANDTRAVELS PARALLELTO THE INTERFACE OR SURFACE.THIS IS CALLED ITS FIRST OR LOWER "CRITICAL ANGLE" ABOVEAPPROXIMATELY 28 DEGREES WITH A PLASTIC-TO-STEEL INTERFACE,ONLY SHEAR WAVESARE GENERATED IN THE PART.
ANGLEOF INCIDENCE
PLASTIC
STEEL
REFRACTEDLONGITUDINALWAVE
REFRACTED SHEARWAVE
IF THE ANGLE OF INCIDENCE IS INCREASED PAST THE FIRST CRITICALANGLE, ONLYASHEAR WAVE IS GENERATED IN THE PART. WHEN THEANGLEOF REFRACTION FOR THE SHEAR WAVE IS 90 DEGREES, THEN WE HAVEREACHED THE UPPER OR SECOND CRITICAL ANGLE WHICH PRODUCESSURFACE WAVES,
AS SHOWN BELOW, THERE IS THEN TOTAL REFLECTION FOR BOTHLONGITUDINALAND SHEAR WAVES.WITH A PLASTIC-TO-STEEL INTERFACE. THIS HAPPENS ATAPPROXIMATELY 58 DEGREES
9 0O
ANGLEOF INCIDENCE
PLASTIC
STEELREFRACTED SHEARWAVE
9 0O
28O
28O
(SURFACE WAVE)
REFLECTED LONGITUDINALWAVE
Lesson 4
UT Lecture Guide
-34-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
WHEN THE INCIDENT BEAM IS AT ITS SECOND CRTITICAL ANGLE, A THIRDTYPE OF WAVE IS DEVELOPED, CALLEDARAYLEIGH OR SURFACE WAVE.
AS SHOWN BELOW, THE WAVE TRAVELS WITH AN ELLIPTICAL PARTICELMOTION.SURFACE WAVES ARE USEFUL IN DETECTING SURFACE CRACKS, BUTONLY PENETRATEABOUT ONE WAVELENGTH.
PARTICLEMEDIUM'S SURFACE
PARTICLE MOTION
SURFACE WAVES
DIRECTION OF PROPAGATION
AS SHOWN, SURFACE WAVES HAVE THE ABILITY TO FOLLOW THE SURFACECONTOUR AS LONG AS THE CONTOUR DOES NOT SHARPLY CHANGE.HOWEVER, THE SURFACE WAVE CAN BE ALMOST COMPLETELY ABSORBEDBY EXCESS COUPLANT OR BY TOUCHING YOUR FINGER TO THE SURFACEOF THE PARTAHEAD OF THE TRANSDUCER.
TRANSDUCER
TEST SPECIMEN
DISCONTINUITY
WEDGE
Lesson 4
UT Lecture Guide
-35-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
PLATE WAVES OR LAMB WAVES HAVE THE ABILITY TO PROPAGATETHROUGH THIN PLATES IN A VARIETY OF WAVE MODES DEPENDING ONPLATE THICKNESS, TRANSDUCER. FREQUENCYAND INCIDENTANGLE.
PLATE WAVESARE GENERATED BY USING LONGITUDINALWAVES WHICHDEVELOP EITHER SYMMETRICAL ORASYMMETRICAL WAVESAS SHOWNBELOW.PLATE WAVES OCCUPY THE ENTIRE THICKNESS OF THE PART. WITHOUT"SATURATING" THE PART, THE WAVE CANNOT EXIST.
TO GENERATED PLATE WAVES, YOU ADJUST THE INCIDENT ANGLE TO THEPOINT THAT MAXIMUM REFLECTIONS ARE OBSERVED ON THE CRT SCREENFROMAKNOWN REFLECTOR.IT IS NOT POSSIBLE TO GENERATE SHEAR OR SURFACE WAVES ONMATERIALS THINNER THAN ONE-HALF WAVELENGTH. THEREFORE, PLATEWAVEARE USEFULAS SHOWN BELOW.
TRANSDUCER
HOLLOW EXTRUSION
THIN SHEET OR PLATE
PARTICLE MOTION
DIRECTION OF PROPAGATION
PARTICLE MOTION
THIN SHEET OR PLATE
SYMMETRICAL
PLATE WAVES
ASYMMETRICAL
Lesson 4
UT Lecture Guide
-36-
DIRECTION OF PROPAGATION
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A. Using snell’s Law and the attached Sine table, calculate the following refractionproblems, using the information in the sketch below.
Name _______________________________
UT LESSON 4
WORKSHEET #1
1
2
LUCITE
(long. Velocity 2.73 x 10 cm/sec)5
STEEL ( long. Velocity 5.9 x 10 cm/sec)( shear velocity 3.23 x 10 cm/sec)
5
5
________ 1. Find the refracted longitudinal wave if the incident angle Ø is 25 degrees.
(SHOW WORK) (2 pts)
________ 2. Find the refracted shear wave angle if the incidence angle is 45 degrees.
(SHOW WORK) (2 pts)
________ 3. If you wanted a shear wave to travel into the steel at 70 degrees, what would the
incident angle through the lucite be? (SHOW WORK) (2 pts)
________ 4. If Ø = 18º, is it possible to have a refracted longitudinal wave?
If yes, what is it? (SHOW WORK) (2 pts)If no, why not?
________ 5. If Ø = 36°, is it possible to have a refracted longitudinal wave?
If yes. what is it?If no. Why not?
1
1
1
-37-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
UT LESSON 4
WORKSHEET #1
Angle Cos Tan Angle Sin Cos Tan
1*
2*
3*
4*
5*
6*
7*
8*
9*
10*
11*
12*
13*
14*
15*
16*
17*
18*
19*
20*
21*
22*
23*
24*
25*
26*
27*
28*
29*
30*
31*
32*
33*
34*
35*
36*
37*
38*
39*
40*
41*
42*
43*
45*
.0175
.0349
.0523
.0698
.0872
.1045
.1219
.1392
.1564
.1736
.1908
.2079
.2250
.2419
.2588
.2756
.2924
.3090
.3256
.3420
.3584
.3746
.3907
.4067
.4226
.4384
.4540
.4695
.4848
.5000
.5150
.5299
.5446
.5592
.5736
.5878
.6018
.6157
.6293
.6428
.8561
.6691
.6820
6947
.7071
.9998
.9994
.9986
.9976
.9962
.9945
.9925
.9903
.9877
.9848
.9816
.9781
.9744
.9703
.9659
.9613
.9563
.9511
.9455
.9397
.9336
.9272
.9205
.9135
.9063
.8988
.8910
.8829
.8746
.8660
.8572
.8480
.8387
.8290
.8192
.8090
.7986
.7880
.7771
.7660
.7547
.7231
.7314
7193
.7071
.0175
.0349
.0524
.0699
.0875
.1051
.1228
.1405
.1584
.1763
.1944
.2126
.2309
.2493
.2679
.2867
.3057
.3249
.3443
.3640
.3839
.4040
.4245
.4452
.4663
.4877
.5095
.5317
.5543
.5774
.6009
.6249
.6494
.6745
.7002
.7265
.7536
.7813
.8098
.8391
.8893
.9004
.9325
.9657
1.0000
46*
47*
48*
49*
50*
51*
52
53
54
55*
56*
57*
58*
59*
60*
61*
62*
63*
64*
65*
66*
67*
68*
69*
70*
71*
72*
73*
74*
75*
76*
77*
78*
79*
80*
81*
82*
83*
84*
85*
86*
87*
88*
89*
90*
*
*
*
.7193
.7314
.7431
.7547
.7660
.7771
.7880
.7986
.8090
.8192
.8290
.8387
.8480
.8572
.8660
.8740
.8829
.8910
.8988
.9063
.9135
.9205
.9272
.9336
.9397
.9455
.9511
.9563
.9613
.9659
.9703
.9744
.9788
.9816
.9848
.9877
.9900
.9925
.9945
.9962
.9976
.9986
.9994
.9898
1.0000
.6947
.6820
.6691
.6561
.6428
.6293
.6157
.6018
.5878
.5736
.5992
.5446
.5299
.5150
.5000
.4848
.4695
.4540
.4384
.4226
.4067
.3907
.3746
.3584
.3420
.3256
.3090
.2924
.2757
.2588
.2419
.2250
.2079
.1908
.1736
.1564
.1392
.1219
.1045
.0872
.0698
.0523
.0349
.0175
.0000
1.0355
1.0724
1.1108
1.1504
1.1918
1.2349
1.2799
1.3270
1.3764
1.4281
1.4826
1.5399
1.6013
1.6643
1.7321
1.8040
1.8807
1.9626
2.0503
2.1445
2.2460
2.3559
2.4751
2.6051
2.7475
2.9042
3.0777
3.2709
3.4874
3.7321
4.0108
4.3315
4.7046
5.1446
5.6713
6.3138
7.1154
8.1443
9.5144
11.4301
14.3007
19.0811
28.6363
57.2900
-38-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 1. An “ultrasonic beam” travels trough a medium as waves of sound energy.________ 2. Normal incidence is when the incident beam is parallel to the interface.________ 3. The reflection of an incident beam at an interface is equal to its angle of reflection.________ 4. Particle vibration in a longitudinal wave is in the direction of wave propagation.________ 5. Shear wave velocity is approximately twice the velocity of longitudinal waves.________ 6. Mode conversion occurs when a sound beam strikes an interface between two
media of different velocities at an angle.________ 7. The bending of an incident beam as it passes through an interface is called
refraction.________ 8. Longitudinal waves will propagate through both solids and liquids.________ 9. Both plate waves and surface waves can follow the part contour.
Shear velocity in steel = 3.23 x 10 cm/secLong. Velocity in steel = 5.85 x 10 cm/sec.Long. Velocity in water = 1.49 x 10 cm/secLong. Velocity in lucite = 2.73 x 10 cm/sec
USING THEABOVE INFORMATION, SOLVE THE FOLLOWING PROBLEMS.INDICATE THE APPROXIMATE ANGLES ON THE SKETCH AND LABEL
EACH.
