ASTM E1901-97

Standard Guide for Detection and Evaluation of Discontinuities by Contact Pulse-Echo Straight-Beam Ultrasonic Methods

SCOPE
1.1. This guide covers procedures for the contact ultrasonic examination of bulk materials or parts by transmitting pulsed ultrasonic waves into the material and observing the indications of reflected waves. This guide covers only examinations in which one search unit is used as both transmitter and receiver (pulse-echo). This guide includes general requirements and procedures that may be used for detecting discontinuities, locating depth and distance from a point of reference and for making a relative or approximate evaluation of the size of discontinuities as compared to a reference standard.
1.2 This guide complements Practice E114 by providing more detailed procedures for the selection and calibration of the inspection system and for evaluation of the indications obtained.  
1.3 The values stated in inch-pound units are to be regarded as the standard. The SI units given in parentheses are for information only.  
1.4 This guide 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 guide to establish the appropriate safety and health practices and detemine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Aug-1997
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.06 - Ultrasonic Method

Relations

• Replaced By: ASTM E1901-97(2003) - Standard Guide for Detection and Evaluation of Discontinuities by Contact Pulse-Echo Straight-Beam Ultrasonic Methods
• Effective Date: 10-Jul-2003
• Referred By: ASTM E3370-23 - Standard Practice for Matrix Array Ultrasonic Testing of Composites, Sandwich Core Constructions, and Metals
• Effective Date: 10-Aug-1997
• Referred By: ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
• Effective Date: 10-Aug-1997
• Referred By: ASTM E2533-21 - Standard Guide for Nondestructive Examination of Polymer Matrix Composites Used in Aerospace Applications
• Effective Date: 10-Aug-1997
• Referred By: ASTM E3166-20e1 - Standard Guide for Nondestructive Examination of Metal Additively Manufactured Aerospace Parts After Build
• Effective Date: 10-Aug-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1901 – 97
Standard Guide for
Detection and Evaluation of Discontinuities by Contact
Pulse-Echo Straight-Beam Ultrasonic Methods
This standard is issued under the fixed designation E 1901; 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 E 1158 Guide for Material Selection and Fabrication of
Reference Blocks for the Pulsed Longitudinal Wave Ultra-
1.1 This guide covers procedures for the contact ultrasonic
sonic Examinations of Metal and Metal Alloy Production
examination of bulk materials or parts by transmitting pulsed
Materials
ultrasonic waves into the material and observing the indica-
E 1316 Terminology for Nondestructive Examinations
tions of reflected waves. This guide covers only examinations
2.2 ASNT Standard:
in which one search unit is used as both transmitter and
SNT-TC-1A Recommended Practice for Personnel Qualifi-
receiver (pulse-echo). This guide includes general require-
cation and Certification in Nondestructive Testing Person-
ments and procedures that may be used for detecting discon-
nel
tinuities, locating depth and distance from a point of reference
2.3 ANSI/ASNT Standard:
and for making a relative or approximate evaluation of the size
CP-189 ASNT Standard for Qualification and Certification
of discontinuities as compared to a reference standard.
of Nondestructive Testing Personnel
1.2 This guide complements Practice E 114 by providing
2.4 Military Standard:
more detailed procedures for the selection and calibration of
MIL-STD-410 Nondestructive Testing Personnel Qualifica-
the inspection system and for evaluation of the indications
tion and Certification
obtained.
1.3 The values stated in inch-pound units are to be regarded
3. Terminology
as the standard. The SI units given in parentheses are for
3.1 Definitions—For definitions of terms used in this guide,
information only.
see Terminology E 1316.
1.4 This guide does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
4. Basis for Application
of the user of this guide to establish the appropriate safety and
4.1 Contractual Agreement—The using parties shall agree
health practices and determine the applicability of regulatory
on the applicable procedural requirements, as listed herein,
limitations prior to use.
prior to the examination of any material.
4.1.1 Materials, sizes, and shapes examined,
2. Referenced Documents
4.1.2 Stage of manufacture when examined (time of test),
2.1 ASTM Standards:
4.1.3 Surface finish requirements,
E 114 Practice for Ultrasonic Pulse-Echo Straight-Beam
2 4.1.4 Minimum equipment requirements, as in Table 1
Examination by the Contact Method
herein,
E 127 Practice for Fabricating and Checking Aluminum
2 4.1.5 Search unit size, frequency and type,
Alloy Ultrasonic Standard Reference Blocks
4.1.6 Couplant,
E 317 Practice for Evaluating Performance Characteristics
4.1.7 Automated turning, fixturing or scanning, or both, as
of Ultrasonic Pulse-Echo Testing Systems Without the Use
2 applicable,
of Electronic Measurement Systems
4.1.8 Type of reference block standards including surface
E 428 Practice for Fabrication and Control of Steel Refer-
2 curvature,
ence Blocks Used in Ultrasonic Inspection
4.1.9 Standardization details, including attenuation compen-
E 543 Practice for Evaluating Agencies that Perform Non-
2 sation and DAC techniques,
destructive Testing
4.1.10 The surfaces to be examined and the scanning path,
This guide is under the jurisdiction of ASTM Committee E-07 on Nondestruc-
tive Testing and is the direct responsibility of Subcommittee E07.06 on Ultrasonic Available from American National Standards Institute, 11 W. 42nd St., 13th
Method. Floor, New York, NY 10036.
