ASTM E1888/E1888M-17

Standard Practice for Acoustic Emission Examination of Pressurized Containers Made of Fiberglass Reinforced Plastic with Balsa Wood Cores

SIGNIFICANCE AND USE
4.1 This practice does not rely on absolute quantities of AE parameters. It relies on trends of cumulative AE counts that are measured during a specified sequence of loading cycles. This practice includes an example of examination settings and acceptance criteria as a nonmandatory appendix.  
FIG. 1 Recommended Features of the Apparatus  
4.2 Acoustic emission (AE) counts were used as a measure of AE activity during development of this practice. Cumulative hit duration may be used instead of cumulative counts if a correlation between the two is determined. Several processes can occur within the structure under examination. Some may indicate unacceptable flaws (for example, growing resin cracks, fiber fracture, delamination). Others may produce AE but have no structural significance (for example, rubbing at interfaces). The methodology described in this practice prevents contamination of structurally significant data with emission from insignificant sources.  
4.3 Background Noise—Background noise can distort interpretations of AE data and can preclude completion of an examination. Examination personnel should be aware of sources of background noise at the time examinations are conducted. AE examinations should not be conducted until such noise is substantially eliminated.  
4.4 Mechanical Background Noise—Mechanical background noise is generally induced by structural contact with the container under examination. Examples are: personnel contact, wind borne sand or rain. Also, leaks at pipe connections may produce background noise.  
4.5 Electronic Noise—Electronic noise such as electromagnetic interference (EMI) and radio frequency interference (RFI) can be caused by electric motors, overhead cranes, electrical storms, welders, etc.  
4.6 Airborne Background Noise—Airborne background noise can be produced by gas leaks in nearby equipment.  
4.7 Accuracy of the results from this practice can be influenced by factors related to setup and calibration of instrume...
SCOPE
1.1 This practice covers guidelines for acoustic emission (AE) examinations of pressurized containers made of fiberglass reinforced plastic (FRP) with balsa cores. Containers of this type are commonly used on tank trailers for the transport of hazardous chemicals.  
1.2 This practice is limited to cylindrical shape containers, 0.5 m [20 in.] to 3 m [120 in.] in diameter, of sandwich construction with balsa wood core and over 30 % glass (by weight) FRP skins. Reinforcing material may be mat, roving, cloth, unidirectional layers, or a combination thereof. There is no restriction with regard to fabrication technique or method of design.  
1.3 This practice is limited to containers that are designed for less than 0.520 MPa [75.4 psi] (gage) above static pressure head due to contents.  
1.4 This practice does not specify a time interval between examinations for re-qualification of a pressure container.  
1.5 This practice is used to determine if a container is suitable for service or if follow-up NDT is needed before that determination can be made.  
1.6 Containers that operate with a vacuum are not within the scope of this practice.  
1.7 Repair procedures are not within the scope of this practice.  
1.8 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.9 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. Specific precautionary statements are given in Section 8.  
1.10 This international standard was developed in accordance w...

General Information

• Status: Published
• Publication Date: 31-May-2017
• ICS: 17.140.20 - Noise emitted by machines and equipment
• ICS: 23.020.10 - Stationary containers and tanks
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.04 - Acoustic Emission Method

Relations

• Replaces: ASTM E1888/E1888M-12 - Standard Practice for Acoustic Emission Examination of Pressurized Containers Made of Fiberglass Reinforced Plastic with Balsa Wood Cores
• Effective Date: 01-Jun-2017
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-19b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2019
• Refers: ASTM E1316-19 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Mar-2019
• Refers: ASTM E1316-18 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jan-2018
• Refers: ASTM E1316-17a - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2017
• Refers: ASTM E1316-17 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2017
• Refers: ASTM E1316-16a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Aug-2016
• Refers: ASTM E1316-16 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2016
• Refers: ASTM E2374-15 - Standard Guide for Acoustic Emission System Performance Verification
• Effective Date: 01-Dec-2015
• Refers: ASTM E1316-15a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2015
• Refers: ASTM E1316-15 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2015
• Refers: ASTM E1316-14 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-14e1 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-13d - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2013

Overview

ASTM E1888/E1888M-17 is the internationally recognized standard practice for the acoustic emission (AE) examination of pressurized containers made of fiberglass reinforced plastic (FRP) with balsa wood cores. Developed by ASTM, this standard provides detailed guidelines for nondestructive testing (NDT) of cylindrical FRP containers-particularly those found on tank trailers transporting hazardous chemicals. The practice is specifically intended for containers with sandwich construction (balsa wood core and over 30% glass by weight in the FRP skins), and covers diameters from 0.5 m to 3 m, with maximum operating pressures below 0.520 MPa (75.4 psi) (gauge).

