ASTM E114-95
(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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 114 – 95 An American National Standard
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 Magnetic Particle, Radiographic and Ultrasonic)
1.1 This practice covers ultrasonic examination of materi-
3. Terminology
als by the pulse-echo method using straight-beam longitudinal
3.1 Refer to Terminology E 1316 for definitions of terms
waves introduced by direct contact of the search unit with the
used in this practice.
material being examined.
1.2 This practice shall be applicable to development of an
4. Basis of Application
examination procedure agreed upon by the users of the
4.1 Purchaser-Supplier Agreements:
document.
The following items require agreement between the using
1.3 The values stated in inch-pound units are to be regarded
parties for this practice to be used effectively:
as the standard.
4.1.1 Qualification of Nondestructive Testing Agencies—
1.4 This standard does not purport to address all of the
Agreement is required as to whether the nondestructive testing
safety concerns, if any, associated with its use. It is the
agency, as defined in Practice E 543 must be formally evalu-
responsibility of the user of this standard to establish appro-
ated and qualified to perform the examination. If such evalu-
priate safety and health practices and determine the applica-
ation and qualification is specified, a documented procedure
bility of regulatory limitations prior to use.
such as Practice E 543 shall be used as the basis for evaluation.
2. Referenced Documents 4.1.2 Personnel Qualification—Nondestructive testing
(NDT) personnel shall be qualified in accordance with a
2.1 ASTM Standards:
nationally recognized NDT personnel qualification practice or
E 317 Practice for Evaluating Performance Characteristics
standard such as ANSI/ASNT-CP-189, SNT-TC-1A, MIL-
of Ultrasonic Pulse-Echo Testing Systems Without the Use
STD-410, or a similar document. The practice or standard used
of Electronic Measurement Instruments
and its applicable revision shall be specified in the contractual
E 543 Practice for Evaluating Agencies that Perform Non-
agreement between the using parties.
destructive Testing
3 4.1.3 Extent of Examination—The extent of the examina-
E 1316 Terminology for Nondestructive Examinations
tion shall be determined by agreement of the using parties.
2.2 ASNT Standards:
4.1.4 Time of Examination—The time of examination shall
SNT-TC-1A Recommended Practice for Personnel Qualifi-
be determined by agreement of the using parties.
cation and Certification in Nondestructive Testing
4.1.5 Interpretation Criteria—The criteria by which the
ANSI/ASNT CP-189 ASNT Standard for Qualification and
4 ultrasonic signals and part acceptability will be evaluated and
Certification of Nondestructive Testing Personnel
shall be determined by agreement of the using parties.
2.3 Military Standard:
MIL-STD-410 Nondestructive Testing Personnel Qualifica-
5. Significance and Use
tion and Certification (Eddy Current, Liquid Penetrant,
5.1 A series of electrical pulses is applied to a piezoelectric
element (transducer) which converts these pulses to mechani-
cal energy in the form of pulsed waves at a nominal frequency.
This transducer is mounted in a holder so it can transmit the
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.06 on
waves into the material through a suitable wear surface and
Ultrasonic Method.
couplant. The assembly of transducer, holder, wearface, and
Current edition approved May 15, 1995. Published July 1995. Originally
electrical connnector comprise the search unit.
published as E 114 – 55 T. Last previous edition E 114 – 90.
For ASME Boiler and Pressure Vessel Code applications see related Practice 5.2 Pulsed energy is transmitted into materials, travels in a
SE-114 in Section II of that Code.
Annual Book of ASTM Standards, Vol 03.03.
Available from American Society for Nondestructive Testing, 1711 Arlingate 5
Available from the Superintendent of Documents, U.S. Government Printing
Plaza, P.O. Box 28518, Columbus, OH 43228-0518.
Office, Washington, DC 20402.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E114
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—A couplant, usually a liquid or semi-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 calibration should
ties. By adjustment of the sweep (range) controls, this display be used for the examination. During the performance of a
can be expanded or contracted to obtain a designated relation 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, heat
5.3 Types of information that may be obtained from the
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 coupling will usually provide a better examination. In this case,
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
couplant. Liquid flowing through the search unit fills the gap.
6. Apparatus
The flowing liquid provides the coupling path and has the
6.1 Complete ultrasonic apparatus shall include the follow-
additional advantage of cooling the search unit if the exami-
ing:
nation surface is hot.
6.1.1 Instrumentation—The ultrasonic instrument shall be
6.1.3.4 An alternative means of direct contact coupling is
capable of generating, receiving, and amplifying high-
frequency electrical pulses at such frequencies and energy
TABLE 1 Suggested Viscosities—Oil Couplants
levels required to perform a meaningful examination and to
NOTE 1—The table is a guide only and is not meant to exclude the use
provide a suitable readout.
of a particular couplant that is found to work satisfactorily on a particular
6.1.2 Search Units—The ultrasonic search units shall be
surface.
capable of transmitting and receiving ultrasound in the material
Approximate Surface Roughness Average Equivalent Couplant Vis-
at the required frequencies and energy levels necessary for
(Ra), μin. (μm) cosity, Weight Motor Oil
discontinuity detection. Typical search unit sizes usually range
5–100 (0.1–2.5) SAE 10
1 1
from ⁄8 in. (3.2 mm) in diameter to 1 ⁄8 in. (28.6 mm) in 50–200 (1.3–5.1) SAE 20
100–400 (2.5–10.2) SAE 30
diameter with both smaller and larger sizes available for
250–700 (6.4–17.8) SAE 40
specific applications. Search units may be fitted with special
Over 700 (18–) cup grease
shoes for appropriate applications. Special search units encom-
E114
provided by the wheel search unit. The search unit is mounted equipment, geometry and material type, information desired, 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 calibrated 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 For bond/unbond (fusion/lack of fusion) 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 calibration. item being examined containing areas representing both
These artificial reflectors may be in the form of flat-bottom bonded (fused) and unbonded (lack of fusion) conditions, if
holes, side-drilled holes, or slots. An alternate method of geometry and material permit.
fabricating a reference standard may be the introduction of 7.7 Calibration with respect to reference standards should
known discontinuities during the fabrication process of a be periodically checked to ensure that the ultrasonic system
production item or other convenient configuration. The surface calibration is not changing. As a minimum, the calibration shall
finish of the reference standard should be similar to the surface be checked each time there is a change of operators, when
finish of the production item (or corrected; see 7.3). The search units are changed, when new batteries are installed,
reference standard material and the production material should when equipment operating from one power source is changed
be acoustically similar (in velocity and attenuation). The to another power source, or when improper operation is
reference standard selected shall be used by the examiner as the suspected.
basis for signal comparisons.
8. Procedure
7. Calibration of Equipment
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
with Practice E 317 or another procedure approved by the users 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, calibrate the system in accordance characteristics may also cause rapid shifts in apparent depth as
with the product specification. the search unit approaches or moves away from the low
7.3 Where the surface finishes of the reference standard and amplitude indication. Another effect of these reflectors is the
the production item do not match, or where there is an acoustic loss of b
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