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MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS – 1963
*
*
.
.
*
.
****
LEGAL NOTICE
This report was prepared as an account of
Government sponsored work. Neither the
United States, nor the Commission, nor any
person acting on behalf of the Commission:
A. Makes any warranty or representa-
tion, expressed or implied, with respect to
the accuracy, completeness, or usefulness
of the information contained in this report,
or that the use of any information, appa-
ratus, method, or process disclosed in this
report may not infringe privately owned
rights; or
B. Assumes any liabilities with respect
to the use of, or for damages resulting from
the use of any information, apparatus,
method, or process disclosed in this report.
As used in the above, "person acting on
behalf of the Commission" includes any em-
ployee or contractor of the Commission, or
employee of such contractor, to the extent
that such employee or contractor of the
Commission, or employee of such contractor
prepares, disseminates, or provides access
to, any information pursuant to his employ-
ment or contract with the Commission, or
his employment with such contractor.
OS
ORN-P1542
CONF-650414-6
SEP 20 1965
ORNI -AIC - OFFICIAL
-
.-
MASTER
.-
REFRACTORY-ALLOY
NONDESTRUCTIVE TESTING OF SMALL-DIAMETER/TUBING*
.. -.-
..
K. V. Cook and R. W. McClung
Metals and Ceramics Division
Oak Ridge National Laboratory
Oak Ridge, Tennessee
April 21, 1965
RELEASED MOX AMNO!RCELINT
IN NUCLEAR SCIENCE ABSTRACTS
*Research sponsored by the U.S. Atomic Energy Commission under contract
with the Union Carbide Corporation. '
ORNI - AEC - OFFICIAL
REFRACTORY-ALLOY
NONDESTRUCTIVE TESTING OF SMALL-DIAMETER TUBING
ORNI - AIC - OFFICIAL
K. V. Cook and R. W. McClung
ORML - ACC-OFFICIAL
INTRODUCTION
In the nuclear industry, as in the aerospace industry, tubing intended for
such applications as heat exchangers is being subjected to higher temperatures
and more corrosive environments than in the past. This has led to the develop-
ment of a number of new alloys intended to withstand these rigorous conditions.
However, the use of a "super" alloy would he to no avail if the tube contained
defects, since this could produce just as disastrous & failure as the use of
inadequate alloys. Therefore, to exploit the advantages of the new refractory
metals, it has been necessary to utilize nondestructive testing methods to
assure that the finished product is free of detrimental discontinuities and
will perform in accordance with design expectations. At the Oak Ridge National
Laboratory (ORNL) we have used a number of such tests to evaluate refractory-
metal alloy tubing.aga Of course, the choice of specific tests may vary
according to the character and use of the tube. Those which have been applied
at ORNL include pulsed ultrasonics, eddy currents, penetrants, and radiography
for flaw.detection, and resonance ultrasonics and air gaging for dimensional
measurements.
FLAW DETECTION
'.':,.
..
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Ultrasonics
..
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General Principles
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The use of ultrasonics for flaw detection involves the conversion of an
electrical signal into an ultrasonic pulse or high frequency mechanical vibra-
tion, the transmission of the ultrasound into the specimen, and the analysis
of the pulses which are reflected from or transmitted through the specimen.
When an ultrasonic pulse, traveling through a couplant such as water,
strikes a metal specimen, the sound wave will be refracted at the acoustic
boundary in accordance with Snell's law:
sin ew
sin eg,
sinos
-.
.
.
.
ORNI - AEC - OFFICIAL
where = incident angle of the ultrasonic beam in water,
0= angle of refraction for the longitudinal wave,
Os = angle of refraction for the shear wave,
V = velocity of sound in water,
V, - velocity of the refracted longitudinal wave,
Vs = velocity of the refracted., shear wave.
