ASTM E1067/E1067M-18

Standard Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels

SIGNIFICANCE AND USE
5.1 The AE examination method detects damage in FRP equipment. The damage mechanisms that are detected in FRP are as follows: resin cracking, fiber debonding, fiber pullout, fiber breakage, delamination, and bond failure in assembled joints (for example, nozzles, manways, and so forth). Flaws in unstressed areas and flaws that are structurally insignificant will not generate AE.  
5.2 This practice is convenient for on-line use under operating stress to determine structural integrity of in-service equipment usually with minimal process disruption.  
5.3 Indications located with AE should be examined by other techniques; for example, visual, ultrasound, dye penetrant, and so forth, and may be repaired and tested as appropriate. Repair procedure recommendations are outside the scope of this practice.
SCOPE
1.1 This practice covers acoustic emission (AE) examination or monitoring of fiberglass-reinforced plastic (FRP) tanks-vessels (equipment) under pressure or vacuum to determine structural integrity.  
1.2 This practice is limited to tanks-vessels designed to operate at an internal pressure no greater than 1.73 MPa absolute [250 psia, 17.3 bar] above the static pressure due to the internal contents. It is also applicable for tanks-vessels designed for vacuum service with differential pressure levels between 0 and 0.10 MPa [0 and 14.5 psi, 1 bar].  
1.3 This practice is limited to tanks-vessels with glass contents greater than 15 % by weight.  
1.4 This practice applies to examinations of new and in-service equipment.  
1.5 Units—The values stated in either SI units or inch-pound units are to be regarded 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.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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.

General Information

• Status: Published
• Publication Date: 31-Jan-2018
• 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 E1067/E1067M-11 - Standard Practice for Acoustic Emission Examination of Fiberglass Reinforced Plastic Resin (FRP) Tanks/Vessels
• Effective Date: 01-Feb-2018
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM E750-15(2020) - Standard Practice for Characterizing Acoustic Emission Instrumentation
• Effective Date: 01-Jun-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM E1316-19b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2019
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM E1316-19 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Mar-2019
• Refers: ASTM D883-19 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2019
• Refers: ASTM D883-18a - Standard Terminology Relating to Plastics
• Effective Date: 01-Dec-2018
• Refers: ASTM D883-18 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2018
• Refers: ASTM E1316-18 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jan-2018
• Refers: ASTM D883-17 - Standard Terminology Relating to Plastics
• Effective Date: 15-Aug-2017

Overview

ASTM E1067/E1067M-18, issued by ASTM International, outlines the standard practice for acoustic emission (AE) examination of fiberglass reinforced plastic resin (FRP) tanks and vessels. This non-destructive testing method assesses the structural integrity of FRP equipment under pressure or vacuum conditions. The standard is applicable to tanks and vessels with a glass content greater than 15% by weight and is suitable for both new and in-service equipment, operating at internal pressures not exceeding 1.73 MPa (250 psia, 17.3 bar) above the static pressure, or under vacuum with differential pressures up to 0.10 MPa (14.5 psi, 1 bar).

AE examination is a valuable technique for detecting active damage mechanisms within FRP materials, such as resin cracking, fiber debonding, fiber pullout, fiber breakage, delamination, and bond failure. The method enables real-time monitoring and can be performed with minimal disruption to operational processes.

Key Topics

• Damage Mechanisms Detected:

  • Resin cracking
  • Fiber debonding and pullout
  • Fiber breakage
  • Delamination
  • Bond failures in assembled joints (e.g., nozzles, manways)

• Method Characteristics:

  • AE detects only flaws in stressed or structurally significant areas
  • Unstressed or insignificant flaws do not typically generate AE signals
  • AE is most effective for on-line assessments under actual operating conditions

• Testing Procedure Highlights:

  • Tanks/vessels are subjected to programmed pressure or vacuum increases
  • Sensors detect stress waves (acoustic emissions) from structural flaws
  • Real-time displays assist in identifying potential structural issues
  • AE indications may require confirmation using complementary NDT methods (e.g., visual inspection, ultrasound, dye penetrant)

• Reporting and Documentation:

  • Test reports must detail equipment identification, sensor locations, testing sequence, results, and data records
  • Digital records are recommended for at least two years or as contractually specified

Applications

The ASTM E1067/E1067M-18 standard is widely used in industries where FRP tanks and vessels are critical to safety and operations, including:

• Chemical processing plants: To monitor and maintain the structural health of storage and processing tanks handling corrosive or hazardous materials.
• Water and wastewater treatment: For routine integrity assessment of FRP vessels under pressure or vacuum service.
• Petroleum and petrochemical facilities: Where FRP tanks are exposed to fluctuating loads and aggressive service environments.
• Power generation: For in-service monitoring of FRP components within cooling and process systems.