________ 10. If you wanted a shear wave to travel into steel at 60 degrees, what would be the
incident angle on the lucite wedge? (SHOW WORK) (3 pts)
________ 11. What would be the refracted longitudinal wave if the angle of incidence through a
water to steel interface is 12 degrees? (SHOW WORK) (3 pts)
5
5
5
5
Name _______________________________
UT LESSON 4
QUIZ
Sin O1
2V
=
Sin O
1
2
V
60
120
-39-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
UT LESSON 4
QUIZ
Angle Cos Tan Angle Sin Cos Tan
1*
2*
3*
4*
5*
6*
7*
8*
9*
10*
11*
12*
13*
14*
15*
16*
17*
18*
19*
20*
21*
22*
23*
24*
25*
26*
27*
28*
29*
30*
31*
32*
33*
34*
35*
36*
37*
38*
39*
40*
41*
42*
43*
45*
.0175
.0349
.0523
.0698
.0872
.1045
.1219
.1392
.1564
.1736
.1908
.2079
.2250
.2419
.2588
.2756
.2924
.3090
.3256
.3420
.3584
.3746
.3907
.4067
.4226
.4384
.4540
.4695
.4848
.5000
.5150
.5299
.5446
.5592
.5736
.5878
.6018
.6157
.6293
.6428
.8561
.6691
.6820
6947
.7071
.9998
.9994
.9986
.9976
.9962
.9945
.9925
.9903
.9877
.9848
.9816
.9781
.9744
.9703
.9659
.9613
.9563
.9511
.9455
.9397
.9336
.9272
.9205
.9135
.9063
.8988
.8910
.8829
.8746
.8660
.8572
.8480
.8387
.8290
.8192
.8090
.7986
.7880
.7771
.7660
.7547
.7231
.7314
7193
.7071
.0175
.0349
.0524
.0699
.0875
.1051
.1228
.1405
.1584
.1763
.1944
.2126
.2309
.2493
.2679
.2867
.3057
.3249
.3443
.3640
.3839
.4040
.4245
.4452
.4663
.4877
.5095
.5317
.5543
.5774
.6009
.6249
.6494
.6745
.7002
.7265
.7536
.7813
.8098
.8391
.8893
.9004
.9325
.9657
1.0000
46*
47*
48*
49*
50*
51*
52
53
54
55*
56*
57*
58*
59*
60*
61*
62*
63*
64*
65*
66*
67*
68*
69*
70*
71*
72*
73*
74*
75*
76*
77*
78*
79*
80*
81*
82*
83*
84*
85*
86*
87*
88*
89*
90*
*
*
*
.7193
.7314
.7431
.7547
.7660
.7771
.7880
.7986
.8090
.8192
.8290
.8387
.8480
.8572
.8660
.8740
.8829
.8910
.8988
.9063
.9135
.9205
.9272
.9336
.9397
.9455
.9511
.9563
.9613
.9659
.9703
.9744
.9788
.9816
.9848
.9877
.9900
.9925
.9945
.9962
.9976
.9986
.9994
.9898
1.0000
.6947
.6820
.6691
.6561
.6428
.6293
.6157
.6018
.5878
.5736
.5992
.5446
.5299
.5150
.5000
.4848
.4695
.4540
.4384
.4226
.4067
.3907
.3746
.3584
.3420
.3256
.3090
.2924
.2757
.2588
.2419
.2250
.2079
.1908
.1736
.1564
.1392
.1219
.1045
.0872
.0698
.0523
.0349
.0175
.0000
1.0355
1.0724
1.1108
1.1504
1.1918
1.2349
1.2799
1.3270
1.3764
1.4281
1.4826
1.5399
1.6013
1.6643
1.7321
1.8040
1.8807
1.9626
2.0503
2.1445
2.2460
2.3559
2.4751
2.6051
2.7475
2.9042
3.0777
3.2709
3.4874
3.7321
4.0108
4.3315
4.7046
5.1446
5.6713
6.3138
7.1154
8.1443
9.5144
11.4301
14.3007
19.0811
28.6363
57.2900
-40-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
COUPLANTSAND ULTRASONIC SOUND ENERGY
THE PRIMARY PURPOSE OFACOUPLANT IS TO PROVIDEASUITABLE SOUNDPATH BETWEEN THE TRANSDUCERAND THE TEST SURFACE.
A COUPLANT MUST EFFECTIVELY WET OR TOTALLY CONTACT BOTHSURFACES OF THE TRANSDUCERAND TEST PART.
1. THE COUPLANT MUST EXCLUDE ALL AIR FROM BETWEEN THESURFACESASAIR ISAVERY POOR CONDUCTOR OF SOUND.
2. THE COUPLANT FILLS IN AND SMOOTHS OUT IRREGULARITIES ONTHE SURFACE OF THE TEST PART.
3. THE COUPLANT AIDS IN THE MOVEMENT OF THE TRANSDUCEROVER THE SURFACE IN CONTACTTESTING.
4. A PRACTICAL COUPLANT MUST BE AESY TO APPLY AND EASY TOREMOVE IT MUSTALSO BE HARMLESS TO THE PART SURFACE.
OIL OR WATER MIXED WITH GLYCERINE (2 PARTS WATER AND 1 PARTGLYCERINE) ARE COMMONLY USED COUPLANTS. EVEN WALLPAPER PASTEHASADVANTAGESASACOUPLANT.
HEAVER COUPLANTS, SUCH S GREASE OR HEAVY OIL CAN BE USED ONROUGH OR VERTICALSURFACES.SPECIALLY FORMULATED LIQUID AND PASTE COUPLANTS ARE ALSOAVAILABLE FROM ULTRASONIC EQUIPMENT MANUFACTURERS.
IN CIRCUMSTANCES WHERE THE USE OF LIQUIDS OR PASTE ISUNDESIRABLE, THIN RUBBER OR RUBBER-LIKE MATERIALS MAY BE USED.
IN ALL CASES THE COUPLANT SHOULD BE AS THIN AS POSSIBLE IF THECOUPLANT IS EXCESSIVE, IT MAY ACT AS A WEDGE AND ALTER THEDIRECTION OF THE SOUND BEAM.
TRANSDUCER
COUPLANT
TEST MATERIAL
Lesson 5
-41-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE SURFACE OF A TEST SPECIMEN CAN GREATLY AFFECT ULTRASONICWAVE PROPAGATION.ROUGH SURFACE CAN CAUSE UNDESIRABLE EFFECTS SUCH ASREDUCTION OF DISCONTINUITY AND BACK SURFACE AMPLITUDES DUE TODISTORTION OF WAVE DIRECTIVITY.
COUPLANT
UNEVEN BUT CONSISTANT
SURFACEFLAT SMOOTH SURFACE ROUGH AND IRREGULAR
SURFACE
COUPLANT
FAIR TEST POOR
FRONT SURFACE
(INITIAL PULSE)
WIDE
FRONT SURFACE
BACK SURFACE
DISCONTINUITY REDUCED
AMPLITUDE
MARKERS
FLAT SMOOTH SURFACE - GOOD RESPONSE
CRT INDICATIONS
A-SCAN PRESENTATION
(PULSE-ECHO)
ROUGH AND IRREGULAR SURFACE-POOR RESPONSE
Lesson 5
UT Lecture Guide
-42-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A GOOD BACK SURFACE REFLECTION INDICATES A GOOD RESPONSE FROMTHE MATERIAL BEING TESTED. IT IS REFLECTED BACK TO ITS SOURCESSIMILAR TO LIGHT STRIKINGAMIRROR.
IF THE SURFACESARE NOT PARALLEL, THE REFLECTED ENERGY WILL BEDIRECTEDAWAY FROM THE TRANSDUCER SIMILAR TO LIGHT FALLING ONAMIRRORATANANGLE.
FRONT SURFACE
(INITIAL PULSE)
TRANSDUCER
FRONT SURFACE
SPECIMEN
CROSS-SECTION
REFLECTION
BACK SURFACE CRT INDICATIONS
REDUCEDBACK SURFACE
INDICATION
THE PHYSICAL SHAPE OR CONTOUR OF A PART MUST BE CONSIDEREDWHENATTEMPTING TO DISCERN WHETHERADISCONTINUITY INDICATION ISREALOR FALSE.
EXAMPLES OF SOUND PATHS LEADING TO SPURIOUS INDICATIONS
IN TESTING LONG SPECIMENS, REFLECTION F A SPREADING BEAM CANPRODUCE FALSE INDICATIONS ON THE CRTAS SHOWN BELOW
A SHEAR WAVE MAY BE GENERATED WHICH IS REFLECTED AT A STEEPANGLE TO THE OPPOSITE SIDE, WHERE MODE CONVERSION TAKESPLACE. MODE CONVERSION WILL BE DISCUSSED IN A LATER LESSON.HOWEVER, THIS TYPE OF FALSE SIGNAL WILL APPEAR ON THE RIGHTSIDE OF THE FIRST BACK ECHO.
LONGITUDINAL WAVE
TRANSDUCER
SHEAR WAVE
SPECIMEN
DIAMETER
FIRST BACKLONGITUDINAL WAVE
Lesson 5
UT Lecture Guide
-43-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
GRAIN STRUCTURE HAS A GREAT INFLUENCE ON THE ACOUSTICALPROPERTIES OFAMATERIAL
A STEEL FORGING GENERALLY HAS A FINE GRAIN STRUCTURE AND HASALOW DAMPING EFFECT ON THE SOUND BEM.HOWEVER, A CASTING GENERALLY HAS A COARSER GRAIN STRUCTUREWHICH IS MOE DIFFICULTTO GET SOUND THROUGH.
FRONT SURFACEDISCONTINUITY
FINE GRAIN
BACK SURFACE
REFLECTION
COARSE GRAIN
BACK SURFCEREFLECTIONLOST OR REDUCED
FRONT SURFACE
WHENADISCONTINUITY IS NOT NORMAL (AT 90 DEGREES) TO THE INCIDENTWAVE THE REFLECTED WAVE WILLBEATANANGLE.
