ASTM E114-95(2001)
(Practice)Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by the Contact Method
Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by the Contact Method
SCOPE
1.1 This practice covers ultrasonic examination of materials by the pulse-echo method using straight-beam longitudinal waves introduced by direct contact of the search unit with the material being examined.
1.2 This practice shall be applicable to development of an examination procedure agreed upon by the users of the document.
1.3 The values stated in inch-pound units are to be regarded as the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E114–95 (Reapproved 2001)
Standard Practice for
Ultrasonic Pulse-Echo Straight-Beam Examination by the
Contact Method
This standard is issued under the fixed designation E 114; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope NAS-410 NASCertification&QualificationofNondestruc-
2 tive Test Personnel
1.1 This practice covers ultrasonic examination of materi-
als by the pulse-echo method using straight-beam longitudinal
3. Terminology
waves introduced by direct contact of the search unit with the
3.1 Refer to Terminology E 1316 for definitions of terms
material being examined.
used in this practice.
1.2 This practice shall be applicable to development of an
examination procedure agreed upon by the users of the
4. Basis of Application
document.
4.1 Purchaser-Supplier Agreements:
1.3 The values stated in inch-pound units are to be regarded
The following items require agreement between the using
as the standard.
parties for this practice to be used effectively:
1.4 This standard does not purport to address all of the
4.1.1 Qualification of Nondestructive Testing Agencies—
safety concerns, if any, associated with its use. It is the
Agreement is required as to whether the nondestructive testing
responsibility of the user of this standard to establish appro-
agency, as defined in Practice E 543 must be formally evalu-
priate safety and health practices and determine the applica-
ated and qualified to perform the examination. If such evalu-
bility of regulatory limitations prior to use.
ation and qualification is specified, a documented procedure
2. Referenced Documents such as Practice E 543 shall be used as the basis for evaluation.
4.1.2 Personnel Qualification—Nondestructive testing
2.1 ASTM Standards:
(NDT) personnel shall be qualified in accordance with a
E 317 Practice for Evaluating Performance Characteristics
nationally recognized NDT personnel qualification practice or
of Ultrasonic Pulse-Echo Examination Systems Without
3 standardsuchasANSI/ASNT-CP-189,SNT-TC-1A,NAS-410,
the Use of Electronic Measurement Instruments
or a similar document. The practice or standard used and its
E 543 Practice for Agencies Performing Nondestructive
3 applicable revision shall be specified in the contractual agree-
Testing
3 ment between the using parties.
E 1316 Terminology for Nondestructive Examinations
4.1.3 Extent of Examination—The extent of the examina-
2.2 ASNT Standards:
tion shall be determined by agreement of the using parties.
SNT-TC-1A Recommended Practice for Personnel Qualifi-
4 4.1.4 Time of Examination—The time of examination shall
cation and Certification in Nondestructive Testing
be determined by agreement of the using parties.
ANSI/ASNT CP-189 ASNT Standard for Qualification and
4 4.1.5 Interpretation Criteria—The criteria by which the
Certification of Nondestructive Testing Personnel
ultrasonic signals and part acceptability will be evaluated and
2.3 Other Documents:
shall be determined by agreement of the using parties.
5. Significance and Use
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.06 on 5.1 A series of electrical pulses is applied to a piezoelectric
Ultrasonic Method.
element (transducer) which converts these pulses to mechani-
Current edition approved May 15, 1995. Published July 1995. Originally
cal energy in the form of pulsed waves at a nominal frequency.
published as E 114 – 55 T. Last previous edition E 114 – 90.
This transducer is mounted in a holder so it can transmit the
For ASME Boiler and Pressure Vessel Code applications see related Practice
SE-114 in Section II of that Code.
Annual Book of ASTM Standards, Vol 03.03.
4 5
Available from American Society for Nondestructive Testing, 1711 Arlingate Available fromAerospace IndustriesAssociation ofAmerica, 1250 Eye Street,
Plaza, P.O. Box 28518, Columbus, OH 43228-0518. N.W., Suite 1200, Washington, D.C. 20005-3924 .