The AE method allows for cost-effective, in-service inspection, reducing downtime and helping facilities comply with regulatory and safety requirements. Early identification of damage can extend asset life and prevent catastrophic failures.

Related Standards

Several ASTM, ANSI/ASNT, and ISO standards are referenced in ASTM E1067/E1067M-18 to support acoustic emission examination and NDT personnel qualification:

• ASTM D883: Terminology relating to plastics
• ASTM E543: Specification for agencies performing nondestructive testing
• ASTM E650: Guide for mounting piezoelectric acoustic emission sensors
• ASTM E750: Practice for characterizing acoustic emission instrumentation
• ASTM E1106/E1781: Methods for calibration of acoustic emission sensors
• ASTM E1316: Terminology for nondestructive examinations
• ASTM E2075/E2374: Practices and guides for AE sensor and system verification
• ANSI/ASNT SNT-TC-1A/CP-189: Qualification and certification of NDT personnel
• AIA NAS-410: Certification for NDT personnel in aerospace
• ISO 9712: Non-destructive testing-Qualification and certification of NDT personnel

Employing the best practices outlined in ASTM E1067/E1067M-18, along with associated NDT standards, helps ensure safe, reliable, and compliant operation of FRP tanks and vessels across various industries.

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: E1067/E1067M − 18
Standard Practice for
Acoustic Emission Examination of Fiberglass Reinforced
Plastic Resin (FRP) Tanks/Vessels
ThisstandardisissuedunderthefixeddesignationE1067/E1067M;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* 2. Referenced Documents
1.1 This practice covers acoustic emission (AE) examina- 2.1 ASTM Standards:
tionormonitoringoffiberglass-reinforcedplastic(FRP)tanks-
D883Terminology Relating to Plastics
vessels (equipment) under pressure or vacuum to determine D5436Specification for Cast Poly(Methyl Methacrylate)
structural integrity. Plastic Rods, Tubes, and Shapes
E543Specification forAgencies Performing Nondestructive
1.2 This practice is limited to tanks-vessels designed to
Testing
operate at an internal pressure no greater than 1.73 MPa
E650Guide for Mounting Piezoelectric Acoustic Emission
absolute [250 psia, 17.3 bar] above the static pressure due to
Sensors
the internal contents. It is also applicable for tanks-vessels
E750Practice for Characterizing Acoustic Emission Instru-
designed for vacuum service with differential pressure levels
mentation
between 0 and 0.10 MPa [0 and 14.5 psi, 1 bar].
E1106Test Method for Primary Calibration of Acoustic
1.3 This practice is limited to tanks-vessels with glass
Emission Sensors
contents greater than 15% by weight.
E1316Terminology for Nondestructive Examinations
E2075Practice for Verifying the Consistency of AE-Sensor
1.4 This practice applies to examinations of new and in-
Response Using an Acrylic Rod
service equipment.
E1781Practice for Secondary Calibration ofAcoustic Emis-
1.5 Units—The values stated in either SI units or inch-
sion Sensors
poundunitsaretoberegardedasstandard.Thevaluesstatedin
E2374Guide for Acoustic Emission System Performance
each system may not be exact equivalents; therefore, each
Verification
system shall be used independently of the other. Combining
2.2 ANSI/ASNT Standards:
values from the two systems may result in non-conformance
SNT-TC-1A Recommended Practice for Nondestructive
with the standard.
Testing Personnel Qualification and Certification
1.6 This standard does not purport to address all of the
ANSI/ASNT CP-189Standard for Qualification and Certifi-
safety concerns, if any, associated with its use. It is the
cation of Nondestructive Testing Personnel
responsibility of the user of this standard to establish appro-
2.3 AIA Standard:
priate safety, health, and environmental practices and deter-
NAS-410Certification and Qualification of Nondestructive
mine the applicability of regulatory limitations prior to use.
Personnel (Quality Assurance Committee)
1.7 This international standard was developed in accor-
2.4 ISO Standard:
dance with internationally recognized principles on standard-
ISO 9712Non-Destructive Testing—Qualification and Cer-
ization established in the Decision on Principles for the
tification of NDT Personnel
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
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
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- the ASTM website.
structive Testing and is the direct responsibility of Subcommittee E07.04 on AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