For conventional tubing inspection for the detection of cracks and other longi-
tudinal discontinuities, the ultrasonic beam is adjusted so that it is incident
upon the tubing at an appropriate angle which allows the refracted sound to
travel around the tube wall in a circumferential direction. If the tube wall
is thick, a simple shear-wave inspection can be performed with the shear wave
following a sawtooth path around the tube wall. If a flaw is present, a
portion of the sound will be reflected and detected. However, for most small-
diameter thin-wall tubing inspections, a more complicated form of wave motion
ORNI - AEC - OFFICIAL
YIRUNO-RIY-THIO
(Lamb waves) is utilized. The tube wall essentially channels the ultrasonic
Lamb waves around it in a manner very similar to a wave guide. Figure 1 is an
attempt to illustrste both shear-wave and Lamb-wave propagation of sound in
tubing. The optimum incident angle required to generate Lamb waves," 18
critical and can vary with the ultrasonic frequency, tubing material, and wall
thickness. In practice the proper incident angle is usually determined empiri-
cally with a reference tube containing discontinuities of known size on both
inner and outer surfaces.
ORNI- AIC - OFFICIAL
Equipment
In general, commercial ultrasonic instrumentation has been used at ORNL
for the application of ultrasonics to tubing inspection for generating,
detecting, and displaying the signals associated with the test. Exceptions
to this have been special fast-response gating and alarm circuits. Figure ?
shows the block diagram of the system used at ORNL for inspecting turing. 3,4
Most of the ultrasonic transaucers have been standard items with active
elements of quartz, lithium sulfate or lead zirconium titanate. The mechanical
equipment is the same as that originally developed at ORNI for the immersed
ultrasonic inspection of tubing. This equipment consists of an immersion tank
and a scanner dolly which holds a search tube and transducer and maintains the
turing in proper alignment during the examination. A motor and gear reducer
assembly rotates the tubing and simultaneously translates the scanner dolly in
a longitudinal direction, accomplishing a helical scan. Figure 3 shows the
dolly used for the conventional inspection Figure 4 provides another view of
the dolly and shows the mechanism for mechanical scanning.
.
.
.
.
Reference Standards
Lithuania!
.
Calibration of equipment to establish test sensitivity is accomplished
using reference standards which contain fabricated discontinuities. Different
methods were studied for the preparation of such standards and we feel that
electrodischarge machining (EDM) is the best for producing reference notches.
The size of these notches varies depending on material specifications with the
smallest required to date being only 1/8 in. long x 0.001 in. deep. Reproduci-
bility of notches is very good. The limitation on accuracy seems to be the
tolerance of +2 u in measuring the depth of the finished notch by optical
microscopy. Figure 5 shows the electrodischarge machine used to fabricate
these notches. A voltage is applied to the electrode arm containing a small
brass cutting shim. A close-up of the electrode arm and shim is shown in Fig. 6.
When the shim is brought close to the tube (which is grounded) an electrical
arc is produced thereby eroding a portion of the tube and a portion of the shim.
By establishing the relationship of tool wear to notch depth for each material,
a calibration is accomplished which can be used for machining notches of pre-
scribed depths. A typical calibration curve for Mo-0.5% Ti is shown in Fig. 7.
Shop
incin
ORNI - AEC - OFFICIAL
Of course, optical microscopy can be directly applied only to outer-diameter
notches. With inner-surface notches this technique is impossible unless the
tube is split. Hence, for inner-surface notches techniques have been developed
for making rubber replicas of the reerence discontinuities and then measuring
them by the differential focusing technique. Successful replications of inner-
surface notches have been made as far as 3 in. from the end of tubes having an
inner diameter as small as 0.230 in. A silicone rubber (RTV-60) is used for
these replicas on both inner- and outer-surface notches. Thinning the rubber
mix with toluene improves its pouring characteristics and allows its use in
areas of poor accessiblity. No 1086 in accuracy has been noted with this
addition. Metallographic sections of both notches and their replicas have
been taken and correlation between the two is excellent. Figure 8 shows in
cross section an approximate center position of a 1/8-in. long, 0.001-in. deep,
0.0025-in. wide outer-surface notch in Inconel tubing. The differential
ORNI - AEC - OISICIAL
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ORNI - AIC - OFFICIAL
OINI -ALC - OINICIAL
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Fig. 1. Propagation of Sound in Tube Wall.
a
ORNI - AEC - OFFICIAL
Fig. 2. Block Diagram of Ultrasonic System for Inspecting Tubing.