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E114–95 (2001)
1 1
waves into the material through a suitable wear surface and from ⁄8 in. (3.2 mm) in diameter to 1 ⁄8 in. (28.6 mm) in
couplant. The assembly of transducer, holder, wearface, and diameter with both smaller and larger sizes available for
electrical connnector comprise the search unit. specific applications. Search units may be fitted with special
5.2 Pulsed energy is transmitted into materials, travels in a shoes for appropriate applications. Special search units encom-
direction normal to the contacted surface, and is reflected back passing both a transmitter and a receiver as separate piezoelec-
to the search unit by discontinuity or boundary interfaces tric elements can be utilized to provide some degree of
which are parallel or near parallel to the contacted surface. improved resolution near the examination surface.
These echoes return to the search unit, where they are 6.1.3 Couplant—Acouplant,usuallyaliquidorsemi-liquid,
converted from mechanical to electrical energy and are ampli- is required between the face of the search unit and the
fied by a receiver. The amplified echoes (signals) are usually examination surface to permit or improve the transmittance of
presented in an A-scan display, such that the entire round trip ultrasound from the search unit into the material under test.
of pulsed energy within the resolution of the system may be Typical couplants include water, cellulose gel, oil, and grease.
indicated along the horizontal base line of the display by Corrosion inhibitors or wetting agents or both may be used.
vertical deflections corresponding to echo amplitudes from Couplants must be selected that are not detrimental to the
each interface, including those from intervening discontinui- product or the process. The couplant used in standardization
ties. By adjustment of the sweep (range) controls, this display should be used for the examination. During the performance of
can be expanded or contracted to obtain a designated relation a contact ultrasonic examination, the couplant layer between
between the displayed signals and the material reflectors from search unit and examination material must be maintained such
which the signal originates. Thus a scaled distance to a that the contact area is held constant while maintaining
discontinuity and its displayed signal becomes a true relation- adequate couplant thickness. Lack of couplant reducing the
ship. By comparison of the displayed discontinuity signal effective contact area or excess couplant thickness will reduce
amplitudes to those from a reference standard, both location the amount of energy transferred between the search unit and
and estimated discontinuity size may be determined. Discon- the examination piece. These couplant variations in turn result
tinuities having dimensions exceeding the size of the sound in examination sensitivity variations.
beam can also be estimated by determining the amount of 6.1.3.1 The couplant should be selected so that its viscosity
movement of a search unit over the examination surface where is appropriate for the surface finish of the material to be
a discontinuity signal is maintained. examined. The examination of rough surfaces generally re-
quires a high-viscosity couplant. The temperature of the
NOTE 1—When determining the sizes of discontinuities by either of
material’s surface can change the couplant’s viscosity. As an
these two practices, only the area of the discontinuity which reflects
example, in the case of oil and greases, see Table 1.
energy to the search unit is determined.
6.1.3.2 At elevated temperatures as conditions warrant,
5.3 Types of information that may be obtained from the
heat-resistant coupling materials such as silicone oils, gels, or
pulsed-echo straight-beam practice are as follows:
greases should be used. Further, intermittent contact of the
5.3.1 Apparent discontinuity size (Note 2) by comparison of
search unit with the surface or auxiliary cooling of the search
the signal amplitudes from the test piece to the amplitudes
unit may be necessary to avoid temperature changes that affect
obtained from a reference standard.
the ultrasonic wave characteristics of the search unit.At higher
5.3.2 Depth location of discontinuities by calibrating the
temperatures, certain couplants based on inorganic salts or
horizontal scale of the A-scan display.
thermoplastic organic materials, high-temperature delay mate-
5.3.3 Material properties as indicated by the relative sound
rials, and search units that are not damaged by high tempera-
attenuation or velocity changes of compared items.
tures may be required.
5.3.4 The extent of bond and unbond (or fusion and lack of
6.1.3.3 Where constant coupling over large areas is needed,
fusion) between two ultrasonic conducting materials if geom-
as in automated examination, or where severe changes in
etry and materials permit.
surface roughness are found, other couplants such as liquid gap
NOTE 2—The term “apparent” is emphasized since true size depends on couplingwillusuallyprovideabetterexamination.Inthiscase,
orientation, composition, and geometry of the discontinuity and equip-
the search unit does not contact the examination surface but is
ment limitations.
separated by a distance of about 0.2 in. (0.5 mm) filled with
6. Apparatus
6.1 Complete ultrasonic apparatus shall include the follow-
TABLE 1 Suggested Viscosities—Oil Couplants
ing:
NOTE 1—The table is a guide only and is not meant to exclude the use
6.1.1 Instrumentation—The ultrasonic instrument shall be
of a particular couplant that is found to work satisfactorily on a particular
capable of generating, receiving, and amplifying high-
surface.
frequency electrical pulses at such frequencies and energy
Approximate Surface Roughness Average Equivalent Couplant Vis-
levels required to perform a meaningful examination and to
(Ra), µin. (µm) cosity, Weight Motor Oil
provide a suitable readout.