Current edition approved August 10, 1997. Published January 1998. Available from Standardization Documents Order Deck, Bldg. 4 Section D, 700
Annual Book of ASTM Standards, Vol 03.03. Robbins Ave., Philadelphia, PA 19111–5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1901–97
TABLE 1 Minimum Equipment Requirements (Longitudinal Wave)
7.1.1 Electronic Equipment—The electronic equipment
Ultrasonic Test shall be capable of producing and processing electronic signals
Instrument Characteristics Frequency MHZ
at frequencies in the range of the search unit frequencies being
(Record)
used. The equipment and its display shall provide characteris-
Vertical limit, in. (mm) or percent
tics as listed in Table 1, that are suitable for the specific
of full screen height
application at the specified frequency, as determined in accor-
Upper vertical linearity limit in. (mm)
or percent of full screen height
dance with the procedures and tolerances described in Practice
Lower vertical linearity limit in. (mm)
E 317. The equipment, including the search unit, shall be
or percent of full screen height
capable of producing echo amplitudes of at least 60 % of full
Ultrasonic sensitivity, hole size,
64 ths, distance, in (mm)
screen height from the reference reflector required for the
Entry surface resolution, in. (mm)
examination, with the material noise level, from front to back
Back surface resolution in. (mm)
surface not exceeding 20 % of full screen height. Alternatively,
Horizontal limit, in. (mm) or
percent of full screen width
if these conditions can be met at one half the part thickness, the
Horizontal linearity range, in. (mm)
part may be inspected from both sides.
or percent of full screen width
NOTE 1—The using parties should agree on the minimum instrument
characteristics prior to conducting an examination.
4.1.11 Acceptance standards,
7.1.2 Voltage Regulator—If fluctuations in line voltage
4.1.12 Personnel certification level, and
cause indication amplitude variations exceeding +/– ⁄2 dB, a
4.1.13 Instrument characteristics.
voltage regulator shall be required on the power source. This
4.2 Written Procedure—Ultrasonic examinations performed
requirement is not applicable to battery-operated units.
in accordance with this guide shall be detailed in a written
7.1.3 Search Units—The search unit selected shall be ca-
procedure. Documentation of procedure qualification shall be
pable of transmitting and receiving ultrasound at the required
maintained by the preparer. Procedures shall be sufficiently
frequencies and energy levels necessary for discontinuity
detailed so that other qualified examiners may duplicate the
detection in the material being examined. The search units
examination and obtain equivalent results.
shall be of the contact type. Only longitudinal wave, straight
4.3 Personnel Qualifications—Personnel performing ultra-
beam, non-focused search units should be used. Dual element
sonic examinations in accordance with this guide shall be
search units may provide better near-surface resolution and
qualified in accordance with a nationally recognized NDT
detection of small discontinuities. Generally, round or rectan-
personnel qualification practice or standard; such as SNT-TC-
gular search units are used for examination whereas round
1A, ANSI/ASNT CP-189, MIL-STD-410, or a similar docu-
search units with symmetrical sound beam patterns are used for
ment. The practice or standard used and its applicable revision
evaluation. Typical search unit sizes range from ⁄8 in. (3.2 mm)
shall be specified in the contractual agreement between the
in diameter to 1- ⁄8 in. (28.6 mm) in diameter with other sizes
using parties.
and shapes available for special applications. Search units may
4.4 If specified in the contractual agreement, NDT agencies
be fitted with contoured shoes to enhance coupling with curved
shall be qualified and evaluated as described in Practice E 543.
surfaces.