.
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WAVE GUIDE ACTION
SHEAR MODE
TUBING
TUBING
SOUND BEAM
SOUND BEAM
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--- TUBING SURFACE
REFLECTION
TUBING SURFACE
REFLECTION-
TIMING AND
REFLECTION SIGNALS
M
TIME
TUBING
ROTATION
001
FLAW
REFLECTION
360°
VIDEO DISPLAY
ROTATIONAL SIGNAL
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DATA POTENTIOMETER
BASIC ULTRASONIC
GENERATOR AND DETECTOR
TUBING ROTATION
B-SCAN DATA PRESENTATION
TRANSMIT-RECEIVE
CRYSTAL
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ORNI - AEC - OFFICIAL
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Fig. 4. Dolly and Scanner Mechanism for Tubing Inspection.
ORNI - AC - OFFICIAL
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ORNL - AEC - OFFICIAL
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Fig. 5.
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Fig. 6. Electrodischarge Machine Electrode Arm and Shim.
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Fig. 8. Cross Section of a 0.001-in. Deep EDM Notch.
Fig. 7. Calibration Curve for Mo~0.5% Ti.
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ORNI - AIC -ORPICIAL
ORNI - ALC - OFFICIAL
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ORNI - AEC - OFFICIAL
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itijisi ve
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IVIJIJIO- 33 V-TRIO
rivol
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focusing technique was used to measure the depth of this notch before sectioning.
The apparent depth as mrasured by this technique was (0.00100 + 0.00008) in. As
is evident from the photomicrograph, the depth was confirmed. Figure 9 is a
cross section of a replica of a machined notch.
O NL-ACC-OFFICIAL
Applications
itijisini
The ultrasonic method has been applied successfully for tice evaluation of
tubes made of a number of alloys in various sizes. The base constituent of the
alloys has included tantalum, columbium, tungsten, molybdenum, zirconium, and
nickel. The sizes have ranged from about 0.250-in. OD X 0.009-in. wall up to
l-in. OD X 0.031-in. wall. By modifying the scanning procedure, the technique
has even been applied to 2-in. OD X 1/4-in. wall refractory-metal tube shells to
assure their quality before fabrication into small-diameter tubing. The smallest
flaws which have been detected and confirmed by metallography are 0.0005-in. deep
inner-surface discontinuities such as shown in Fig. 20. Other typical disconti-
nuities are the inner-surface crack found in 1/2-in. OD X 0.062-in. wall B-66
tubing, the inner-surface cracks found in 1/2-in. OD X 0.062-in. wall D-43
tubing, and the outer-surface crack found in 1/4-in. OD X 0.015-in. wall T-111
tubing shown in Figs. ll, 12, and 13, respectively.
-
Special Techniques
*
-
;
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Although the previously described technique is applicable to most conven-
į tional tubing, special products such as tapered and multilayer (e.g., duplex)
tubing, require specialized techniques. Ultrasonics have been successfully
applied to each of these problems.
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Tapered Tubing. – We were recently faced with the problem of inspecting thin
wall tubing which had a constantly varying diameter. As described previously
for constant wall thickness, there is a critica), optimum angle of sound entry
for proper ultrasonic inspection. Therefore, we had to modify the basic mechan-
ical system to maintain a fixed angle of incidence despite variations in the
.
conventional tubing in proper alignment with the sound beam during the helical
scan. This is accomplished with two face plates containing Teflon bushings
which are machined to fit the inspected tubing and are mounted on either side
of the search tube. For tapered-tübing inspection, the face-plate bushings
are machined to fit the maximum diameter of the tube. The search tube is
adjusted and fixed in a constant position relative to the face plates. This
adjustment is made to obtain optimum response to inner- and outer-surface
longitudinal notches placed near the maximum diameter. Two spring-loaded
V-block devices hold the tubing at a constant point of tangency which coincides.
with the proper incident angle of the sound beam for inspection as the tube is
traversed. The V-blocks are adjustea to obtain optimum response to notches
near the minimum diameter. Thus, the incident angle of the sound beam on the
tube wall does not vary as the diameter changes. Figure 14 is a cross-
sectional drawing showing how the axis of the tube is shifted along a radius
S.