AS SHOWN BELOW, THE RESULT IS A REDUCTION IN THE AMPLITUDE OFTHE DISCONTINUITY INDICATION DISPLAYED ON THE CRT.
POSITION C
POSITION B
POSITION A
CRACK
CYLINDRICAL SPECIMEN
POSITION A POSITION B POSITION C
AT POSITION “A”ABOVE, THERE ISASHARP DISCONTINUITY INDICATIONANDLITTLE BACK SURFACE INDICATION. AT POSITION “C” THE DISCONTINUITY SAT MINIMUM, OR MAY NOT BE SEENATALL.
Lesson 5
UT Lecture Guide
-44-
TWO BASIC TECHNIQUES ARE USED IN LOCATING AND EVALUATING ANGULARFLAWS.
1. CONTACTTESTING UTILIZESAN “ANGLE BEAM” TRANSDUCER WITHA PLASTIC WEDGE TO CHANGES THE DIRECTION OF WAVEPROPAGATION.
2. IMMERSION TESTING USES WATER AS A COUPLANT, TILTING THETRANSDUCER TOACHIEVE THE NECESSARY DIRECTIONALITY.
THE SHAPE OR SURFACE CONDITION OF A DISCONTINUITY INFLUENCES THEINDICATION ON THE CRT.A DISCONTINUITY HAVING A ROUGH SURFACE WILL TEND TO SCATTER THEREFLECTIONAS COMPARED TOASMOOTH FLAW.NONMETALLIC INCLUSIONS ARE TYPICAL ROUGH AND WOULD SCATTER THESOUND MORE THANACRACK-LIKE DISCONTINUITY.
Lesson 5
UT Lecture Guide
ANGLE BEAMTRANSDUCER
PLASTIC WEDGE
SPECIMEN
CONTACT TESTING
SPECIMEN
PROBE TRANSDUCER
IMMERSION TESTING
WATERTANK
-45- External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
AIR IS A POOR MEDIUM FOR TRANSFERRING ULTRASONIC VIBRATIONSINTO LIQUIDS OR SOLIDS. THEREFORE, A COUPLANT MUST BE USED TOTRANSFER ENERGY FROM HE TRANSDUCER TO THE TEST MATERIAL.
WATER ISACOMMONLY USED COPLANTAS SHOWN BELOW:
WATER
TRANSDUCERPRINCIPAL DIRECTIONOF SOUND BEAM
SECODARY LOBER
SECODARY LOBER
MOST OF THE ULTRASONIC ENERGY IS CONCENTRATED ALONG THECENTERLINE OF THE BEAM.THE SECONDARY OR SIDE LOBES FROM AT THE TRANSDUCER FACE ANDRADIATEAWAY FROM THE PRINCIPLE DIRECTION OF SOUND TRAVEL.
THESE SECONDARY LOBES REPRESENT AREAS OF HIGH AND LOWINTENSITIESATTHE EDGE OF THE BEAM.BECAUSE OF THE SECONDARY LOBES, THE USEFUL WIDTH OF ATRANSDUCER BEAM IS-LESS THAN THE TRANSDUCER’S PHYSICALWIDTH.
TRANSDUCER DIAMETER HASADEFINITE INFLUENCE ON THE SOUND BEAMTRANSMITTED THROUGHAMEDIUM.FOR A GIVEN FREQUENCY, A SMALLER TRANSDUCER HAS A GREATER BEAMSPREAD ANGLE THAN A LARGER DIAMETER TRANSDUCER AS SHOWNBELOW:
SMALL DIAMETER
TRANSDUCERMEDIUM
BEAM DIVERGES
LARGE DIAMETERTRANSDUCER
MEDIUM
BEAM CONSTANT
Lesson 5
UT Lecture Guide
-46-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
CHANGING THE TRANSDUCER’S VIBRATING FREQUENCY WILL ALSOCHANGE THE BEAM SPREAD.
DIVERGENCE IS INVERSELY PROPORTIONALTO FREQUENCY.THEREFORE, A HIGH FREQUENCY TRANSDUCER HAS A MORECONSTANT DIAMETER SOUND BEAM THAN A LOW FREQUENCYTRANSDUCER.FREQUENCY OR BY USINGALARGER DIAMETER TRANSDUCER.
THE AMOUNT OF BEAM SPREAD IS DETERMINED BY THE FOLLOWINGEQUATION:
HALF
POWER
POINT (. 707 OF INTENSITY)
= WAVELENGTH
= DIAMETER
= HALF-ANGLE OF
= BEAM SPREAD TO
= HALF-POWER POINT
DSIN O = 1.22
WHERE
D
O
THE BEAM SPREAD OF A ½ INCHDIAMETER, 1 Mhz TRANSDUCER ISSHOWN TO BE 34 DEGREES.REMEMBER THAT WAVELENGTH ( ) ISDETERMINED BY DIVIDING THEVELOCITY BY THE FREQUENCY.TO CHANGE INCHES TO CENTIMETERS.MULTIPLY BY 2.54.
0 = 34O
0O
SECONDARY
LOBES
Lesson 5
UT Lecture Guide
-47-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
Name _______________________________
UT LESSON 5
WORKSHEET #1
Understanding “Beam Spread” will help point out importance of selecting the properfrequency and size transducer. The length of the ultrasonic wave and the diameter of thetransducer are often critical in the determination of flaw size and location.Using the information given below, determine the “Beam Spread” for the conditions listed.
(a) Velocity in steel = .585 x 10º cm/sec(b) Velocity in aluminum = .625 x 10º cm/sec(c) One inch = 2.54 centimeters
(D) Wavelength ( ) =
(E) Sin O = 1.22
y Velocity
Frequency
D
y
________ 1. What would be the beam spread using a 1” diameter, 2.25 MHz transducer on an
aluminum test part? (SHOW WORK) (3 pts)
________ 2. What would be the beam spread using a 1” diameter, one MHZ transducer on an
aluminum test part? (SHOW WORK) (3 pts)
________ 3. What would be the beam spread using a one half inch diameter, 2.25 MHz
transducer on a steel test part? (SHOW WORK) (3 pts)
-48-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
UT LESSON 5
WORKSHEET #1
Angle Cos Tan Angle Sin Cos Tan
1*
2*
3*
4*
5*
6*
7*
8*
9*
10*
11*
12*
13*
14*
15*
16*
17*
18*
19*
20*
21*
22*
23*
24*
25*
26*
27*
28*
29*
30*
31*
32*
33*
34*
35*
36*
37*
38*
39*
40*
41*
42*
43*
45*
.0175
.0349
.0523
.0698
.0872
.1045
.1219
.1392
.1564
.1736
.1908
.2079
.2250
.2419
.2588
.2756
.2924
.3090
.3256
.3420
.3584
.3746
.3907
.4067
.4226
.4384
.4540
.4695
.4848
.5000
.5150
.5299
.5446
.5592
.5736
.5878
.6018
.6157
.6293
.6428
.8561
.6691
.6820
6947
.7071
.9998
.9994
.9986
.9976
.9962
.9945
.9925
.9903
.9877
.9848
.9816
.9781
.9744
.9703
.9659
.9613
.9563
.9511
.9455
.9397
.9336
.9272
.9205
.9135
.9063
.8988
.8910
.8829
.8746
.8660
.8572
.8480
.8387
.8290
.8192
.8090
.7986
.7880
.7771
.7660
.7547
.7231
.7314
7193
.7071
.0175
.0349
.0524
.0699
.0875
.1051
.1228
.1405
.1584
.1763
.1944
.2126
.2309
.2493
.2679
.2867
.3057
.3249
.3443
.3640
.3839
.4040
.4245
.4452
.4663
.4877
.5095
.5317
.5543
.5774
.6009
.6249
.6494
.6745
.7002
.7265
.7536
.7813
.8098
.8391
.8893
.9004
.9325
.9657
1.0000
46*
47*
48*
49*
50*
51*
52
53
54
55*
56*
57*
58*
59*
60*
61*
62*
63*
64*
65*
66*
67*
68*
69*
70*
71*
72*
73*
74*
75*
76*
77*
78*
79*
80*
81*
82*
83*
84*
85*
86*
87*
88*
89*
90*
*
*
*
.7193
.7314
.7431
.7547
.7660
.7771
.7880
.7986
.8090
.8192
.8290
.8387
.8480
.8572
.8660
.8740
.8829
.8910
.8988
.9063
.9135
.9205
.9272
.9336
.9397
.9455
.9511
.9563
.9613
.9659
.9703
.9744
.9788
.9816
.9848
.9877
.9900
.9925
.9945
.9962
.9976
.9986
.9994
.9898
1.0000
.6947
.6820
.6691
.6561
.6428
.6293
.6157
.6018
.5878
.5736
.5992
.5446
.5299
.5150
.5000
.4848
.4695
.4540
.4384
.4226
.4067
.3907
.3746
.3584
.3420
.3256
.3090
.2924
.2757
.2588
.2419
.2250
.2079
.1908
.1736
.1564
.1392
.1219
.1045
.0872
.0698
.0523
.0349
.0175
.0000
1.0355
1.0724
1.1108
1.1504
1.1918
1.2349
1.2799
1.3270
1.3764
1.4281
1.4826
1.5399
1.6013
1.6643
1.7321
1.8040
1.8807
1.9626
2.0503
2.1445
2.2460
2.3559
2.4751
2.6051
2.7475
2.9042
3.0777
3.2709
3.4874
3.7321
4.0108
4.3315
4.7046
5.1446
5.6713
6.3138
7.1154
8.1443
9.5144
11.4301
14.3007
19.0811
28.6363
57.2900
-49-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 1. Higher frequency transducer have less beam spread than low frequency
transducers.________ 2. Lower frequency transducers are usually used to find the smaller defects.________ 3. The longer the wavelength ( ). The greater the beam spread and better ability to
locate small discontinuities.________ 4. When comparing two transducer of the same frequency, the larger transducer
will have the greatest beam spread.________ 5. A rough surface on the test specimen may cause a loss in amplitude on the CRT
screen.________ 6. If the front and back surface of a test part are not parallel, there will be a greatly
reduced signal amplitude from any discontinuity in the part.________ 7. Long or thin specimens may cause false indications due to mode conversion of
the longitudinal beam.________ 8. A smooth discontinuity (crack) will reflect more energy than a discontinuity will a
rough surface (inclusion)________ 9. Both contact and immersion testing techniques can be used for performing an
“angle beam” examination of a part.________ 10. The couplant used in ultrasonic inspection should be as thick as possible to
properly direct the sound beam.________ 11. Where a liquid or paste couplant cannot be used, a rubber sheet may sometimes
be used by placing it between the transducer and test part.________ 12. What would be the “Beam Spread” if the following conditions existed?