This standard offers a practical and effective methodology for evaluating the structural integrity of FRP pressure containers without relying on absolute values for AE emissions. Instead, it focuses on cumulative AE trends recorded during specified loading cycles, helping inspectors determine whether a container is suitable for continued use or requires further NDT before making service decisions.

---

Key Topics

• Scope of Application

  • Examines cylindrical FRP containers with balsa wood cores
  • Applicable to diameters from 0.5 m [20 in.] to 3 m [120 in.]
  • Suitable for containers operating at less than 0.520 MPa [75.4 psi] above static pressure head

• Acoustic Emission (AE) Monitoring

  • Focuses on trends in cumulative AE counts during controlled pressure cycles
  • Addresses sources of both significant (e.g., fiber fracture, resin cracks, delamination) and insignificant AE (e.g., interface rubbing)
  • Emphasizes minimizing background noise (mechanical, electronic, airborne) for accurate data interpretation

• Personnel and Equipment Requirements

  • Operators should be qualified according to recognized NDT certification schemes (e.g., ANSI/ASNT SNT-TC-1A, CP-189, NAS-410, ISO 9712)
  • Recommends specific apparatus features, calibration, and verification procedures to ensure equipment performance
  • Detailed procedures for sensor placement, data acquisition, and reporting

• Trends and Acceptance Criteria

  • Uses AE trend numbers rather than absolute emission values
  • Cumulative AE hit durations may substitute for counts if validated
  • Acceptance based on normalized trends through sequential loading-unloading cycles

---

Applications

ASTM E1888/E1888M-17 is widely used for in-service inspection, qualification, and periodic re-examination of FRP pressure containers in industries handling hazardous chemicals, including:

• Road and Rail Tanker Inspection

  • Ensures structural integrity of FRP tanks and containers used in chemical transport
  • Detects early-stage damage such as cracks, delamination, and fiber failures before catastrophic failure

• Industrial Chemical Storage

  • Assists facility managers in qualifying new and refurbished FRP tanks prior to commissioning
  • Provides a standardized approach for ongoing integrity assessments

• Regulatory Compliance and Safety Assurance

  • Facilitates adherence to legal and industry safety requirements for chemical and hazardous materials containment
  • Helps asset owners document condition and maintenance records through standardized reporting

Using this standard enables organizations to confidently assess the serviceability of FRP containers, extend equipment lifecycle, ensure transportation safety, and maintain compliance with international safety standards.

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Related Standards

ASTM E1888/E1888M-17 is part of a broader framework of nondestructive testing and pressure vessel examination standards, including:

• ASTM E1067 – Practice for Acoustic Emission Examination of FRP Resin Tanks/Vessels
• ASTM E543 – Specification for Agencies Performing Nondestructive Testing
• ASTM E976 – Guide for Determining Reproducibility of Acoustic Emission Sensor Response
• ASTM E1316 – Terminology for Nondestructive Examinations
• ISO 9712 – Non-Destructive Testing: Qualification and Certification of NDT Personnel
• ANSI/ASNT SNT-TC-1A – Personnel Qualification and Certification in Nondestructive Testing
• ASME Boiler & Pressure Vessel Code Section V, Article 11 – Non-destructive Examination Requirements