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ORNI - AEC - OFFICIAL
point of tangency. Figure 15 shows a tapered tube passing through face plates
on the modified scanner dolly and the V-block mechanical devices. A universal
joint connection is used for rotating the tubing which is not coaxial with the
chuck. Hence, it is possible with this system to maintain the ultrasonic
inspection setup despite the tapering of the tube. The technique has been
shown to be capable of detecting longitudinal discontinuities with depths
less than 0.001 in. A typical discontinuity detected in 0.009-in. wall Inconel
tapered tubing is shown in Fig. 16. This discontinuity is located in an area
which gave an ultrasonic response approximately equivalent to that from a
0.001-in. deep x 0.0025-in. wide x 1/8-ir.. long EDM notch.
ORNI - AEC - OFFICIAL
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Fig. 10.
Fig. 9.
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Inner-Surface Discontinuities on 0.009-in. Wall Inconel
Cross Section of a Replica of a 0.001-in. Deep EDM Notch.
ORNI - AEC - OFFICIAL
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Fig. 11.
Alloy Tubing:
Inner-Surface Crack in 1/2-in. OD X 0.062-in. Wall B-66
IYIDIO-BY-liit
Fig. 12.
Alloy Tubing.
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Fig. 13.
Tubing.
Outer-Surface Crack in 1/4-in. OD X 0.015-in. Wall T-111 Alloy
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Fig. 14. Tube Cross Sections Showing Constant Incident Angle at Common
Points of Tangency.
23
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ORNI - AEC - OFFICIAL
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ORAL-NIC-OFFICIAL
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Fig. 16.
Inner-Surface Crack in 0.009-in. Wall Tapered Tube.
Multilayer Tubing. - Another special requirement was for the detection of
nonbonding between layers of multilayer tubing. A through-transmission tech-
nique using two piezoelectric crystals was applied to this problem. One of
the transducers served as a transmitter and the other as a receiver. In
practice the transmitting crystal was placed in a small probe which fits irito
the inner diameter of the tubing. The receiver was a collimated transducer
mounted in the scanning dolly of the tube scanning tank. The two crystals
were aligned and fixed relative to each other, the combination moving longi-
tudinally along the tube as it was rotated. Thus, a helical scan was accom-
plished. Figure 17 shows this system with the probe entering the bore of a
tube. If a nonbond exists the amount of sound being transmitted through the
tube wall will be attenuated and can be related to a reference sensitivity.
A flat-bottomed drilled hole was used as a reference for establishing the
inspection sensitivity.
Penetrants
Principles
ORNL - AEC - OSFICIAL
We have found dye penetrants to be a very valuable tool for the evaluatici
of refractory-metal tubing for outer-surface discontinuities. The basic method
consists of applying a highly penetrating liquid containing a dye material to
the surface of the part. A portion of the dye-bearing material will penetrate
surface-connected discontinuities such as cracks, laps, and pinholes. The
liquid is then removed from the surface leaving the entrapped portions in the
flaws. A developer is usually applied to assist the penetrant in returning
to the surface so that it may be detected as an indication of a discontinuity.
ORNI-AIC - OPTICIAL
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layer Tubing.
Fig. 17.
Two-Crystal System for Through-Transmission Evaluation of Multi-
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Materials and Procedure
ORNI - AEC - OFFICIAL
ORNI ATC-irricidil
We prefer to use the post-emulsified fluorescent-penetrant process because
of its greater sensitivity and contrast when compared to other penetrant:
processes (illustrated in Fig. 18). The l'irst step is a thorough cleaning
by degreasing or ultrasonic cleaning to assure that defects are not contami-
nated so that penetrant cannot enter. After removal of cleaning solutions
(usually by warm air drying), the penetrant is applied and allowed to remain
for approximately 30 min. Next an emulsifier is applied for approximately
1 1/2 min before using a forceful spray of warm water to remove the emulsi-
fied penetrant. The emulsifier has poor penetrating qualities so that the
penetrant which has flowed into flaws will not be affected by the application
of emulsifier. The tube is then dried in warm air and a dry powder developer
is app.?.i. ed. After about 15 min the tube is ready to inspect in a darkened
booth with black light illumination. The depth of discontinuities located by
this method are determined by physical removal with fine files or emery paper.