Acoustic Emission Method. 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Current edition approved Feb. 1, 2018. Published February 2018. Originally Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
approved in 1985. Last previous edition approved in 2011 as E1067/E1067M–11. WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
DOI: 10.1520/E1067-18.
*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
E1067/E1067M − 18
3. Terminology 5.3 Indications located with AE should be examined by
other techniques; for example, visual, ultrasound, dye
3.1 Complete definitions of terms related to plastics and
penetrant, and so forth, and may be repaired and tested as
acoustic emission will be found in Terminology D883 and
appropriate. Repair procedure recommendations are outside
E1316.
the scope of this practice.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 FRP—fiberglass reinforced plastic, a glass-fiber poly-
6. Basis of Application
mer composite with certain mechanical properties superior to
6.1 The following items are subject to contractual agree-
those of the base resin.
ment between the parties using or referencing this practice:
3.2.2 operating pressure—the pressure at the top of a vessel
6.2 Personnel Qualification:
at which it normally operates. It shall not exceed the design
pressure and it is usually kept at a suitable level below the 6.2.1 If specified in the contractual agreement, personnel
performing examinations to this standard shall be qualified in
setting of the pressure-relieving devices to prevent their
frequent opening. accordance with a nationally or internationally recognized
NDT personnel qualification practice or standard such as
3.2.3 pressure, design—the pressure used in design to de-
ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712, or a
termine the required minimum thicknesses and minimum
similar document and certified by the employer or certifying
mechanical properties.
agency, as applicable. The practice or standard used and its
3.2.4 processor—a circuit that analyzes AE waveforms.
applicable revision shall be identified in the contractual agree-
(See Section 7 and A1.8.)
ment between the using parties.
3.2.5 summing amplifier (summer, mixer)—an operational
6.3 Qualification of Nondestructive Agencies—If specified
amplifier that produces an output signal equal to a weighted
in the contractual agreement, NDT agencies shall be qualified
sum of the input signals.
and evaluated as described in Practice E543. The applicable
3.2.6 zone—the area surrounding a sensor from which AE
edition of Practice E543 shall be specified in the contractual
can be detected by that sensor.
agreement.
4. Summary of Practice
6.4 Procedures and Techniques—The procedures and tech-
niques to be utilized shall be as specified in the contractual
4.1 This practice consists of subjecting equipment to in-
agreement.
creasing pressure or vacuum while monitoring with sensors
that are sensitive to acoustic emission (transient stress waves)
6.5 Surface Preparation—The pre-examination surface
caused by growing flaws. The instrumentation and techniques
preparation criteria shall be in accordance with 9.2 unless
for sensing and analyzing AE data are described.
otherwise specified.
4.2 This practice provides guidelines to determine the loca-
6.6 Reporting Criteria/Acceptance Criteria—Reporting cri-
tion and severity of structural flaws in FRP equipment.
teria for the examination results shall be in accordance with
4.3 ThispracticeprovidesguidelinesforAEexaminationof Section13unlessotherwisespecified.Sinceacceptancecriteria
are not specified in this practice, they shall be specified in the
FRP equipment within the pressure range stated in 1.2.
Maximum test pressure (or vacuum) for an FRPvessel will be contractual agreement.
determined upon agreement among user, manufacturer, or test
agency, or a combination thereof. Pressure vessels will nor- 7. Instrumentation
mally be tested to 1.1×operating pressure. Atmospheric stor-
7.1 The AE instrumentation consists of sensors, signal
age vessels and vacuum vessels will normally be tested under
processors, and recording equipment. Additional information
maximumoperatingconditions.Vesselswillnormallybetested
on AE instrumentation can be found in Practice E750.
at ambient temperature. In the case of elevated operating
7.2 Instrumentation shall be capable of recording AE hits,
temperature the test may be performed either at operating or
signal strength and hit duration and have sufficient channels to
ambient temperature. The test temperature must be below the
localize AE sources in real time. It may incorporate (as an
glass transition temperature of the resin.
option) peak-amplitude detection for each input channel or for
