ASTM E797-95(2001)

Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method

SCOPE
1.1 This practice provides guidelines for measuring the thickness of materials using the contact pulse-echo method at temperatures not to exceed 200oF (93oC).
1.2 This practice is applicable to any material in which ultrasonic waves will propagate at a constant velocity throughout the part, and from which back reflections can be obtained and resolved.
1.3 The values stated in either inch-pound or SI units are to be regarded as the standard. The values given in parentheses are for information only.
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

• Status: Historical
• Publication Date: 31-Dec-2000
• ICS: 17.040.20 - Properties of surfaces
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.06 - Ultrasonic Method

Relations

• Replaces: ASTM E797-95 - Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method
• Effective Date: 01-Jan-2001
• Replaced By: ASTM E797-05 - Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method
• Effective Date: 01-Dec-2005
• Referred By: ASTM E1816-18(2022) - Standard Practice for Measuring thickness by Pulse-Echo Electromagnetic Acoustic Transducer (EMAT) Methods
• Effective Date: 01-Jan-2001
• Referred By: ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
• Effective Date: 01-Jan-2001
• Referred By: ASTM F1743-22 - Standard Practice for Rehabilitation of Existing Pipelines and Conduits by Pulled-in-Place Installation of Cured-in-Place Thermosetting Resin Pipe (CIPP)
• Effective Date: 01-Jan-2001
• Referred By: ASTM E494-20 - Standard Practice for Measuring Ultrasonic Velocity in Materials by Comparative Pulse-Echo Method
• Effective Date: 01-Jan-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E797–95 (Reapproved 2001)
Standard Practice for
Measuring Thickness by Manual Ultrasonic Pulse-Echo
1
Contact Method
This standard is issued under the fixed designation E 797; 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.
1. Scope 4. Summary of Practice
2
1.1 This practice provides guidelines for measuring the 4.1 Thickness (T), when measured by the pulse-echo ultra-
thickness of materials using the contact pulse-echo method at sonic method, is a product of the velocity of sound in the
temperatures not to exceed 200°F (93°C). material and one half the transit time (round trip) through the
1.2 This practice is applicable to any material in which material.
ultrasonic waves will propagate at a constant velocity through-
Vt
T 5
out the part, and from which back reflections can be obtained
2
and resolved.
where:
1.3 The values stated in either inch-pound or SI units are to
T = thickness,
be regarded as the standard. The values given in parentheses
V = velocity, and
are for information only.
t = transit time.
1.4 This standard does not purport to address all of the
4.2 The pulse-echo ultrasonic instrument measures the tran-
safety concerns, if any, associated with its use. It is the
sit time of the ultrasonic pulse through the part.
responsibility of the user of this standard to establish appro-
4.3 The velocity in the material being examined is a
priate safety and health practices and determine the applica-
function of the physical properties of the material. It is usually
bility of regulatory limitations prior to use.
assumed to be a constant for a given class of materials. Its
approximate value can be obtained fromTable X3.1 in Practice
2. Referenced Documents
E 494 or from the Nondestructive Testing Handbook,oritcan
2.1 ASTM Standards:
be determined empirically.
E 317 Practice for Evaluating Performance Characteristics
4.4 One or more reference blocks are required having
of Ultrasonic Pulse-Echo Examination Systems Without
3 known velocity, or of the same material to be examined, and
the Use of Electronic Measurement Instruments
having thicknesses accurately measured and in the range of
E 494 Practice for Measuring Ultrasonic Velocity in Mate-
3 thicknesses to be measured. It is generally desirable that the
rials
3
thicknesses be “round numbers” rather than miscellaneous odd
E 1316 Terminology for Nondestructive Examinations
values. One block should have a thickness value near the
2.2 ASNT Document:
4
maximum of the range of interest and another block near the
Nondestructive Testing Handbook, 2nd Edition, Vol 7
minimum thickness.
3. Terminology
4.5 The display element (CRT (cathode ray tube), meter, or
digital display) of the instrument must be adjusted to present
3.1 Definitions—For definitions of terms used in this
convenient values of thickness dependent on the range being
practice, refer to Terminology E 1316.
used.Thecontrolforthisfunctionmayhavedifferentnameson
different instruments, including range, sweep, material stan-
1
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
dardize,or velocity.
structive Testing and is the direct responsibility of Subcommittee E07.06 on
4.6 The timing circuits in different instruments use various
Ultrasonic Testing Procedure.
conversion schemes. A common method is the so-called
Current edition approved Dec. 10, 1995. Published February 1996. Originally
time/analog conversion in which the time measured by the
published as E 797 – 81. Last previous edition E 797 – 94.
2
For ASME Boiler and Pressure Vessel Code applications, see related Practice
instrument is converted into a proportional dc voltage which is
SE-797 in Section II of that Code.
then applied to the readout device. Another technique uses a
3
Annual Book of ASTM Standards, Vol 03.03.
4
veryhigh-frequencyoscillatorthatismodulatedorgatedbythe
Available from the American Society for Nondestructive Testing, 1711 Arlin-
gate Plaza, Columbus, OH 43228. appropriate echo indications, the output being used either
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

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E797–95 (2001)
NOTE 1—Slope of velocity conversion line is approximately that of steel.
FIG. 1 Transit Time/Thickness Relationship
directlytosuitabledigitalreadoutsorconvertedtoavoltagefor 6.1.1 Flaw detectors with CRT readouts display time/
other presentation. A relationship of transit time versus thick- amplitude information in an A-scan presentation. Thickness
ness is shown graphically in Fig.
...