Care is taken to assure that on acceptable tubes the abraded areas are blended
into the surface and that the surface finish corresponds to that of the rest
of the tube.
Auplication
The penetrant method has been successfully applied to a number of refrac-
tory alloy tubes. The most common discontinuities are pinholes and pits, but
other flaws have included laps, folds, scabs, and cracks. One problem which
has been encountered in certain alloys is a smearing of the surface which
probably occurs in the final polishing operation of the tube fabrication.
This smearing can ciose the surface access of cracks and other defects,
barring the entry of the penetrant and thus producing no indication.
Radiography
Principles
Since radiography is a quite widely used method, there is little need to
go into detailed discussion. Basically it consists of transmitting a beam
of x- or gamma-rays through a specimen and recording the intensity variations
on a photographic emulsion (film). Discontinuities which cause an effective
thickness change will be shown as regions of greater exposure (darkening) or
the film.
Equipment and Materials
We have used commercial x-ray equipment, fine-grained industrial x-ray
Im, and standard processing solutions throughout the radiographic program.
The processed films are examined using high intensity viewers. Low-power
magnification is occasionally useful for observation of minute discontinuities.
Application and Results
O?NL - AEC - OFFICIAL
Nocally the tubing is placed directly on the film holder with adjacent
tubes being tangent so that there is mutual shielding and blocking to minimize
the "undercut" from scattered radiation which would degrade the images. For
complete radiographic inspection we have used three exposures at 120° rotational
intervals on each tube section. For samplirg evaluations we occasionally radio-
graph all of the tubing with one view cnly.
OANI - AC - OFFICIAL
will sent times
We have foura radiography to be useful for the detection of inner-surface
pits, gouges, ara extrusion or draw marks. In some materials it could be
useful for the coservation of segregation or inclusions. Although the method
.
4
.
Fig. 28.
Fluorescenti-Fonctrant Teclinique.
Onli-Arc-OINICIAL
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OGNI-AC-OFFICIAL
ORHI-NCC-OFFICI!!!




will find only those cracks which are properly oriented relative to the radi.-
ation beam, it has demonstrated its ability to find such discontinuities.
Eddy Currents
ORHI-AIÇ - OFFICIAL
Principles
In essence the eddy-current cu cod cor.sists of inducing currents into
the metal tube to be inspected by bringing it into the electromagnetic field
of a coil which is being supplied with an alternating current. The coil may
encircie the pert, or be inaced on the surface oi the part in the form of a
probe. Also in the case of tubular shapes, a coil may be wound to fit the
inner diameter. The flow or the induced eddy currents 1s aflected by the
dimensions and electrical properties of the tube and by discontinuities which
may be present in the tube. The variations in the magnitude, phase, and the
distribution of the induced eddy currents will have an effect on the original
field of the coil. All eday-current methods attempt to measure the field
alterations.
Equipent and Applications
We have used commercial instrumentation and test coils as well as special
ORAL designed and fabricated equipment for ecay-current testing of tubing.
Tne coil designs have includcd inner-diameter "bobbin" coils, encircling coils,
and probe coils. Of these the encircling coil has been preferred due to the
relative ease of mechanical handling of the tube, and the faster inspection
speed despite a sensitivity slightly lower than that possible with probe coils.
The optimun coil design and test frequency are affected by the tube diameter,
wall thickness, and electrical conductivity. For most practical techniques a
single inspection is made for both inner- and outer-surface discontinuities.