By referencing ASTM E1888/E1888M-17 alongside these related standards, professionals ensure comprehensive, reliable, and compliant acoustic emission testing of FRP containers.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1888/E1888M − 17
Standard Practice for
Acoustic Emission Examination of Pressurized Containers
Made of Fiberglass Reinforced Plastic with Balsa Wood
Cores
ThisstandardisissuedunderthefixeddesignationE1888/E1888M;thenumberimmediatelyfollowingthedesignationindicatestheyear
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.9 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This practice covers guidelines for acoustic emission
responsibility of the user of this standard to establish appro-
(AE)examinationsofpressurizedcontainersmadeoffiberglass
priate safety and health practices and determine the applica-
reinforced plastic (FRP) with balsa cores. Containers of this
bility of regulatory limitations prior to use. Specific precau-
type are commonly used on tank trailers for the transport of
tionary statements are given in Section 8.
hazardous chemicals.
1.10 This international standard was developed in accor-
1.2 This practice is limited to cylindrical shape containers,
dance with internationally recognized principles on standard-
0.5 m [20 in.] to 3 m [120 in.] in diameter, of sandwich
ization established in the Decision on Principles for the
construction with balsa wood core and over 30% glass (by
Development of International Standards, Guides and Recom-
weight) FRP skins. Reinforcing material may be mat, roving,
mendations issued by the World Trade Organization Technical
cloth, unidirectional layers, or a combination thereof. There is
Barriers to Trade (TBT) Committee.
norestrictionwithregardtofabricationtechniqueormethodof
design.
2. Referenced Documents
1.3 This practice is limited to containers that are designed
2.1 ASTM Standards:
for less than 0.520 MPa [75.4 psi] (gage) above static pressure
E543Specification forAgencies Performing Nondestructive
head due to contents.
Testing
1.4 This practice does not specify a time interval between
E976GuideforDeterminingtheReproducibilityofAcoustic
examinations for re-qualification of a pressure container.
Emission Sensor Response
E1067PracticeforAcousticEmissionExaminationofFiber-
1.5 This practice is used to determine if a container is
glass Reinforced Plastic Resin (FRP) Tanks/Vessels
suitable for service or if follow-up NDT is needed before that
E1106Test Method for Primary Calibration of Acoustic
determination can be made.
Emission Sensors
1.6 Containersthatoperatewithavacuumarenotwithinthe
E1316Terminology for Nondestructive Examinations
scope of this practice.
E1781Practice for Secondary Calibration ofAcoustic Emis-
1.7 Repair procedures are not within the scope of this
sion Sensors
practice.
E2374Guide for Acoustic Emission System Performance
Verification
1.8 The values stated in either SI units or inch-pound units
2.2 SPI/CARP Standards:
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each Recommended Practice for Acoustic Emission Testing of
system shall be used independently of the other. Combining Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
values from the two systems may result in non-conformance Recommended Practice for Acoustic Emission Testing of
with the standard. Fiberglass Reinforced Plastic Piping Systems
1 2
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
structive Testing and is the direct responsibility of Subcommittee E07.04 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Acoustic Emission Method. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved June 1, 2017. Published June 2017. Originally the ASTM website.
approved in 1997. Last previous edition approved in 2012 as E1888/E1888M-12. Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
DOI: 10.1520/E1888_E1888M-17. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1888/E1888M − 17
FIG. 1 Recommended Features of the Apparatus
2.3 ANSI/ASNT Standards: 3.2.2 Minimum AE activity level—that level of activity
SNT-TC-1ARecommended Practice for Personnel Qualifi- belowwhichAEtrendnumbersarenotrobustindicatorsofthe
cation and Certification in Nondestructive Testing trend (see 9.1)
ANSI/ASNTCP-189Standard for Qualification and Certifi-
3.2.3 Examination pressure—the highest pressure used
cation of NDT Personnel
while examining a given container. The examination pressure
2.4 AIA Standard:
is1.1timesthemaximumallowableworkingpressure,MAWP
NAS-410Nondestructive Testing Personnel Qualification
(see Section 8).
and Certification
4. Significance and Use
2.5 ASME Standard:
Section V, Article 11,Boiler and Pressure Vessel Code
4.1 This practice does not rely on absolute quantities ofAE
2.6 ISO Standard:
parameters.ItreliesontrendsofcumulativeAEcountsthatare
ISO 9712Non-Destructive Testing: Qualification and Certi-
measured during a specified sequence of loading cycles. This
fication of NDT Personnel
practice includes an example of examination settings and
acceptance criteria as a nonmandatory appendix.
3. Terminology
4.2 Acoustic emission (AE) counts were used as a measure
3.1 Definitions—With the exception of terms defined in 3.2,
ofAEactivityduringdevelopmentofthispractice.Cumulative
this practice incorporates by reference all terminology in
hit duration may be used instead of cumulative counts if a
Terminology E1316 and Practice E1067. First occurrences of