A. 1” Diameter, 5 MHz transducer.B. Velocity in steel = .585 x 10 cm/sec
C. Sin O = 1.22
D. Wavelength ( ) =
E. One inch
Name _______________________________
UT LESSON 5
QUIZ
y
y
D
YVelocity
frequency
-50-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
UT LESSON 5
QUIZ
Angl Tan Angl Cos Tan
1*
2*
3*
4*
5*
6*
7*
8*
9*
10*
11*
12*
13*
14*
15*
16*
17*
18*
19*
20*
21*
22*
23*
24*
25*
26*
27*
28*
29*
30*
31*
32*
33*
34*
35*
36*
37*
38*
39*
40*
41*
42*
43*
45*
.0175
.0349
.0523
.0698
.0872
.1045
.1219
.1392
.1564
.1736
.1908
.2079
.2250
.2419
.2588
.2756
.2924
.3090
.3256
.3420
.3584
.3746
.3907
.4067
.4226
.4384
.4540
.4695
.4848
.5000
.5150
.5299
.5446
.5592
.5736
.5878
.6018
.6157
.6293
.6428
.8561
.6691
.6820
6947
.7071
.9998
.9994
.9986
.9976
.9962
.9945
.9925
.9903
.9877
.9848
.9816
.9781
.9744
.9703
.9659
.9613
.9563
.9511
.9455
.9397
.9336
.9272
.9205
.9135
.9063
.8988
.8910
.8829
.8746
.8660
.8572
.8480
.8387
.8290
.8192
.8090
.7986
.7880
.7771
.7660
.7547
.7231
.7314
7193
.7071
.0175
.0349
.0524
.0699
.0875
.1051
.1228
.1405
.1584
.1763
.1944
.2126
.2309
.2493
.2679
.2867
.3057
.3249
.3443
.3640
.3839
.4040
.4245
.4452
.4663
.4877
.5095
.5317
.5543
.5774
.6009
.6249
.6494
.6745
.7002
.7265
.7536
.7813
.8098
.8391
.8893
.9004
.9325
.9657
1.0000
46*
47*
48*
49*
50*
51*
52
53
54
55*
56*
57*
58*
59*
60*
61*
62*
63*
64*
65*
66*
67*
68*
69*
70*
71*
72*
73*
74*
75*
76*
77*
78*
79*
80*
81*
82*
83*
84*
85*
86*
87*
88*
89*
90*
*
*
*
.7193
.7314
.7431
.7547
.7660
.7771
.7880
.7986
.8090
.8192
.8290
.8387
.8480
.8572
.8660
.8740
.8829
.8910
.8988
.9063
.9135
.9205
.9272
.9336
.9397
.9455
.9511
.9563
.9613
.9659
.9703
.9744
.9788
.9816
.9848
.9877
.9900
.9925
.9945
.9962
.9976
.9986
.9994
.9898
1.0000
.6947
.6820
.6691
.6561
.6428
.6293
.6157
.6018
.5878
.5736
.5992
.5446
.5299
.5150
.5000
.4848
.4695
.4540
.4384
.4226
.4067
.3907
.3746
.3584
.3420
.3256
.3090
.2924
.2757
.2588
.2419
.2250
.2079
.1908
.1736
.1564
.1392
.1219
.1045
.0872
.0698
.0523
.0349
.0175
.0000
1.0355
1.0724
1.1108
1.1504
1.1918
1.2349
1.2799
1.3270
1.3764
1.4281
1.4826
1.5399
1.6013
1.6643
1.7321
1.8040
1.8807
1.9626
2.0503
2.1445
2.2460
2.3559
2.4751
2.6051
2.7475
2.9042
3.0777
3.2709
3.4874
3.7321
4.0108
4.3315
4.7046
5.1446
5.6713
6.3138
7.1154
8.1443
9.5144
11.4301
14.3007
19.0811
28.6363
57.2900
-51-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ATTENUATION,ACOUSTIC IMPEDANCE,AND RESONANCEAS SHOWN BELOW, A BEAM OF SOUND ENERGY WILL SPREADS OUT(DIVERGE) AS IT MOVES THROUGH THE SPECIMEN, AND THE INTENSITY(ENERGY) DECREASES WITH DISTANCEAWAY FROM THE TRANSDUCERANDAWAY FROM THE CENTER OF THE BEAM.
FORAGIVEN SIZE TRANSDUCERHIGH FREQUENCY TRANSDUCERS PRODUCE NARROWER SOUND BEAMSTHAN LOW FREQUENCYTRANSDUCERS.FOR THE PURPOSE OF ILLUSTRATION, ULTRASONIC SOUND CAN BEVIEWED AS A NARROW CONE-SHAPED BEAM WHICH IS DIVIDED INTO TWOZONES.THE INTENSITY IN THE NEAR ZONE VARIES IRREGULARLY DUE TO SOUNDWAVE INTERACTION CLOSE TO THE TRANSDUCER. THIS PREVENTSRELIABLE DETECTION OF DISCONTINUITIES CLOSE TO THE SURFACE.IN THE FAR ZONE, THE INTENSITY (ENERGY) DECREASES STEADILY DUE TOBOTHATTENUATIONAND BEAM SPREAD
THE INTENSITY AT POINT “Y” ABOVE IS LESS THAN AT POINT “X”.ATTENUATION IS THE TERM USED TO DESCRIBE THIS CONDITION OFENERGY LOSS. ATTENUATION MEANS THE PROCESS OF LESSENING THEAMOUNT.THE PRIMARY REASONS FOR ATTENUATION ARE ABSORPTION ANDSCATTERING OF THE ULTRASONIC ENERGY.
TRANSDUCER(TRANSMITTER)
NEARZONE
FAR ZONE
SPECIMEN (MATERIAL)
TRANSDUCER
(RECEIVER)YX
Lesson 6
-52-
TRANSDUCER
NEAR ZONESPECIMENT
4O
12O
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ATTENUATION IS DIFFERENT IN DIFFERENT MATERIALS, DEPENDING ONTHE ABSORPTION AND SCATTERING OF THE SOUND ENERGY, ANOTHERPHENOMENON WHICH PERTAINS TO THE INTERRELATIONSHIP OF THESOUNDAND MATERIAL PROPERTIES (S “ACOUSTIC IMPEDANCE.” THIS TERMSHOULD NOT BE CONFUSED WITH “ATTENUATION.”“ACOUSTICAL IMPEDANCE” (Z) IS DEFINED AS THE PRODUCT OF THEDENSITY ( )AND SOUND VELOCITY (V) WITHINAGIVEN MATERIALIMPEDANCE = DENSITY X VELOCITY, OR Z = VIMPEDANCE VALUES FOR TYPICALMATERIALSARE SHOWN BELOW:
MATERIAL
IMPEDANCE
(GRAM/CM - SEC)2
VELOCITY
(CM/SEC)
DENSITY
(GRAM/CM )3
AIR
WATER
ALUMINUM
STEEL
0.000033 X 106
0.149 X 106
1.72 X 106
4.56 X 106
0.33 X 105
1. 49 X 105
6.35 X 105
5.85 X 105
0.001
1.00
2.71
7.8
ATTENUATION IS DEFINED AS THE LOSS OF ENERGY (ACOUSTIC) PER UNITOF DISTANCE. FOR ULTRASONIC WAVE PROPAGATION, THE ATTENUATIONCONSTANT IS GIVEN BY:
I2
I1
= e-2
WHERE =ATTENUATION CONSTANT
I2
I1
= RATIO OF INTENSITIESATTWO POINTS A UNIT DISTANCEAPART
I > I1 2
Lesson 6
UT Lecture Guide
-53-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
IF ACOUSTIC ENERGY IS TRANSMITTED INTO TWO PICES OF PERFECTLYBONDED INDENTICAL STEEL, WE FIND THE SOUND HAS THE SAMEVELOCITYTHROUGH BOTH, WITHAN IMPEDANCE RATIO OF 1 TO 1.
TRANSDUCER
STEEL
SOUND BEAM
VELOCITY REMAINS CONSTANT
STEEL
AN IMPEDANCE RATIO OFANYTHING LESS OR GREATER THAN 1 TO 1 IS LESSTHAN IDEAL.AS SHOWN BELOW A LARGE PORTION OF THE SOUND BEAM FROM A WATERTO STEEK INTERFACE WILL REFLECT BACK TOWARDS THE TRANSDUCERAND NEVER ENTER THE PART.
TRANSDUCER
SOUND BEAM
STEEL
WATER
TO DETERMINE HOW MUCH OF THE ENERGY IS REFLECTED YOU CAN USETHE FOLLOWING FORMULA:
REFLECTION FACTOR (R) =
Z =ACOUSTICALIMPEDANCE
IN THE ILLUSTRATION ABOVE , HOW MUCH OF THE SOUND ENERGY ISREFLECTED FROM THE WATER TO STEELINTERFAACE?
Z1 2
Z2
Z2
Z1
-
+
4. 56 - .149
4. 56 + .149
2
R =
24.411
4.709= = 88 PERCENT REFLECTED
Lesson 6
UT Lecture Guide
-54-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
RESONANCE CAN BE DEFINED AS THE CHARACTERISTIC OF A VIBRATINGBODYTO RESONATE OR VIBRATE IN SYMPATHY WITHAVIBRATION SOURCE.