5–100 (0.1–2.5) SAE 10
6.1.2 Search Units—The ultrasonic search units shall be 50–200 (1.3–5.1) SAE 20
100–400 (2.5–10.2) SAE 30
capableoftransmittingandreceivingultrasoundinthematerial
250–700 (6.4–17.8) SAE 40
at the required frequencies and energy levels necessary for
Over 700 (18–) cup grease
discontinuity detection. Typical search unit sizes usually range
E114–95 (2001)
couplant. Liquid flowing through the search unit fills the gap. reflectors. For optimum examination performance, compensa-
The flowing liquid provides the coupling path and has the tions should be made for both near and far-field effects.
additional advantage of cooling the search unit if the exami- 7.5 Unless otherwise specified, the initial pulse and at least
nation surface is hot. one back reflection shall appear on the A-scan display while
examining for discontinuities in materials having parallel
6.1.3.4 An alternative means of direct contact coupling is
surfaces. The total number of back reflections depends upon
provided by the wheel search unit. The search unit is mounted
equipment,geometryandmaterialtype,informationdesired,or
at the required angle to a stationary axle about which rotates a
operator preference. Reduction of the back reflection during
liquid-filled flexible tire. A minimum amount of couplant
scanning is indicative of increased attenuation or sound scat-
provides ultrasonic transmission into the examination surface
tering discontinuities provided that front and back surface
since the elastic tire material is in rolling contact and conforms
roughness and parallelism of the production piece are approxi-
closely to the surface.
mately the same as that of the standard. For non-parallel
6.1.4 Reference Standards—The production item itself may
surfaces, the time trace of the display shall be standardized by
be an adequate standard using the height of the back wall echo
using standards that include the maximum thickness of the
for reference. For more quantitative information, machined
production item being examined.
artificial reflectors (discontinuities) or charts representing
7.6 Forbond/unbond(fusion/lackoffusion)examinations,a
distance-amplitude relationships of known reflector sizes for a
reference standard should be used similar to the production
particular search unit and material may be used for standard-
item being examined containing areas representing both
ization. These artificial reflectors may be in the form of
bonded (fused) and unbonded (lack of fusion) conditions, if
flat-bottom holes, side-drilled holes, or slots. An alternate
geometry and material permit.
method of fabricating a reference standard may be the intro-
7.7 Standardization with respect to reference standards
duction of known discontinuities during the fabrication process
should be periodically checked to ensure that the ultrasonic
of a production item or other convenient configuration. The
system standardization is not changing. As a minimum, the
surface finish of the reference standard should be similar to the
standardization shall be checked each time there is a change of
surface finish of the production item (or corrected; see 7.3).
operators, when search units are changed, when new batteries
The reference standard material and the production material
are installed, when equipment operating from one power
should be acoustically similar (in velocity and attenuation).
source is changed to another power source, or when improper
The reference standard selected shall be used by the examiner
operation is suspected.
as the basis for signal comparisons.
8. Procedure
7. Standardization of Apparatus
8.1 When ultrasonic examinations are performed for the
7.1 If quantitative information is to be obtained, vertical or
detection or sizing of discontinuities, or both, reflectors not
horizontal linearity or both should be checked in accordance
perpendicular to the ultrasonic beam may be detected at
withPracticeE 317oranotherprocedureapprovedbytheusers
reduced amplitudes, with a distorted envelope depending upon
of the document. An acceptable linearity performance may be
the reflector area, whether it is curved or planar, whether it is
agreed upon by the users of the document.
smooth or rough, perhaps with reflecting facets. Reflector
7.2 Prior to examination, standardize the system in accor-
characteristics may also cause rapid shifts in apparent depth as
dance w
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