5. Significance and Use
groups of channels. Hit detection is required for each channel.
AnAE hit amplitude measurement is recommended for sensi-
5.1 The AE examination method detects damage in FRP
equipment. The damage mechanisms that are detected in FRP tivity verification (see AnnexA2).Amplitude distributions are
recommended for flaw characterization. It is preferred thatAE
are as follows: resin cracking, fiber debonding, fiber pullout,
instrumentation acquire and record duration hit and amplitude
fiber breakage, delamination, and bond failure in assembled
information on a per channel basis. TheAE instrumentation is
joints (for example, nozzles, manways, and so forth). Flaws in
further described in Annex A1.
unstressed areas and flaws that are structurally insignificant
will not generate AE.
7.3 Capability for measuring parameters such as time and
5.2 This practice is convenient for on-line use under oper- pressure shall be provided. The pressure-vacuum in the vessel
ating stress to determine structural integrity of in-service should be continuously monitored to an accuracy of 62%of
equipment usually with minimal process disruption. the maximum test value.
E1067/E1067M − 18
TABLE 1 Requirements for Reduced Operating Pressure-Load
7.4 Lockouts and Guard Sensors—These techniques shall
Immediately Prior to Examining
not be used.
% of Operating Time at Reduced
7.5 Instrument Displays—- The instrumentation shall be
Pressure or Pressure or
Load, or Both Load, or Both
capable of providing the following real time displays:
10 or less 12 h
7.5.1 Bar Chart by Channel of Cumulative Signal
20 18 h
Strength—Enables the examiner to identify which channel is
30 30 h
recording the most data.
40 2 days
50 4 days
7.5.2 Amplitude per Hit Versus Time—Provides the exam-
60 7 days
inerwithearlywarningofanimpendingfailure(seeReference
(1)).
7.5.3 Duration per Hit Versus Time—Useful for identifying
corresponding row in the second column shows the time that
rubbing or sliding (see Reference (1)).
must be spent at the reduced pressure, to condition the vessel
7.5.4 Log Duration (or Counts) per Hit Versus Amplitude
prior to making anAE test.When the percentage falls between
per Hit—Helps the examiner determine the presence of false
two values in the first column, the higher value is used.
emission signals (see Reference (1)).
8.3 Vessel Stressing—Arrangements should be made to
7.5.5 Cumulative Signal Strength per Channel Versus
stress the vessel as prescribed in 4.3. The stress rate shall be
Time—Useful for identifying certain types of instrument mal-
sufficient to expedite the examination with minimum extrane-
functions; for example, continuous electronic noise will pro-
ous noise. Holding stress levels is a key aspect of an acoustic
duce a characteristically steady rise with time, unlike the
emission examination. Accordingly, provision must be made
stepwise rise associated with natural AE.
for holding the pressure-load at designated check points.
7.6 Cumulative Amplitude Distribution, or a tabular listing
8.3.1 Atmospheric Tanks—Processliquidisthepreferredfill
by channel number of total hits equal to and greater than
medium for atmospheric tanks. If water must replace the
defined amplitude values. Tabular amplitude values shall be in
process liquid, the designer and user shall be in agreement on
increments of not greater than 5 dB and shall be for at least a
the procedure to achieve acceptable stress levels.
35dBrangebeginningatthethreshold.Thesedisplaysareused
8.3.2 Vacuum-Tank Stressing—A controllable vacuum-
toprovidewarningofsignificantfiberbreakageofthetypethat
pump system is required for vacuum tanks.
can lead to sudden structural failure.The displays also provide
8.3.3 Pressure-Vessel Stressing—Water is the preferred me-
information about the micromechanisms giving rise to the
dium for pressure tanks. Safe means for hydraulically increas-
emission and warn of potential instrument malfunction.
ing the pressure under controlled conditions shall be provided.
8.4 Tank Support—The tank shall be examined in its oper-
8. Examination Preparations
ating position and supported in a manner consistent with good
8.1 Safety—All plant safety requirements unique to the
installation practice. Flat-bottomed tanks examined in other
examination location shall be met.
than the intended location shall be mounted on a pad (for
8.1.1 Protective clothing and equipment that is normally
example, rubber on a concrete base or equivalent) to reduce
required in the area in which the examination is being
structure-borne noise between the tank and base.
conducted shall be worn.
8.5 Environmental—The normal minimum acceptable ves-