Since the test is normally more sensitive to those i iscontinuities on the sur-
face nearest the coil, we have used reference tubes containing both inner- and
outer-surface discontinuities of known size to establish optimun test condi-
tions and assure that a complete inspection was being performed. crur reference
discontinuities have been electrodischarge-machined notches similar or the
same as those used for ultrasonic calibration.
Results
In general good correlation has been observed between eddy-current test
indicacions and destructive metallojraphic examination. When using the
encircüing coil to detect both inner- and outer-surface Flavs a practical
sensitivi:y limit seems to be for flaws with depths about 20% of the wall
thickness aitz.ough better results can be obtained in certain cases. When the
wall thickness-to-dieter ratio becomes so larse that reasonable response
cannot be obtained iron flaws on the oppočite surface, it may be desirable
to perform separate inspections on each surface and inuch better sensitivities
can be observed. On occasion with very thin wall tubing (i.e., 0.020 in. and
less), we aave encountered excessive spurious signals due to small localized
dimensional variatioris when using an encirclins coil system. Many of these
indicacions can be avoided through the use of a probe coil system.
DIMENSIONAL GAGING
Wall Thickness by Ultrasonics
C:HlAir-OFFICIAL
Princones
no do mundon
A resonant ultrasonic technique is used to monitor tubing wall thickness
variations. This method requires continuous ultrasonic waves to be transmitted
ORHI-HEC-OFFICIAL
through a coupiant into a metal specimen. The frequency (and thus the wave
lengsta) of these waves is varicd until a standing wave condition occurs which
causes resonance of the specimer.. Standing waves (illustrated in Fig. 19)
occur when the sample thickness (t) is exactly equal to an integral nunber (r.)
of half wavelengths (a) of icitudinal waves propagated perpendicularly through
the specimen, or
t = ma .
ORHI - ABC-OITICIEL
Since
wave length
=
velocity
Freguency
/
by substitution
t =
.
Hence, for a tube the wall thickness may be determined from a knowledge of the
velocity of sound in the material and or ve resonant Irequency (oundamental
or harmonic). Also any wall thickness variations will cause a proportional
change in the resonant frequency.
Equipment
Commercial equipment is used to display resonant conditions. The basic
instrument automatically sweeps the ultrasonic frequency through a preden
termined band and displays the conditions or resonance as vertical "pips" on
the screen of a cathode ray tube (CRT). The face of the CRT can then be cal-
ibrated to read directly in thickness over spec::I'ic ranges. The transaucers
used in conjunction with this equipment can be either of the contact or im-
mersion type. However, if the immersion riechodº is used some mechanical
device similar to the one shown in Fig. 20 is necessary to allow precision
scanning of the tubing. This device enables one to change the water path
distance from the crystal to the tube, to adjust the incident sound beam
perpendicular to the top or the tube, and to maintain these conditions, via
the Teflon-covered V-block, as it is scanned along the rotating tube.
Applications and Results
In practice, calibration is established on a tube from the lot to be
monitored or gaged. For best accuracy in calibration, it is desirable to
use a tube with the greatest variation in wall thickness. Exacü values of
wall thickness are measured at a tube end wich a device such as tubing
micrometer and the measured thicknesses are reproduced by the ultrasonic
equipmeat during the dynamic calibration. With or equipment we can read
othicknesses for steel over a range from about 0.008 to 0.500 in. The
demonstrated accuracy for tubing measurement has been about 7%. Both contact
and immersion resonance methods have been used to gage wall thickness in
each tube from end to end, and both maximum and minimum values are normally
reported.
Other Dimensional Measurements
Olill-MIC-OFFICIAL
OEMI-AUG-OFFICIAL
Doay Currents
Fady-current techniques are also used for measuring the inner diameters of
tubing for maximum and minimun values. The measurements themselves are essen-
tially spacing measurements,? using a spririg-loadeä probe. Figure 21 shows a
typical probe design for measuring the bore of small-diameter tubing.
OAM(-All-OFFICIAL
OKMI - ACC-OUFICIEL
.
2
21
Fig. 19. Ultrasonic Resonance Technique.
DAIL-ACC-01CIAL
ORNI -A&C-OINICIAL
Lu
..unc.emain
ie
i
'wind
o
.