AS SHOWN BELOW, A RESONANT CONDITION WILL EXIST ANY TIME ACONTINOUS LONGITUDINAL WAVE IS INTRODUCED INTO A SPECIMEN ANDREFLECTED "IN PHASE" WITH THE INCOMING WAVE.
COUPLANT
TRANSDUCERSTANDING WAVE
RESONANCE WILL OCUR ONLY WHEN THE THICKNESS OF A SPECIMEN ISEQUAL TO A HALF-WAVELENGTH OR AN EXACT MULTIPLE OF A HALF-WAVELENGTH. SHOWN BELOW IS A "FUNDAMENTAL FREQUENCY" ANDMULTIPLES CALLED "HARMONICS"
TRANSDUCER
TEST SPECIMEN REFLECTED WAVE
INCIDENT WAVE
THICKNESS = 1/2 WAVELENGTH
THICKNESS = 1 WAVELENGTH
THICKNESS = 1-1/2 WAVELENGTH
1
(FUNDAMENTAL FREQUENCY)MHz
2
(2ND HARMONIC)MHz
3
(3RD HARMONIC)MHz
Lesson 6
UT Lecture Guide
-55-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ULTRASONIC UNITS USING THE PRINCIPLE OF RESONANCE WERECOMMONLY USED FOR THICKNESS MEASUREMENT AND BOND ORLAMINATION INSPECTION.
HOWEVER, PULSE-ECHO UNITS HAVE BEEN REFINED TO PERFORM MOSTOF THESE FUNCTIONSAND RESONANT INSTRUMENTSARE RARELY USED.
RESONANCE OCCURS WHEN THE MATERIAL THICKNESS IS EQUAL TO AHALF-WAVENGTH OR EXACT MULTIPLES.
THE WAVELENGTH CAN BE CHANGED BY VARYING THE FREQUENCY
THE FUNDAMENTAL RESONANT FREQUENCY IS THE FREQUENCY AT WHICHASPECIMEN WILLRESONATE.
HARMONICS ARE EXACT MULTIPLES OF THE FUNDAMENTAL (MINIMUM)RESONANT FREQUENCY.
THE FUNDAMENTALRESONANT FREQUENCY CAN BE FOUND BY:
F =V
2T F = FUNDAMENTAL RESONANT FREQUENCYV = VELOCITY OF LONGITUDINAL WAVET = THICKNESS OF MATERIAL
"A" "B"MATERIAL TRANSDUCER
STANDING WAVE
DISCONTINUITY
AS SHOWWN ABOVE IN "A" THE FREQUENCY HAS BEEN ADJUSTED UNTIL ASTANDING WAVE "RESONANCE" HAS BEEN ESTABLISHED.
IF THE TRANSDUCER IS MOVED TO POSITION "B" THE MATERIAL WILL STOPRESONATING UNTIL THE FREQUENCY (WAVELENGTH) IS ADJUSTED TOAGAIN ESTABLISH RESONANCEAS SHOWN.
Lesson 6
UT Lecture Guide
-56-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
Name _______________________________
UT LESSON 6
WORKSHEET #1
A. Using the information given below, solve the problems relating to “reflection factors”.B. The chart below lists the common impedance values.
(IMPEDANCE = VELOCITY X DENSITY)
MATERIALDENSITY(GRAM / CM )
3
IMPEDANCE(GRAM/CM - SEC)
2
VELOCITY(CM / SEC)
0.000033 X 106AIR
WATER
ALUMINUM
STEEL
1.72 X 106
0.149 X 106
4.56 X 106
0.33 X 105
1.49 X 105
6.35 X 105
5.85 X 105
0.001
1.00
2.71
7.8
C. Reflection factor =Z1
2-
+
Z Z
Z
1
2
2
Z. = Acoustic Impedance
Water
Aluminum
1Z
Z2
________ 1. What percentage of the original sound energy will be reflected back to the probe
at the water to aluminum interface? (SHOW WORK) (3 pts)
________ 2. What percentage of the original sound energy will finally enter the water on its
way back to the transducer from the back surface of the aluminum part? (SHOW
WORK) (3 pts).Only consider the reflection factors, do not consider the normal attenuation that
would occur in the material it self.
-57-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 3. A clad material is to be tested for bond defects. One material has a thickness of
0.3 inches and an acoustic impedance of 5.0 x 10 gram/cm - second and the
other material is 4.0 inches thick and has an acoustic impedance of 4.
________ 4. Would you inspect the bonded material through the thick side or through the thin
side? Why? (2 pts)
________ 5. On the CRT screen below, using a 5 inch screen range, sketch the approximate
location and amplitude of the pips from an acceptable bond condition. (2 pts)
• As a general rule, “R” should be less than 20% for adequate bond inspection.
2 2
5 x 10
gram/cm - second.If the bond is perfect and acceptable, what percentage of sound would you
expect to be reflected from the interface? (SHOW WORK) (3 pts)
2
2
Name _______________________________
UT LESSON 6
WORKSHEET #1 (continued)
-2-10-1-2
-2-10-1-2
0 1 2 3 4 5
0 1 2 3 4 5 6 7 8 9 10
-58-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 1. The gradual loss of energy as a sound beam travels through a material is called
attenuation.________ 2. Whenever possible, the UT inspection should be done in the “near zone” before
the sound can spread out and attenuated.________ 3. “Acoustic Impedance” refers to resistance of sound propagation through a part.________ 4. Compared to steel, air has a very high acoustic impedance value.________ 5. The original ultrasonic velocity remains the same regardless of the media it is
passing through.________ 6. A sound beam with a given energy will travel farther in aluminum than in steel
before it is attenuated by the same amount.________ 7. A fine grained material will usually caused less attenuation than a coarse grained
material.________ 8. The terms “Intensity” and Impendence” mean the same thing.________ 9. In immersion testing, it is typical that less than 1% of the original sound energy is
returned to the transducer.________ 10. Using the information given below, what would be the reflection Factor at the
interface shown between the water (Z ) and steel (Z )? (SHOW WORK) (3 pts)1 2
Name _______________________________
UT LESSON 6
QUIZ
Reflection Facto (R) =Z - Z1 2
Z + Z1 2
2
=
Z = Acoustic Impedence
STEEL Z2TRANSDUCER WATERZ 1
CRACK BEAM
MATERIALDENSITY(GRAM / CM )
3
IMPEDANCE(GRAM/CM - SEC)
2
VELOCITY(CM / SEC)
0.000033 X 106AIR
WATER
ALUMINUM
STEEL
1.72 X 106
0.149 X 106
4.56 X 106
0.33 X 105
1.49 X 105
6.35 X 105
5.85 X 105
0.001
1.00
2.71
7.8
-59-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
DISPLAYING ULTRASONIC INDICATIONS
THERE ARE THERE BASIC TYPES OF VISUAL DISPLAYS WHICH ARE
COMMONLY USED TO EVALUATE THE SOUNDNESS OR QUALITY OF A
MATERIALBEING TESTED;A-SCAN, B-SCANAND C-SCAN.
A-SCAN IS A "TIME VERSUS AMPLITUDE" DISPLAY WHICH REVEALS A
DISCONTINUITY USINGA"PIP" ONACATHODE-RAYTUBE (CRT).
AMPLITUDE
INITIALPULSE
BACK SURFACEREFLECTION
DISCONTINUITY
HORIZONTAL SWEEP
TIME
THEA-SCAN PRESENTATION,AS HAS BEEN DISCUSSED, IS READ FROM LEFT
TO RIGHT. THE HEIHT OF A PIP CAN BE COMPARED TO THE HEIHT OF A PIP
FROM A KNOWN REFERENCE REFLECTOR TO GIVE AN INDICATION OF
RELATIVE DISCONTINUITY SIZE.
AMPLITUDE
TRANSDUCER
DISCONTINUITY
MATERIAL
INITIAL PULSE DISCONTINUITYINDICATION
BACK SURFACEREFLECTION
A-SCAN PRESENTATION
HORIZONTAL SWEEP
Lesson 7
-60-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
B-SCAN PRESENTATION, AS SHOWN BELOW, TYPICALLY USES AN
OSCILLOSCOPE SCREEN TO DISPLAY A CROSS-SECTIONAL VIEW OF THE
MATERIALBEING TESTED.
THE IMAGE IS RETAINED ON THE CRT LONG ENOUGH TO EVALUATE THE
SAMPLE AND TO PHOTOGRAPH THE SCREEN FOR A A PERMANENT
RECORD.
C-SCAN ISA"PLAN VIEW" PRESENTATION SIMILAR TOAN X-RAY PICTURE.
AS SHOWN BELOW, THE C-SCAN SHOWNS THE SHAPE AND LOCATION OF
THE DISCONTINUITY, BUT DOES NOT SHOW THE DEPTH.
DISCONTINUITIES
B-SCAN PRESENTATION
THICKNESS OF
TEST MATERIAL
FRONT SURFACE
BACK SURFACE
DISCONTINUITIES
C-SCAN PRESENTATION
Lesson 7
UT Lecture Guide
-61-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
HIGH SPEED ULTRASONIC SCANNING GENERALLY UTILIZES THE C-SCAN
PRESENTATION.
AS SHOWN BELOW, SOME RECORDERS USE A CHEMICALLY TREATED
PAPER. THE PAPER MOVEMENT IS SYNCHRONIZED WITH THE MOVEMENT
OF THE TRANSDUCERACROSS THE TEST SURFACE.
THE ADNANTAGE OF THE C-SCAN IS ITS SPEED AND ABILITY TO PRODUCE A
PERMANENT RECORD. HOWEVER, THE SCAN SHOWS ONLY LENGTH AND
WIDTH, BUT NOT DEPTH.