8.1.2 A fire permit may be needed to use the electronic
sel wall temperature is 4°C [40°F].
instrumentation.
8.6 Noise Reduction—Noise sources in the examination
8.1.3 Precautions shall be taken to protect against the
frequency and amplitude range, such as rain, spargers, and
consequences of catastrophic failure when pressure testing, for
foreign objects contacting the tank, must be minimized since
example, flying debris and impact of escaping liquid. Pressur-
they mask the AE signals emanating from the structure. The
izing under pneumatic conditions is not recommended except
inlet should be at the lowest nozzle or as near to the bottom of
when normal service loads include either a superposed gas
the vessel as possible, that is, below the liquid level. Liquid
pressure or gas pressure only. Care shall be taken to avoid
falling, swirling, or splashing can invalidate data obtained
overstressing the lower section of the vessel when liquid test
during the filling phase. However, this needs to be addressed
loads are used to simulate operating gas pressures.
byappropriatedatafiltering,notbyturningoffdataacquisition
8.1.4 Special safety precautions shall be taken when pneu-
during the filling phase altogether.
matic testing is required; for example, safety valves, and so
forth.
8.7 Power Supply—Astable grounded power supply, meet-
ing the specification of the instrumentation, is required at the
8.2 Vessel Conditioning—The operating conditions for ves-
examination site.
selsthathavebeenstressedpreviouslyshallbereducedpriorto
examining in accordance with the schedule shown in Table 1. 8.8 Instrumentation Settings—Settings will be determined
Table 1 is used as follows. The planned reduced pressure is
as described in Annex A2.
expressed as a percentage of the maximum operating pressure
9. Sensors
or load in the vessel during the past year (the latter must be
known in order to conduct the AE examination properly). 9.1 Sensor Mounting—RefertoPracticeE650foradditional
Looking for this percentage in the first column of Table 1, the information on sensor mounting. Location and spacing of the
E1067/E1067M − 18
sensors are discussed in 9.4. Sensors shall be placed in rings, and visible flaws. Spacings are governed by the attenu-
designated locations with a couplant between the sensor and ation of the FRP material.
examination article. One recommended couplant is silicone-
9.4.1 Attenuation Characterization—Typical signal propa-
stopcock grease. Care must be exercised to assure that ad- gation losses shall be determined in accordance with the
equate couplant is applied. Sensors shall be held in place
following procedure. This procedure provides a relative mea-
utilizingmethodsofattachmentwhichdonotcreateextraneous sure of the attenuation, but may not be representative of
signals. Methods of attachment using crossed strips of
genuineAEactivity.Itshouldbenotedthatthepeakamplitude
pressure-sensitive tape or suitable adhesive systems, may be from a mechanical pencil lead break may vary with surface
considered. Suitable adhesive systems are those whose bond-
hardness, resin condition, and cure. The attenuation character-
ing and acoustic coupling effectiveness have been demon- ization should be made above the liquid line.
strated. The attachment method should provide support for the
9.4.1.1 Select a representative region of the vessel away
signal cable (and preamplifier) to prevent the cable(s) from
frommanways,nozzles,andsoforth.MountanAEsensorand
stressing the sensor or pulling the sensor away from the
locate points at distances of 150 mm [6in.] and 300 mm
examination article causing loss of coupling.
[12in.]fromthecenterofthesensoralongalineparalleltoone
of the principal directions of the surface fiber (if applicable).
9.2 Surface Contact—Reliable coupling between the sensor
Select two additional points on the surface of the vessel at
and tank surface shall be assured and the surface of the vessel
150mm [6 in.] and 300 mm [12 in.] along a line inclined 45°
in contact with the sensor shall be clean and free of particulate
to the direction of the original points. At each of the four
matter. Sensors should be mounted directly on the tank surface
points,break0.3mm2Hleads andrecordpeakamplitude.All
unless integral waveguides shown by test to be satisfactory are
lead breaks shall be done at an angle of approximately 30° to
used. Preparation of the contact surface shall be compatible
the surface with a 2.5 mm [0.1 in.] lead extension. The data
with both sensor and structure modification requirements.
shall be retained as part of the original experimental record.