correlation between the two is determined. Several processes
terms defined herein are italicized.
can occur within the structure under examination. Some may
indicate unacceptable flaws (for example, growing resin
3.2 Definitions of Terms Specific to This Standard:
cracks, fiber fracture, delamination). Others may produce AE
3.2.1 AE trend number—a number used to designate trends
but have no structural significance (for example, rubbing at
inAE activity which are exhibited by structures during a set of
interfaces). The methodology described in this practice pre-
repeated loading cycles (see 9.2).
vents contamination of structurally significant data with emis-
sion from insignificant sources.
AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
4.3 Background Noise—Background noise can distort inter-
28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
pretations of AE data and can preclude completion of an
Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
examination. Examination personnel should be aware of
sources of background noise at the time examinations are
Available from American Society of Mechanical Engineers (ASME), ASME
conducted. AE examinations should not be conducted until
International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
www.asme.org. such noise is substantially eliminated.
Available from International Organization for Standardization (ISO), ISO
4.4 Mechanical Background Noise—Mechanical back-
Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,
Geneva, Switzerland, http://www.iso.org. groundnoiseisgenerallyinducedbystructuralcontactwiththe
E1888/E1888M − 17
FIG. 2 Typical Examination Configuration Showing AE Sensor Location on a Road Tanker
containerunderexamination.Examplesare:personnelcontact, 5.2.2.6 Examination report and permanent record require-
wind borne sand or rain. Also, leaks at pipe connections may ments.
produce background noise.
5.3 Qualification of Nondestructive Agencies—If specified
4.5 Electronic Noise—Electronic noise such as electromag- in the contractual agreement, NDT agencies shall be qualified
netic interference (EMI) and radio frequency interference and evaluated as described in Practice E543. The applicable
(RFI) can be caused by electric motors, overhead cranes, edition of Practice E543 shall be specified in the contractual
electrical storms, welders, etc. agreement.
4.6 Airborne Background Noise—Airborne background 5.4 Timing of Examination—The timing of examination
noise can be produced by gas leaks in nearby equipment. shall be in accordance with 1.4 – 1.7 unless otherwise
specified.
4.7 Accuracy of the results from this practice can be
influenced by factors related to setup and calibration of 5.5 Procedures and Techniques—The procedures and tech-
instrumentation, background noise, material properties, and niques to be utilized shall be specified in the contractual
structural characteristics. agreement.
5.6 Extent of Examination—Theextentofexaminationshall
5. Basis of Application
be in accordance with paragraph 1.2, unless otherwise speci-
5.1 The following items are subject to contractual agree-
fied.
ment between the parties using or referencing this practice.
5.7 Reporting Criteria/Acceptance Criteria—Reporting
5.2 Personnel Qualification:
criteria/acceptancecriteriashallbeinaccordancewithSections
5.2.1 If specified in the contractual agreement, personnel
9 and 10 unless otherwise specified.
performing examinations to this practice shall be qualified in
5.8 Reexamination of Repaired/Reworked Items—
accordance with a nationally or internationally recognized
Reexamination of repaired/reworked items is not addressed in
NDT personnel qualification practice or standard such as
thispracticeandifrequiredshallbespecifiedinthecontractual
ANSI/ASNTCP-189, SNT-TC-1A, NAS-410, ISO 9712, or a
agreement.
similar document and certified by the employer or certifying
agency, as applicable. The practice or standard used and its
6. Apparatus
applicable revision shall be identified in the contractual agree-
6.1 Recommended features of the apparatus required for
ment between the using parties.
5.2.2 Also, it is required that personnel performing acoustic this practice are provided in Fig. 1. Full specifications are in
Annex A1.
emission examination of containers be trained, by attending a
dedicated training course on the subject and passing a written
6.2 Couplant must be used to acoustically connect sensors
examination. The training course shall include appropriate
to the vessel surface. Adhesives that have acceptable acoustic
material for NDT Level II qualification in accordance with a
properties and adhesives used in combination with traditional
recognized NDT personnel qualification practice or standard
couplants are acceptable.
per5.2.1.Personnelshallbetrained/examinedonthefollowing
6.3 Sensors may be held in place with elastic straps,
topics:
adhesive tape, or other mechanical means.
5.2.2.1 Container construction and terminology,
5.2.2.2 Mechanisms of AE generation in FRP including 6.4 Sensor spacing shall be such that a standard 0.5 mm
containers within the scope of this practice, [0.02 in.], 2H pencil lead break (See Guide E976) on any part
5.2.2.3 AE instrumentation, ofaliquidfilledcontainerisdetectedbyatleastoneAEsensor.
5.2.2.4 Container examination procedures, including load- A0.3mm[0.012in.],2Hpencilleadbreakmaybeusedwhich