PRINT BAR
SCAN LINES
DISCONTINUITY
RECORDING PAPER FEED
HELIX DRUM
MOTION OFTRANSDUCER
DISCONTINUITY
Lesson 7
UT Lecture Guide
-62-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
A TYPICAL BRIDGE/MANIPULATOR IS SHOWN FOR A BASIC ULTRASONIC
IMMERSION TEST.
WHEN A C-SCAN IS TO BE MADE, ELECTRIC MOTORS ARE UTILIZED TO
ACTIVATE THE TRAVELING MECHANISMS AND THE UP AND DOWN
MOVEMENT OF THE SEARCH TUBE.
A TYPICAL A-SCAN PRESENTATION IS SHOWN BELOW USING CONTACT
TESTING WITHANANGLE BEAM TRANSDUCER
THE PROCEDURE USED TO CALIBRATE THE UT UNIT IS SIMILAR TO NORMAL
BEAM TESTING AND REQUIRES A CALIBRATION BLOCK WITH A KNOWN SIZE
REFLECTION SURFACEATAKNOWN METALTRAVEL
TANK WITH MOTORIZED BRIDGE
CARRIACE ORBRIDGE
TEST SPECIMEN
SCANNER TURBE
MANIPULATOR
TRANSDUCER
SUPPORT FOR TEST SPECIMEN
CRT
DISCONTINIUTY
SHEARWAVES
ANGLE BEAM TRANSDUCER
A
B
Lesson 7
UT Lecture Guide
-63-
A B
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ACALIBRATION BLOCK (IIW TEST BLOCK FURTHER DISCUSSED IN LESSON 8)
IS SHOWN BELOW WITH A KNOW DISTANCE OF A INCHES TO THE CURVED
SURFACE.
USING THE SWEEP AND DELAY CONTROLS, THE PIPS ARE ADJUSTED TO
SHOWN MULTIPLES OF 4 INCHES ON THE CRT.
IF THE MINATURE ANGLE BEAM CALIBRATION BLOCK SHOWN BELOW WERE
USED TO CALIBRATE THE ABOVE CRT SCREEN, WHERE WOULD THE PIPS
APPEAR?
DEPENDING ON THE DIRECTION OF THE ANGLE BEAM PROBE, THE PIPS
WOULD EITHER APPEAR AT ONE, FOUR, AND SEVEN INCHES OR TWO, FIVE,
AND EIGHT INCHES.
1” 2”
MINIATURE ANGLE BEAM
0 2 4 6 8 10
NOTCH4 “
Lesson 7
UT Lecture Guide
-64-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ANGLE BEAM TECHNIQUE IS OFTEN USED FOR WELD INSPECTION AS
SHOWN BELOW.
2nd 4th
3rd1st
LEGLEG
LEG LEG
1 st skip distance(”V” PATH)
2 nd skip distance(”V” PATH)
TYPICALLY, THE WELD SHOULD BE INSPECTED IN THE 1 ST OR 2 ND LEG
WHENEVER POSSIBLEAS SHOWN BELOW.
SKIPDISTANCE
VIEW A VIEW B VIEW C
TO ASSIST IN EVALUATING THE RESULTS OF ANGLE BEAM INSPECTION, A
DIRECT READING ULTRASONIC CALCULATOR IS COMMONLY USED.
THE HORIZONTAL SCALEACROSS THE TOP OF THE CARD REPRESENTS THE
NUMBER OF INCHES BETWEEN THE TRANSDUCERAND THE CENTER OF THE
WELD.THE VERTICAL SCALE REPRESENTS SPECIMEN THICKNESS AND THE ARC
SHOWN THEANGLE OF THE SOUND BEAM.
40
50
60
70
80
1
2 3 4 5 6 7 8 9 101
2
1
2
0
Lesson 7
UT Lecture Guide
-65-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE FOLLOWING IS AN EXAMPLE OF A TYPICAL ANGLE BEAM INSPECTION
USING THE ULTRASONIC CALCULATOR.ADOUBLE VEE WELD WITHAN OPENING OF 30 DEGREES INA2” STEELPLATE
USINGA60 DEGREE SHEAR WAVE IN THE SPECIMEN.
DISCONTINUITY
DASHED LINEPOINT OF INCIDENCE B
A
1 2 3 4 5 6 7 8 9 100
1
2
3 4
5
6
7
2
11
2
4050
60
70
80
THE FOLLOWING PROCEDURE SHOULD BE USED IN SETTING UP THE
CALCULATOR:1. DRAW A LINE REPRESENTING THE SOUND PATH FROM THE UPPER
LEFT CORNER THROUGH THE 60 DEGREE MARK ON THE ARC,
EXTENDING TO THE 2 - POINT REPRESENTING THE PLATE
THICKNESS. CALIBRATE THE HORIZONTAL SWEEP OF THE CRT TO
REPRESENT BEAM TRAVEL DISTANCE IN THE MATERIAL BEING
TESTED.2. TO SHOW THE FULL SKIP DISTANCE OF THE SOUND BEAM, YOU
THEN DOUBLE THE 3 7/16” AND MARK THAT POINT AT
APPROXIMATELY 6 7/8” (POINT “B”ABOVE)3. NEXT, DRAW THE 30 DEGREE FEE WELD ON THE PLASTIC SLIDE OR
TRANSPARENT PAPER THAT SLIDES BACK AND FORTH OVER THE
CALCULATOR.4. AS SHOWN ABOVE, A DISCONTINUITY IS DISPLAYED ON THE CRT
SCREEN AT 5.5”.THE OPERATOR THEN MEASURES THE DISTANCE
BETWEEN THE CENTER OF THE TRANSDUCER (EXIT POINT) AND
THE CENTER OF THE WELDMENT (4 5/8”) AND SLIDES THE
TRANSPARENT PAPER TO THE SAME DISTANCE.5. THE POSITION OF THE DISCONTINUITY IS INDICATED AND CAN BE
EVALUATED.
Lesson 7
UT Lecture Guide
-66-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
Name _______________________________
LESSON 7
WORKSHEET #1
Angle beam inspection requires that the operator understand how the sound beam is
reflected within the specimen. On the CRT screen provided, indicate the location of each
pip based on the sound path distances shown. (3 pts each)
3”
3”
2”
8”
2”
8”
-2-10-1-2
-2-10-1-2
0 1 2 3 4 5
15 INCH SCREEN RANGEA
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 3 4 520 INCH SCREEN RANGEB
0 1 2 3 4 5 6 7 8 9 10
-2-10-1-2
-2-10-1-2
0 1 2 3 4 512 INCH SCREEN RANGEC
0 1 2 3 4 5 6 7 8 9 10
-67-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 1. On a typical B-Scan, the horizontal sweep represents time and the vertical
deflection represents amplitude.________ 2. The B-Scan can display how deep the discontinuity is below surface of the
specimen.________ 3. The typical A-Scan is the display commonly used for recording a permanent
record with the immersion inspection technique.________ 4. The vertical pip on an A-Scan can be used to compare the relative size of a
discontinuity.________ 5. The C-Scan display will indicate length and width of a discontinuity, but it cannot
show death.________ 6. To obtain an A-Scan display with ultrasonic immersion testing, it is necessary to
auto mate the bridge/manipulator with electric motors.________ 7. The “Ultrasonic Calculator” can be used in weld inspection to indicate the
location of a discontinuity in the weldment.________ 8. Whenever possible, the weld should be inspected in the “2nd Skip Distance.”________ 9. The calibration of a UT instrument for sound path distance can be performed
using the curved surface of the “IIW Block”________ 10. To accurately utilize the “Ultrasonic Calculator” it is necessary to accurately
measure the distance from center line of the weld to the exist point of the
transducer.________ 11. Using an E-Screen range on the CRT below, indicate where the “pips” should
appear if the instrument is to be properly calibrated for sound path distance in the
block shown (SHOW WORK) (3 pts).
Name _______________________________
UT LESSON 7
QUIZ
MINIATURE ANGLE BEAM-2-10-1-2
-2-10-1-2
0 1 2 3 4 5
0 1 2 3 4 5 6 7 8 9 10
-68-
1”2”
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
ULTRASONIC TRANSDUCERSAND STANDARD REFERENCE BLOCKS THE
ULTRASONIC TRANSDUCER IS THE HEART OF THE UTTEST SYSTEM.
THE CRYSTAL MATERIAL IN AN ULTRASONIC TRANSDUCER IS MADE OF
PIEZOELECTRIC MATERIAL SUCH AS QUARTZ, LITHIUM SULFATE AND
POLARIZED CERAMICS.1. QUARTZ WAS THE FIRST MATERIAL USED.
CHARACTERISTICS. HOWEVER, QUARTZ IS A POOR
GENERATOR OF ACOUSTIC ENERGY AND HAS GENERALLY BEEN
REPLACED BY MORE EFFICIENT MATERIALS.2. LITHIUM SULFATE IS A VERY EFFICIENT RECEIVER OF ACOUSTIC
ENERGY, BUT IS FRAGILE, SOLUBLE IN WATER AND LIMITED TO USE
ATTEMPERATURES BELOW 165 F.3. POLARIZED CERAMICS PRODUCE THE MOST EFFICIENT
GENERATORS OF ACOUSTICS ENERGY BUT THEY DO HAVE A
TENDENCY TO WEAR. COMMON POLARIZED CERAMICS INCLUDE
B A R I U M T I TA N AT E , L E A D M E TA N I O B AT E , A N D L E A D
ZIRCONATE/TITANATE.THE CAPABILITY OFATRANSDUCER IS DESCRIBED BYTHREE TERMS:
1. SENSITIVITY. THEABILITYTO DETECT SMALLDISCONTINUITIES.2. RESOLUTION. THE ABILITY TO SEPARATE THE SOUND REFLECTIONS
FROM TWO DISCONTINUITIES CLOSE TOGETHER IN DEPTH OR TIME.3. EFFICIENCY. ENERGY CONVERSION EFFECTIVENESS.