BYLA OYUNU
XINA
OHTONIC-OrrICIAL
Ofri-NIC-OISICIAL
ORNL-LR-DWG 47487
one
Now
O w
OX
WAVELENGTH
FUNDAMENTAL
FREQUENCY
T= 2 VAVELENGTHS
9th HARMONIC
T=-
-
-------.
.
.
TRANSDUCER
OR:ML - AEC - OSSIC!.(



OPNI - AEC - OFFICIAL
-
I,
-
.
K
.
Fig. 20.
29
Tubing Scanner for Immersion Resonance Testing.
ORNI - AC-OFFICIAL
O*NI-MIC-tificial
OPNI - HEC - OFFICIAL
Chill - AEC - Ori,CIAL
OFM - AEC - OFFICIAL
OEMI-hil-orliciul
anitasimamistooli....main
-..
Fig. 21.
Tubing Inner-Diameter G
.
ORNI - AEC - OFFICIAL
OXHL-ACC-Ornicial
1711310- 33V - 13:20
17101330 - 13Y- INDO
TY131330 -
3 V-1:20
7101310- 33 V - IN8O
UNCLASSIFIED
ORNL-LR-D10 57396
-ENCIRCLING COIL
FERROMAGN TIC
FEELLR-
bomo
1
ZZZ
Y-SORING
NON-CONDUCTOR-
ORHI-NCC-OFFICIAL
OFH-MIC-OUSICIEL
sh
pu
no
ot
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al
3 caput

Longitudinal or circunferential movement of the probe through a tube with inner-
diameter variations will cause lateral movement of the diametrically oriented
spring-loaded Ierromagnetic feeler within the solenoid coil. These feeler
variations are reflected as impedance changes in the coil. Appropriate instru-
mentation for monis ng these impedance changes can be calibrated with a
micrometer or any other precision mechanical device. Thus, a direct meter or
recorder indication can be obtained for these variations.
ORNL-ACC-OFFICIAL
Mechanical Measurements
Air gaging techniques are used to examine inner diameters of tubing for
makinum and minimum values. In addition micrometers and calipers are used
'or occasional measurements of ovality and wall thickness in accessible areas.
CONCLUSIONS
The various techniques and methods which have been discussed represent a
general program used to examine and evaluate small-diameter tubing for nuclear
applications. The program as outlined can be varied according to the service
requirements of the tubing. Some of the methods are identical to those used in
other industries; others may be unique to the nuclear field. From this dis-
cussion, it is evident that more than one nordestructive testing technique is
neeaed to assure the integrity of high quality tubing and similar programs
should be used for selecting such tubing for any industry.
-
RIFERENCES
-
1. K. V. Cook and R. W. McClung, "Horidestructive Evaluation of D-43 Alloy
Tubing by Oak Ridge National Laboratory," ORNL-TN-843, June 1964.
2. K. V. Cook and R. W. McClung, "Nondestructive Evaluation of T-111 and
B-66 Alloy Tubing," ORNL-IM-990, February 1965.
3. D. C. Worlton, J. Soc. rondestructive Testing 15(4) 218--22 (1957).
4. H. Lamb, Proc. Roy. Soc. (Iondon) 93(4) 114-28 (1916–17).
:
5.
2. B. Oliver, R. 1. cclung, J. K. White, "Immersed Ultrasonic Inspection
of Pipe and Tubins," ORNL-2254, February 1957.
......-
6. R. V. Harris, "Im.ersion Resonance Testing," paper preserved at Society for
rondestructive Testing, 20.3t National Convention, Detroic. Michigan,
October 23–27, 1961; published in Ultrasonic News, Brarson Instruments, Inc.,
Spring 1962.
..-.--.--.-
7.
C. V. Doda, Microtecnic, Ist part 18(5), 286-89 (Oct. 1964); 2nd part
18(6), 369–7. (Dec. 1964).
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OFN! - AEC - OPTICIAL
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Originiitti

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mano
IT:
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DATE FILMED
10/ 15/65
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