ing requirements, wouldreducethesensorspacing.Presenceofheads,manholes,
5.2.2.5 Data collection and interpretation, and and nozzles shall be considered when sensor locations are
E1888/E1888M − 17
selected. Fig. 2 shows a typical sensor location scheme for a 7. Calibration and System Performance Verification
vessel of 10.8 m [424 in.] length and 1.8 m [72 in.] diameter.
7.1 Perform annual calibration and verification of pressure
6.4.1 Attenuation Characterization—Typical signal propa-
transducers, AE sensors, preamplifiers (if applicable), signal
gation losses shall be determined according to the following
processor(particularlythesignalprocessortimereference)and
procedure. This procedure provides a relative measure of the
AE electronic waveform generator.Adjust equipment so that it
attenuation but may not be representative of a genuine AE
conforms to equipment manufacturer’s specifications. Instru-
source. It should be noted that the peak amplitude from a
ments used for calibrations must have current accuracy certi-
mechanical pencil lead break may vary with surface hardness,
fication that is traceable to the National Institute for Standards
resin condition and cure. Select a representative region of the
and Technology (NIST).
vesselwithclearaccessalongthecylindricalsection.Mountan
7.2 Perform routine electronic evaluations on a monthly
AE sensor and mark off distances of 15 cm [6 in.] and 30 cm
basis, before each examination or at any time there is concern
[12in.]fromthecenterofthesensoralongalineparalleltothe
about signal processor performance. Use an AE electronic
principal direction of the surface fiber. Select two additional
waveform generator in making evaluations. Each signal pro-
points on the surface of the vessel at 15 cm [6 in.] and 30 cm
cessor channel must respond with peak amplitude reading
[12 in.] along a line inclined 45 and 90° to the principal
within 62 dB of the expected output value (based on input
directionofthesurfacefiber,breakpencilleads(0.3mm[0.012
signal value and amplifier gain values).
in.] 2H, rather then 0.5 mm [0.02 in.] to avoid possible
saturation due to larger signal output) and record peak ampli- 7.3 Perform routine evaluation of each sensor on a monthly
tude.Allleadbreaksshallbedoneatanangleofapproximately basis, before each examination, or at any time there is concern
30° to the surface with a 2.54 mm [0.1 in.] lead extension.The about the sensors performance. Record peak amplitude re-
sponseandelectronicnoiselevel.Sensorscanbestimulatedby
attenuation data shall be retained as part of the original
experimental record. a pencil lead break or electronic waveform generator with a
pulser. Replace sensors that are found to have peak amplitudes
6.4.2 Inaddition,recordthedistancesfromthecenterofthe
or electronic noise more than 5 dB greater or less than the
sensor to the points where hits are no longer detected. Repeat
average of the group of sensors to be used during the
this procedure along lines inclined 45 and 90° to the direction
examination.
of the original line. The data shall be retained as part of the
original experimental record. The minimum distance from the
7.4 A system performance verification must be conducted
sensoratwhichthepencilleadbreakcannolongerbedetected
immediately before and immediately after each examination
is known as the threshold distance.
(see Guide E2374). A performance check uses a mechanical
devicetoinducestresswavesintothevesselwallataspecified
6.5 Acoustic emission sensors are used to detect strain
distance from each sensor. Induced stress waves stimulate a
induced stress waves produced by discontinuities. Sensors
sensor in the same way as emission from a discontinuity.
mustbeheldincontactwiththevesselwalltoensureadequate
Performance checks verify performance of the entire system
acoustic coupling.
(including couplant).
6.6 Apreamplifiermaybeenclosedinthesensorhousingor
7.4.1 Thepreferredtechniqueforconductingaperformance
inaseparateenclosure.Ifaseparatepreamplifierisused,cable
check is a pencil lead break. Lead should be broken on the
length between sensor and preamplifier must not exceed 2 m
vessel surface no less than 10 cm [4 in.] from the sensor.A2H
[78 in.].
lead, 0.3 mm [0.012 in.] diameter, with a 2–3 mm [0.08–0.12
in.] long lead extension should be used (see Fig 4–5 of Guide
6.7 Power/signal cable length (that is, cable between pre-
E976).
amplifierandsignalprocessor)shallnotexceed150m[500ft].
6.8 Signal processors are computerized instruments with
8. Procedure
independent channels that filter, measure and convert analog
8.1 Use liquid (normally water) for the pressure medium.
information into digital form for display and permanent stor-
Support containers that are not mounted on a truck frame (as
age.Asignalprocessormusthavesufficientspeedandcapacity
closely as is practical) like in service. Support shall be such as
to independently process data from all sensors simultaneously.
to minimize extraneous noise. Examination data are used to
Thesignalprocessorshouldprovidecapabilitytofilterdatafor
compute “AE trend numbers”. These can be computed while
replay.
the examination is in progress. These are defined in 9.2.
6.9 A video monitor should display processed data in
8.1.1 Apply pre-examination simulated AE to the (liquid
various formats. Display format may be selected by the
filled) container 200 mm [7.9 in.] from each sensor. Include