IT HAS VERY STABLE
FREQUENCY
O
SEALED CASE
SIGNALCONNECTOR
BACKING
ELECTRODES
GROUNDCONNECTOR
CRYSTAL
Lesson 8
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
SENSITIVITY OF A TRANSDUCER IS RATED BY ITS ABILITY TO DETECT A
CERTAIN SIZE FLAT-BOTTOM HOLE, AT A SPECIFIED DEPTH, IN A STANDARD
REFERENCE BLOCK.
THE SMALLER THE DETECTABLE HOLE, THE GREATER THE SENSITIVITY.
TRANSDUCER SENSITIVITY IS MEASURED BY THE AMPLITUDE OF ITS
RESPONSE FROM AN ARTIFICIAL DISCONTINUITY IN A STANDARD
REFERENCE BLOCK
THE REFERENCE BLOCK IS NECESSARY, BECAUSE EVEN TRANSDUCERS
OF THE SAME SIZE, FREQUENCY AND MATERIAL DO NOT ALWAYS PRODUCE
THE SAME AMPLITUDE SIGNAL FROM A GIVEN REFLECTOR.
TRANSDUCER
REFERENCE
BLOCK
FLAT BOTTOMED HOLE
RESOLUTION IS THE ABILITY TO SEPARATE (DISTINGUISH BETWEEN) THE
SOUND REFLECTIONS FROM A DISCONTINUITY CLOSE TO A BOUNDARY OR
TWO DISCONTINUITIES CLOSE TOGETHER IN DEPTH OR TIME.
INITIALPULSE
BACK SURFACE
REFLECTION
DISCONTINUITY
TIME
POOR RESOLUTION
INITIALPULSE
BACK SURFACE
REFLECTION
DISCONTINUITY
TIME
GOOD RESOLUTION
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
TRANSDUCER MATERIALARE USUALLY CUT IN TWO WAYS:
1. CRYSTALS CUT PERPENDICULAR TO THE X-AXIS PRODUCE
LONGITUDINALWAVES.2. CRYSTALS CUT PERPENDICULAR TO THE Y-AXIS PRODUCE SHEAR
WAVES.
AS SHOWN BELOW, MOST CRYSTALS USED FOR UT ARE CUT
PERPENDICULAR TO THE X-AXIS.
CRYSTAL DEFORMATIONAXIS X-AXIS
Y-AXIS
Z-AXIS
SIZE ISACONTRIBUTING FACTOR IN PERFORMANCE OFATRANSDUCER.1. THE LARGER DIAMETER THE TRANSDUCER, THE LESS THE SOUND
BEAM WILLSPREAD FORAGIVEN FREQUENCY.2. HOWEVER, THE SMALL, HIGH FREQUENCY TRANSDUCER ARE
BETTERABLE TO DETECT VERY SMALLDISCONTINUITIES.3. THE LARGER THE TRANSDUCER, THE MORE SOUND ENERGY IT
TRANSMITS INTO THE TEST PART. LARGE LOW FREQUENCY
TRANSDUCERSARE OFTEN USED TO GET MORE PENETRATION.4. LARGE SINGLE CRYSTAL TRANSDUCERS ARE GENERALLY LIMITED
TO THE LOWER FREQUENCIES. HIGH FREQUENCY CRYSTALS ARE
SUSCEPTIBLE TO DAMAGE BECAUSE THEYARE VERYTHIN.
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE FREQUENCY OF A TRANSDUCER IS AN IMPORTANT FACTOR IN ITS
APPLICATION.
1. THE HIGHER THE FREQUENCY OF A TRANSDUCER, THE LESS THE
SOUND BEAM WILL SPREAD AND THE GREATER THE SENSITIVITY
AND RESOLUTION.WHEN THE SOUND BEAM IS SPREAD AS SHOWN BELOW, LESS
SOUND IS LIKELY TO BE REFLECTED FROM A SMALL
DISCONTINUITY
DISCONTINUITY
HIGH FREQUENCY TRANSDUCER
FIG. 1A
LOW FREQUENCY TRANSDUCER
FIG. 1B
2. THE LOWER THE FREQUENCY, THE DEEPER THE SOUND
PENETRATION AND THE LESS SCATTER. THE GREATER BEAM
SPREAD AIDS IN DETECTING REFLECTORS WHICH ARE NOT
PERPENDICULAR TO THEAXIS OF THE SOUND BEAM.3. CRYSTALS THICKNESS IS ALSO RELATED TO TRANSDUCER
FREQUENCY. THE HIGHER THE FREQUENCY OF THE
TRANSDUCER, THE THINNER THE CRYSTALWILLBE.MOST ULTRASONIC TESTING IS DONE BETWEEN 0.2 MHz AND 25
Mhz AND CRYSTALS CUT FOR USEABOVE 10 MHzARE TO THINAND
FRAGILE FOR CONTACTTESTING.THEREFORE, TRANSDUCERS WITH OPERATING FREQUENCIES
ABOVE 10 MHzARE USED PRIMARILY FOR IMMERSION TESTING.
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
TRANSDUCERS FOR CONTACT TESTING AND IMMERSION TESTING ARE
ESSENTIALLYTHE SAME BUT USUALLYARE NOT INTERCHANGEABLE.
MOST CONTACT TESTING TRANSDUCERS HAVE WEAR PLATES IN FRONT OF
THE PIEZOELECTRIC ELEMENTTO PROTECT IT. THE EXCEPTION TO THIS ISA
QUARTZ TRANSDUCER.
AS SHOWN BELOW, CONTACT TRANSDUCERS CAN BE EITHER “STRAIGHT
BEAM” OR “ANGLE BEAM.”
TRANSDUCER A TRANSDUCER BLUCITE
CERAMIC
STRAIGHT BEAM TRANSDUCERS USUALLY HAVE A LUCITE, CERAMIC, OR
QUARTZ WEAR PLATE IN FRONT OF THE CRYSTAL.
ANGLE BEAM TRANSDUCERS HAVE THE WEAR PLATE WEDGE-SHAPED TO
PRODUCE THE DESIRED REFRACTEDANGLE.
AS SHOWN ABOVE, THE LUCITE WEDGE PROTECTS THE FACE OF THE
CRYSTAL AND DETERMINES THE ANGLE OF INCIDENCE OF THE SOUND
BEAM ON THE TEST PART.
AS HAS BEEN DISCUSSED, WHEN SOUND WAVES ARE DIRECTED INTO THE
TEST PART AT AN ANGLE, THEY ARE DIVIDED INTO LONGITUDINAL AND
SHEAR WAVES BY REFRACTION.MOSTANGLE BEAM TESTING IS DONE WITH SHEAR WAVES.
STRAIGHT BEAM TRANSDUCER ANGLE BEAM TRANSDUCER
LONGITUDINALWAVES
SHEARWAVES
DISCONTINUITY
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ANGLE BEAM PROBE CAN ALSO BE USED TO GENERATE SURFACE
WAVES.
AS WE HAVE DISCUSSED, SURFACE WAVES ARE GENERATED WHEN THE
INCIDENT ANGLE OF THE SOUND BEAM REACHES THE SECOND OR UPPER
CRITICALANGLE.
MOST ANGLE BEAM CONTACT TRANSDUCERS ARE IDENTIFIED. BY THE
REFRACTED SHEAR WAVE PRODUCED (70 , 60 , ETC.), IN A SPECIFIC
MATERIAL, USUALLY STEELANDALUMINUM.
SPHERICALLY GROUND AND CYLINDRICALLY GROUND ACOUSTICAL
LENSES ARE COMMONLY ADDED TO IMMERSION TYPE TRANSDUCERS.
THEYARE USED TO:
1. IMPROVE SENSITIVITYAND RESOLUTION.2. COMPENSATE FOR TEST PART CONTOURS.3. EXAMINEAGIVEN DEPTH OF THE TEST PART MORE CAREFULLY.
AS SHOWN BELOW, CYLINDRICALLY GROUND LENSES FOCUS THE SOUND
ENERGY TO A LINE. SPHERICALLY GROUND LENSES FOCUS THE SOUND
ENERGYTOAPOINT.
O O
WATER
BEAM
METAL
TRANSDUCER
ACOUSTICALLENS
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
CYLINDRICALLENSESARE USED IN TWO WAYS:
1. TO INCREASE THE SENSITIVITYAND RESOLUTION OF EQUIPMENT.2. FOR CONTOUR CORRECTION AS SHOWN BELOW. THE LENS CAN BE
GROUND SPECIALLY TO DIRECT THE SOUND ENERGY NORMAL
(PERPENDICULAR) TOACURVED SURFACEATALLPOINTS.
SPHERICAL LENSES CONCENTRATE THE SOUND ENERGY INTO A CONE
SHAPED BEAM.
1. THE FOCUSING INCREASES ITS INTENSITY, BUT SHORTENS ITS
USEFULRANGE.2. WHILE THE CYLINDERICAL LENS ABOVE HAS A GREATER WIDTH, THE
SPHERICALLENS HAS THE GREATEST SENSITIVITY.3. THE SPHERICAL LENS IS OFTEN USED WHEN IMMERSION TESTING
PARTS HAVINGAROUGH SURFACE.
FOCUSED TRANSDUCERSARE DESCRIBED BYTHEIR FOCALLENGTH.
THE SHORT FOCAL LENGTHS ARE FOR EXAMINING AREAS OF THE
SPECIMEN CLOSE TO THE SURFACE. LONGER FOCAL LENGTHS ARE FOR
INCREASINGLY DEEPER AREAS.
CONTOURCORRECTIONLENS
TUBING
VIEW B
CRT SCREEN DISPLAY
TUBING
VIEW A
FLAT SHOE
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
TRANSDUCERS COME IN MANY SHAPES, SIZES AND PHYSICAL
CHARACTERISTICS.
SOME COMMON TYPES INCLUDE PAINT-BRUSH, DUAL ELEMENT, SINGLE
ELEMENT,ANGLE BEAM, FOCUSED, MOSAIC, CONTACT,AND IMMERSION.
SINGLE ELEMENT TRANSDUCERS MAY BE TRANSMITTERS ONLY,
RECEIVERS ONLY, OR BUTTRANSMITTERAND RECEIVER.