5. Summary of Guide
7.1.4 Alarm(s)—For the examination of parts with regular
shape and parallel surfaces such as machined cylinders, rounds,
5.1 This guide describes a means for obtaining an evalua-
bars, forgings, etc. an audible/visual alarm may be used in
tion of discontinuities in materials by contact examination
conjunction with visual monitoring of the display for the
using longitudinal waves. Equipment, reference standards,
detection of discontinuities or for the monitoring and detection
examination and evaluation procedures, and documentation of
of loss of back surface reflection, or both. The alarm should be
results are described in detail.
adjustable to allow triggering at commonly required indication
6. Significance and Use
amplitudes, back-echo heights, and depths. During examina-
tion the audible visual alarm shall be easily detectable by the
6.1 This guide provides procedures for the application of
operator.
contact straight-beam examination for the detection and quan-
7.1.4.1 When reduction in the amplitude of back-surface
titative evaluation of discontinuities in materials.
reflection is monitored simultaneously with the detection of
6.2 Although not all requirements of this guide can be
lower amplitude signals from small, discrete discontinuities,
applied universally to all inspections, situations, and materials,
two separate gate/alarm systems are required. The negative
it does provide basis for establishing contractual criteria
slaved alarm system may also provide for a significantly lower
between the users, and may be used as a general guide for
receiver gain at the gated depth to avoid back-echo saturation.
preparing detailed specifications for a particular application.
See 10.1 and 10.4.
6.3 This guide is directed towards the evaluation of discon-
7.1.4.2 For some applications it may be advantageous to
tinuities detectable with the beam normal to the entry surface.
utilize a flaw gate system in which the echo-amplitude alarm
If discontinuities or other orientations are of concern, alternate
level can be varied as a function of target depth. Refer to
scanning techniques are required.
distance/amplitude gate (DAG) in 9.3.2.1.
7. Apparatus
7.2 Couplant—A couplant, usually a liquid or semi-liquid,
7.1 Apparatus shall include the following: is required between the face of the search unit and the
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1901–97
examination surface to permit transmittance of ultrasound from liquid-filled flexible tire. A minimum amount of couplant
the search unit into the material under examination. Typical provides for ultrasonic transmission into the examination
couplants include water, cellulose gel, oil and grease. Corro- surface since the elastic tire material is in rolling contact and
sion inhibitors or wetting agents or both may be used. conforms closely to the surface.
Couplants selected must not be detrimental to the product or 7.3 Reference Standards—The production item itself may
the process. The same couplant used for standardization shall be an adequate standard using the height of the back-wall echo
be used for the examination. During the performance of a for reference. For more quantitative information, charts such as
contact ultrasonic examination, the couplant layer between (AVG-DGS) representing distance-amplitude relationships of
search unit and examination material must be maintained such known reflector sizes for a particular search unit, frequency
that the contact area is held constant while maintaining and material may be used for standardization and evaluation of
adequate couplant thickness. Lack of couplant that will reduce discontinuities.
the effective contact area, or excess couplant, will reduce the 7.3.1 Reference Blocks—Ultrasonic reference blocks, often
amount of energy transferred between the search unit and the called test blocks, are used to standardize the ultrasonic
examination surface. These couplant variations, in turn, result equipment and to evaluate the indications received from
in examination sensitivity variations. discontinuities within the part. The ultrasonic characteristics of
7.2.1 The couplant should be selected such that its viscosity the reference blocks such as attenuation, noise level, surface
is appropriate for the surface finish of the material to be condition, and sound velocity, should be similar to the material
examined. The examination of rough surfaces generally re- to be examined. Standardization verifies that the instrument
quires a high-viscosity couplant and will result in some search unit is performing as required and establishes a detec-
deterioration of near-surface discontinuity detection. The tem- tion level for discontinuities.
perature of the material surface can change the couplant’s 7.3.2 Flat Blocks—The three most commonly used sets of
viscosity as in the case of oil and grease. See Table 2 for the reference block are area-amplitude set, containing blocks with
suggested viscosity of oil couplants for given surface rough- the same material path and various sizes of reference reflectors;
nesses. distance-amplitude set, containing blocks with one size refer-
7.2.2 At elevated temperatures as conditions warrant, heat- ence reflector at various material distances; and a combination
resistant coupling materials such as silicone oils, gels, or including both area-amplitude and distance-amplitude blocks
greases should be used. Further, intermittent contact of the in one set. These sets are described in Practices E 127 and
search unit with the part surface or auxiliary cooling of the E 428.
search unit may be necessary to avoid temperature changes that 7.3.3 Curved Surfaces—Reference blocks with flat surfaces
affect the ultrasonic characteristics of the search unit. At higher may be used for establishing gain settings for examinations on
temperatures, certain couplants based on inorganic salts or concave test surfaces and convex surfaces with radii of
thermoplastic organic materials, high-temperature delay mate- curvature 4 in. (101.6 mm) or greater. For convex surfaces with
rials (shoes) and search units that are not affected by high radii of curvature less than 4 in. (101.6 mm) it is recommended
temperatures may be required. that reference blocks with approximately the same nominal
7.2.3 Where constant coupling over large areas is required, radius of curvature shall be used. Guide E 1158 illustrates
as in autom
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