examiner.
simulatedAE counts in examination reports. Make at least five
lead breaks, along a 20 cm [8 in.] radius circle, around each
6.10 Adatastoragedevice,suchasaharddiscorremovable
sensor.Their average shall be at least N counts per lead break
c
media device, may be used to access data for replay or for
(see X2.2). If fewer counts are measured, examine the system
archival.
and identify sensor, cable, electronics, coupling or vessel
6.11 Hardcopy
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1888/E1888M − 12 E1888/E1888M − 17
Standard Practice for
Acoustic Emission Examination of Pressurized Containers
Made of Fiberglass Reinforced Plastic with Balsa Wood
Cores
This standard is issued under the fixed designation E1888/E1888M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This practice covers guidelines for acoustic emission (AE) examinations of pressurized containers made of fiberglass
reinforced plastic (FRP) with balsa cores. Containers of this type are commonly used on tank trailers for the transport of hazardous
chemicals.
1.2 This practice is limited to cylindrical shape containers, 0.5 m [20 in.] to 3 m [120 in.] in diameter, of sandwich construction
with balsa wood core and over 30 % glass (by weight) FRP skins. Reinforcing material may be mat, roving, cloth, unidirectional
layers, or a combination thereof. There is no restriction with regard to fabrication technique or method of design.
1.3 This practice is limited to containers that are designed for less than 0.520 MPa [75.4 psi] (gage) above static pressure head
due to contents.
1.4 This practice does not specify a time interval between examinations for re-qualification of a pressure container.
1.5 This practice is used to determine if a container is suitable for service or if follow-up NDT is needed before that
determination can be made.
1.6 Containers that operate with a vacuum are not within the scope of this practice.
1.7 Repair procedures are not within the scope of this practice.
1.8 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.9 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. Specific precautionary statements are given in Section 8.
1.10 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E543 Specification for Agencies Performing Nondestructive Testing
E750 Practice for Characterizing Acoustic Emission Instrumentation
E976 Guide for Determining the Reproducibility of Acoustic Emission Sensor Response
E1067 Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
E1106 Test Method for Primary Calibration of Acoustic Emission Sensors
E1316 Terminology for Nondestructive Examinations
E1781 Practice for Secondary Calibration of Acoustic Emission Sensors
This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic Emission
Method.
Current edition approved June 15, 2012June 1, 2017. Published July 2012June 2017. Originally approved in 1997. Last previous edition approved in 20072012 as
E1888/E1888M - 07.E1888/E1888M - 12. DOI: 10.1520/E1888_E1888M-12.10.1520/E1888_E1888M-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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E2374 Guide for Acoustic Emission System Performance Verification
2.2 SPI/CARP Standards:
Recommended Practice for Acoustic Emission Testing of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
Recommended Practice for Acoustic Emission Testing of Fiberglass Reinforced Plastic Piping Systems
2.3 ANSI/ASNT Standards:
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing
ANSI/ASNT CP-189 Standard for Qualification and Certification of NDT Personnel
2.4 AIA Standard:
NAS-410 Nondestructive Testing Personnel Qualification and Certification
2.5 ASME Standard:
Section V, Article 11, Boiler and Pressure Vessel Code
2.6 ISO Standard:
ISO 9712 Non-Destructive Testing: Qualification and Certification of NDT Personnel
3. Terminology
3.1 Definitions—With the exception of terms defined in 3.2, this practice incorporates by reference all terminology in
Terminology E1316 and Practice E1067. First occurrences of terms defined herein are italicized.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 AE trend number—a number used to designate trends in AE activity which are exhibited by structures during a set of
repeated loading cycles (see 9.2).
3.2.2 Minimum AE activity level—that level of activity below which AE trend numbers are not robust indicators of the trend (see
9.1)
3.2.3 Examination pressure—the highest pressure used while examining a given container. The examination pressure is 1.1
times the maximum allowable working pressure, MAWP (see Section 8).
4. Significance and Use
4.1 This practice does not rely on absolute quantities of AE parameters. It relies on trends of cumulative AE counts that are
measured during a specified sequence of loading cycles. This practice includes an example of examination settings and acceptance
criteria as a nonmandatory appendix.
4.2 Acoustic emission (AE) counts were used as a measure of AE activity during development of this practice. Cumulative hit
duration may be used instead of cumulative counts if a correlation between the two is determined. Several processes can occur
within the structure under examination. Some may indicate unacceptable flaws (for example, growing resin cracks, fiber fracture,
delamination). Others may produce AE but have no structural significance (for example, rubbing at interfaces). The methodology