DOUBLE ELEMENT TRANSDUCERS (AS SHOWN BELOW) MAY BE EITHER
SINGLE TRANSDUCERS MOUNTED SIDE BY SIDE OR STAKED.
IN A DOUBLE ELEMENT TRANSDUCER, ONE IS A TRANSMITTER AND THE
OTHERARECEIVER.
SIDE BY SIDE
TRANSMITTER RECEIVER
SOUND BARRIER
STACKED
TRANSMITTERRECEIVER
SOUND BARRIER
DOUBLE ELEMENT TRANSDUCERS HAVE BETTER NEAR SURFACE
RESOLUTION BECAUSE THE RECEIVER CAN RECEIVER DISCONTINUITY
SIGNALS BEFORE THE TRANSMITTER COMPLETES ITS TRANSMISSION.
DISCONTINUITY OBSCUREDBY INITIAL PULSE
SWEEP
MARKER
TRANSDUCER
DISCONTINUITY
TESTSPECIMEN
COAXIAL CABLE
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
STANDARD REFERENCE BLOCKS
IN ULTRASONIC TESTING, DISCONTINUITIES ARE USUALLY COMPARED TO A
REFERENCE STANDARD.
THE STANDARD MY BE ONE OF MANY REFERENCE BLOCKS OR SETS OF
BLOCKS SPECIFIED FORAGIVEN TEST.
REFERENCE BLOCKS COME IN MANY DIFFERENT SHAPES AND SIZES AND
THIS LESSON WILL DISCUSS ONLY A FEW OF THOSE COMMONLY USED. A
TYPICALBLOCKS IS SHOWN BELOW
MOST REFERENCE BLOCKS HAVE THE FOLLOWING IN COMMON:1. THEYARE MADE FROM CAREFULLY SELECTED MATERIAL2. THE MATERIAL MUST HAVE THE PROPERATTENUATION, GRAIN SIZE,
HEATTREATMENTAND BE FREE OF DISCONTINUITIES.3.ALLDIMENSIONS MUST BE PRECISELY MACHINED.4. ALL HOLES MUST BE FLAT-BOTTOMED AND HAVE A SPECIFIED
DIAMETER TO BEAN IDEALREFLECTOR.5. SIDE DRILLED HOLE DIAMETER MUST BE CAREFULLY CONTROLLED.
THREE COMMONLY USED SETS OF STANDARD REFERENCE BLOCKSARE:1.AREAMPLITUDE BLOCKS2. DISTANCEAMPLITUDE BLOCKS3.ASTM BASIC SET OFAREAND DISTANCEAMPLITUDE BLOCKS.
AREAAMPLITUDE BLOCKS PROVIDE STANDARDS FOR DISCONTINUITIES OF
DIFFERENT SIZES,ATTHE SAME DEPTH.
DISTANCE AMPLITUDE BLOCKS PROVIDE STANDARDS FOR
DISCONTINUITIES OF THE SAME SIZEAT DIFFERENT DEPTHS.
A = DIAMETER OF FBHB = METAL DISTANCE
FROM TESTSURFACE TO FBH
C = METAL DISTANCEFROM TESTSURFACE TOBOTTOM OF BLOCK
FLAT-BOTTOM HOLE
TEST SURFACE
B
C
A
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE ASTM BASIC SET OF AREA/DISTANCE AMPLITUDE BLOCKS CONSISTS
OF TEN, TWO INCH DIAMETER BLOCKSAS SHOWN BELOW:
TEST
SURFACE
TARGET
FLAT-BOTTOMHOLE (FB) DIA(SEE TABLE)
METAL DISTANCE(SEE TABLE) 3/4 INCH
METAL DISTANCE, INCHES
FBH DIA IN 64 THS INCH
1/8 1/4 3/4 1-1/2 3 3 3 6 6
5 5 5 5 5 3 5 8 5 8
1 / 2
ANOTHER TYPE OF CALIBRATION BLOCK IS THE IIW BLOCK
(INTERNATIONALINSTITUTE OF WELDING). IT PROVIDES THE FOLLOWING:
VERIFICATION OF DISTANCE KNOWN DISTANCES & ANGULAR
RELATIONSHIPS, VERIFIES TRANSDUCERANGLEAND BEAM EXIT POINTAND
CHECKS TRANSDUCER RESOLUTION.
8” 0.125”
0.25”
3.64”
0.06” HOLE
2” DIAMETER HOLE4”
40” 50” 60”
75”70”60”
FOCAL POINT
12”
4”
PLASTIC INSERT
1”
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
IN CONTACT ANGLE BEAM TESTING, THE BEAM EXIT POINT OF THE
TRANSDUCER MUST BE KNOWN TO ACCURATELY DETERMINE THE
LOCATION OF THE DISCONTINUITY.
AS SHOWN BELOW, THE TRANSDUCER IS MOVED BACK AND FORTH UNTIL
THE PIP ON THE CRT REACHES MAXIMUMAMPLITUDE.
THE FOCAL POINT ON THE IIW BLOCK THEN CORRESPONDS WITH THE BEAM
EXIT POINT OF THE TRANSDUCER.
40”50”60”
75” 70” 60”
ANGLE BEAMTRANSDUCER
BEAM EXIT POINT
FOCAL POINT
SPECIALCALIBRATION STANDARDSSPECIAL STANDARDS ARE OFTEN USED FOR ITEMS SUCH AS WELDMENT,
CASTINGS, AND PIPING. THE STANDARDS ARE NORMALLY OF THE SAME
MATERIAL AND PRODUCT FROM TO BE TESTED. REFERENCE REFLECTORS
SUCHAS NOTCHES OR HOLESAREARTIFICIALLYADDED TO THE STANDARD.
Lesson 8
UT Lecture Guide
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External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
VERIFICATION OF THE TRANSDUCER ANGLE IS ACCOMPLISHED AS SHOWN
BELOW:
THE PLASTIC WEDGE OF THE ANGLE BEAM TRANSDUCER IS SUBJECT TO
WEAR IN NORMAL USE. THIS WEAR CAN CHANGE THE BEAM EXIT POINTAND
THEANGLE OF THE SOUND BEAM.
40” 50” 60”
75”70”60”
60 DEGREE TRANSDUCER
BEAM EXIT POINT
2” DIAMETER HOLE
FROM THE POSITION SHOWN ABOVE, THE TRANSDUCER IS MOVED BACK
AND FORTH UNTIL THE REFLECTION FROM THE 2 INCH HOLE SHOWS
MAXIMUMAMPLITUDE ON THE CRT.
THE ANGLE OF SOUND BEAM CAN THEN BE READ FROM WHERE THE EXIT
POINT ON THE TRANSDUCER MATCHES THE DEGREES STAMPED ON THE
SIDE OF THE BLOCK.
THE TRANSDUCER SOUND BEAM EXIT POINT SHOULDALWAYS BE CHECKED
FIRST. IF THE EXIT POINT MARKING IS NOT CORRECT, THEN THE ANGLE
CHEXK WILLNOT BEACCURATE.
Lesson 8
UT Lecture Guide
-80-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
THE FAR FIELD RESOLVING POWER OF THE TEST EQUIPMENT CAN BE
ESTIMATED BY PLACING A NORMAL BEAM TRANSDUCER ON THE IIW BLOCK
AS SHOWN.
GOOD RESOLUTION WILL BE INDICATED IF THE INSTRUMENT CAN
SATISFACTORILY SEPARATE THE PIPS FROMALLTHREE REFLECTORS
TRANSDUCER
IIW BLOCKCOOD BAD
CRT DISPLAY
THE MINIATUREANGLE BEAM BLOCK CANALSO BE USED TO CALIBRATE THE
INSTRUMENT FORANGLE BEAM INSPECTION.
THE MINIATURE BLOCK IS INTENDED FOR FIELD WORK AND IS NOT AS
COMPREHENSIVEAS THE LARGER IIW BLOCK.
FOCAL POINT
MINIATURE ANGLE BEAM BLOCK
70o
45o
60o
1”
3”
2”
0. 750”
1.75”
0.060” HOLE
0. 750”
Lesson 8
UT Lecture Guide
-81-
External training services : PT. Diametral Dharma PersadaNon Destructive Testing (NDT)
________ 1. The term “resolution” refers to the ability of a transducer to detect a very small
discontinuity.________ 2. Quartz is the only transducer material commonly used that is not a piezoelectric
material.________ 3. If the frequency of a transducer is raised then the beam spread is reduced.________ 4. The polarized ceramic transducer is considered to be a very good generator of
ultrasonic energy.________ 5. Quartz is a type of polarized ceramic transducer material.________ 6. A transducer that can defect a discontinuity close to the surface is saint to have a
good resolving power.________ 7. Larger transducer usually have a higher frequency because they are more
fragile.________ 8. The higher the frequency of a transducer, the smaller the sound cone (i.a. Less
beam spread).________ 9. Immersion testing is always done with transducer that have a frequency between
2.5 and 5.0 MHz.________ 10. Angle beam testing is usually done with longitudinal waves.________ 11. Angle beam probes may be used to generate surface waves.________ 12. A spherical focusing lens will usually have the ability to provide better sensitivity
as compared to a cylinderical lens.________ 13. Focused transducers are often used for shear wave inspection of welded plate
due to the increased penetration.________ 14. A double or dual element transducer can only be used in the longitudinal wave
mode.________ 15. With a double element transducer, the sensitivity is increased because both
elements are receiving and sending sound energy.________ 16. Acoustical tenses increases transducer sensitivity and resolution, but decreases
their useful range.________ 17. Areference block should be made from the same basic material as the part being
tested.________ 18. Blocks which provide a size reference and are used to check the systems
linearity are known as area amplitude blocks.________ 19. The exist point of an angle beam transducer should always be determined before
the angle of the transducer is checked.________ 20. Both the iiw block and miniature block will check the test system resolution.
Name _______________________________
UT LESSON 8
QUIZ
-82-
Recommended