described in this practice prevents contamination of structurally significant data with emission from insignificant sources.
4.3 Background Noise—Background noise can distort interpretations of AE data and can preclude completion of an
examination. Examination personnel should be aware of sources of background noise at the time examinations are conducted. AE
examinations should not be conducted until such noise is substantially eliminated.
4.4 Mechanical Background Noise—Mechanical background noise is generally induced by structural contact with the container
under examination. Examples are: personnel contact, wind borne sand or rain. Also, leaks at pipe connections may produce
background noise.
4.5 Electronic Noise—Electronic noise such as electromagnetic interference (EMI) and radio frequency interference (RFI) can
be caused by electric motors, overhead cranes, electrical storms, welders, etc.
4.6 Airborne Background Noise—Airborne background noise can be produced by gas leaks in nearby equipment.
4.7 Accuracy of the results from this practice can be influenced by factors related to setup and calibration of instrumentation,
background noise, material properties, and structural characteristics.
5. Basis of Application
5.1 The following items are subject to contractual agreement between the parties using or referencing this practice.
5.2 Personnel Qualification:
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
www.asme.org.
Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, http://www.iso.org.
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FIG. 1 Recommended Features of the Apparatus
5.2.1 If specified in the contractual agreement, personnel performing examinations to this practice shall be qualified in
accordance with a nationally or internationally recognized NDT personnel qualification practice or standard such as ANSI/
ASNT CP-189, SNT-TC-1A, NAS-410, ISO 9712, or a similar document and certified by the employer or certifying agency, as
applicable. The practice or standard used and its applicable revision shall be identified in the contractual agreement between the
using parties.
5.2.2 Also, it is required that personnel performing acoustic emission examination of containers be trained, by attending a
dedicated training course on the subject and passing a written examination. The training course shall include appropriate material
for NDT Level II qualification in accordance with a recognized NDT personnel qualification practice or standard per 5.2.1.
Personnel shall be trained/examined on the following topics:
5.2.2.1 Container construction and terminology,
5.2.2.2 Mechanisms of AE generation in FRP including containers within the scope of this practice,
5.2.2.3 AE instrumentation,
5.2.2.4 Container examination procedures, including loading requirements,
5.2.2.5 Data collection and interpretation, and
5.2.2.6 Examination report and permanent record requirements.
5.3 Qualification of Nondestructive Agencies—If specified in the contractual agreement, NDT agencies shall be qualified and
evaluated as described in Practice E543. The applicable edition of Practice E543 shall be specified in the contractual agreement.
5.4 Timing of Examination—The timing of examination shall be in accordance with 1.4 – 1.7 unless otherwise specified.
5.5 Procedures and Techniques—The procedures and techniques to be utilized shall be specified in the contractual agreement.
5.6 Extent of Examination—The extent of examination shall be in accordance with paragraph 1.2, unless otherwise specified.
5.7 Reporting Criteria/Acceptance Criteria—Reporting criteria/acceptance criteria shall be in accordance with Sections 9 and
10 unless otherwise specified.
5.8 Reexamination of Repaired/Reworked Items—Reexamination of repaired/reworked items is not addressed in this practice
and if required shall be specified in the contractual agreement.
6. Apparatus
6.1 Recommended features of the apparatus required for this practice are provided in Fig. 1. Full specifications are in Annex
A1.
6.2 Couplant must be used to acoustically connect sensors to the vessel surface. Adhesives that have acceptable acoustic
properties and adhesives used in combination with traditional couplants are acceptable.
6.3 Sensors may be held in place with elastic straps, adhesive tape, or other mechanical means.
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FIG. 2 Typical Examination Configuration Showing AE Sensor Location on a Road Tanker
6.4 Sensor spacing shall be such that a standard 0.5 mm [0.02 in.], 2H pencil lead break (See Guide E976) on any part of a liquid
filled container is detected by at least one AE sensor. A 0.3 mm [0.012 in.], 2H pencil lead break may be used which would reduce
the sensor spacing. Presence of heads, manholes, and nozzles shall be considered when sensor locations are selected. Fig. 2 shows
a typical sensor location scheme for a vessel of 10.8 m [424 in.] length and 1.8 m [72 in.] diameter.
6.4.1 Attenuation Characterization—Typical signal propagation losses shall be determined according to the following
procedure. This procedure provides a relative measure of the attenuation but may not be representative of a genuine AE source.
It should be noted that the peak amplitude from a mechanical pencil lead break may vary with surface hardness, resin condition
and cure. Select a representative region of the vessel with clear access along the cylindrical section. Mount an AE sensor and mark
off distances of 15 cm [6 in.] and 30 cm [12 in.] from the center of the sensor along a line parallel to the principal direction of
the surface fiber. Select two additional points on the surface of the vessel at 15 cm [6 in.] and 30 cm [12 in.] along a line inclined
45 and 90° to the principal direction of the surface fiber, break pencil leads (0.3 mm [0.012 in.] 2H, rather then 0.5 mm [0.02 in.]
to avoid possible saturation due to larger signal output) and record peak amplitude. All lead breaks shall be done at an angle of
approximately 30° to the surface with a 2.54 mm [0.1 in.] lead extension. The attenuation data shall be retained as part of the
original experimental record.
6.4.2 In addition, record the distances from the center of the sensor to the points where hits are no longer detected. Repeat this
procedure along lines inclined 45 and 90° to the direction of the original line. The data shall be retained as part of the original
experimental record. The minimum distance from the sensor at which the pencil lead break can no longer be detected is known
as the threshold distance.
6.5 Acoustic emission sensors are used to detect strain induced stress waves produced by discontinuities. Sensors must be held
in contact with the vessel wall to ensure adequate acoustic coupling.
6.6 A preamplifier may be enclosed in the sensor housing or in a separate enclosure. If a separate preamplifier is used, cable
length between sensor and preamplifier must not exceed 2 m [78 in.].
6.7 Power/signal cable length (that is, cable between preamplifier and signal processor) shall not exceed 150 m [500 ft].
6.8 Signal processors are computerized instruments with independent channels that filter, measure and convert analog
information into digital form for display and permanent storage. A signal processor must have sufficient speed and capacity to
independently process data from all sensors simultaneously. The signal processor should provide capability to filter data for replay.
6.9 A video monitor should display processed data in various formats. Display format may be selected by the examiner.
6.10 A data storage device, such as a hard disc or removable media (CD, DVD, or other), device, may be used to provideaccess
data for replay or for archives.archival.
6.11 Hard copy capability should be available from a printer or equivalent output device.
7. Calibration and System Performance Verification
7.1 Perform annual calibration and verification of pressure transducer,transducers, AE sensors, preamplifiers (if applicable),
signal processor (particularly the signal processor time reference) and AE electronic waveform generator. Adjust equipment so that
it conforms to equipment manufacturer’s specifications. Instruments used for calibrations must have current accuracy certification
that is traceable to the National Institute for Standards and Technology (NIST).
7.2 Perform routine electronic evaluations on a monthly basis basis, before each examination or at any time there is concern
about signal processor performance. Use an AE electronic waveform generator in making evaluations. Each signal processor
channel must respond with peak amplitude reading within 62 dB of the expected output value (based on input signal value and
amplifier gain values).
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TABLE 1 Load Schedule
Cycle Number Maximum Pressure
1 ⁄3 Examination Pressure
2 ⁄3 Examination Pressure
3 to 6 Full Examination Pressure
7.3 Perform routine evaluation of each sensor on a monthly basis basis, before each examination, or at any time there is concern
about the sensors performance. Record peak amplitude response and electronic noise level. Sensors can be stimulated by a pencil
lead break or electronic waveform generator with a pulser. Replace sensors that are found to have peak amplitudes or electronic
noise more than 5 dB greater or less than the average of the group of sensors to be used during the examination.
7.4 A system performance verification must be conducted immediately before and immediately after each examination (see
Guide E2374). A performance check uses a mechanical device to induce stress waves into the vessel wall at a specified distance
from each sensor. Induced stress waves stimulate a sensor in the same way as emission from a discontinuity. Performance checks
verify performance of the entire system (including couplant).
7.4.1 The preferred technique for conducting a performance check is a pencil lead break. Lead should be broken on the vessel
surface no less than 10 cm [4 in.] from the sensor. A 2H lead, 0.3 mm [0.012 in.] diameter, with a 2–3 mm [0.08–0.12 in.] long
lead extension should be used (see Fig 4–5 of Guide E976).
8. Procedure
8.1 Use liquid (normally water) for the pressure medium. Support containers that are not mounted on a truck frame (as closely
as is practical) like in service. Support shall be such as to minimize extraneous noise. Examination data are used to compute “AE
trend numbers”. These can be computed while the examination is in progress. These are defined in 9.2.
8.1.1 Apply pre-examination simulated AE to the (liquid filled) container 200 mm [7.9 in.] from each sensor. Include simulated
AE counts in examination reports. Make at least five lead
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