Possible causes of signal loss are coatings such as paint and
9.4.2 Sensor Spacings—The recommended sensor spacing
encapsulants, surface curvature, and surface roughness at the
onthevesselshallnotbegreaterthan3×thedistanceatwhich
contact area.
detectedsignalsfromtheattenuationcharacterizationequalthe
9.3 High-frequency and Low-frequency Channels—See An-
threshold setting.
nex A1, subsections A1.1.2 and A1.1.3 for specifications of
9.4.3 Sensor Location—Sensor location guidelines for the
high-frequency and low-frequency sensors. High-frequency
following tank types are given in theAnnex. Other tank types
channels are used with zone location for the purpose of
require an agreement among the owner, manufacturer, or
identifyingandevaluatingemissionsourcesthatmayrepresent
examination agency, or combinations thereof.
defects.All evaluation ofAE sources shall be conducted using
9.4.3.1 Case I: Atmospheric Vertical Tank—flat bottom,
high-frequency channels. Low-frequency channels can detect
flanged and dished head, typical nozzle and manway
sources over a greater distance. They may optionally be used
configuration, cylindrical shell fabricated in two sections with
on large vessels when coverage of the whole vessel with
secondary bond-butt joint, dip pipe.
high-frequency channels would be uneconomical. When both
9.4.3.2 Case II: Atmospheric Vertical Tank—flatbottom,2:1
kinds of sensor are used, high-frequency sensors are placed to
elliptical head, typical nozzle and manway configuration,
cover the higher-risk/higher-stress regions of the vessel (for
agitatorwithbaffles,cylindricalshellfabricatedinonesection.
example, shell to base transition, manways, nozzles). Low-
9.4.3.3 Case III: Atmospheric-Pressure Vertical Tank—
frequency sensors are placed in lower-risk regions (for
flanged and dished heads top and bottom, typical nozzle and
example, shell sections remote from structural discontinuities)
manway configuration, packing support, legs attached to cy-
where there is a lower probability of active AE sources being
lindrical shell, cylindrical shell fabricated in one section.
present. If significant activity detected on low-frequency chan-
nels is not detected simultaneously on high-frequency 9.4.3.4 Case IV: Atmospheric-Pressure Vertical Tank—cone
bottom, 2:1 elliptical head, typical nozzle and manway
channels, the adequacy of high-frequency sensor location shall
be assessed by the examiner. High-frequency channels may be configuration,cylindricalshellfabricatedintwosections,body
flange, dip pipe, support ring.
addedorrelocatedandloadingrepeatedafterreconditioningof
the vessel, as necessary, for conclusive examination of the
9.4.3.5 Case V: Atmospheric-Vacuum Vertical Tank—
emissiveareasindicatedbythelow-frequencychannels.Inthis flanged and dished heads top and bottom, typical nozzle and
manner, the low-frequency channels are used to ensure ad-
manway configuration, packing support, stiffening ribs, sup-
equacy of the vessel coverage by high-frequency channels. port ring, cylindrical shell fabricated in two sections with
Caution should be exercised in the use of low-frequency
secondary bond-butt joint.
sensors, considering the adequacy of vessel coverage for final
9.4.3.6 Case VI: Atmospheric-Pressure Horizontal Tank—
evaluation, and considering that low-frequency channels are
flanged and dished heads, typical nozzle and manway
more vulnerable to background noise, waves travelling across
configuration, cylindrical shell fabricated in two sections with
the liquid from remote locations, and so forth.
secondary bond-butt joint, saddle supports.
9.4 Locations and Spacings—Locations on the vessel shell
are determined by the need to detect structural flaws at critical
sections; for example, high-stress areas, geometric
Pentel 0.3-mm (2H) lead or its equivalent has been found satisfactory for this
discontinuities, nozzles, manways, repaired regions, support purpose.
E1067/E1067M − 18
10. Instrumentation System Performance Check Sources of background noise include the following: liquid
splashingintoatank,afillratethatistoohigh,pumps,motors,
10.1 Sensor Coupling and Circuit Continuity Verification—
agitators and other mechanical devices, electromagnetic
Verification shall be performed following sensor mounting and
interference,andenvironmentalfactors,suchasrain,wind,and
system setup. The response of each sensor-preamplifier com-
so forth.
binationtoarepeatablesimulatedacousticemissionsource(for
example, pencil lead break) shall be recorded and evaluated 11.2 Loading—Atmospheric tanks that operate with liquid
head and superimposed pressures of 0.2 MPa [30 psia, 2 bars]
prior to the examination (see Guide E2374).
or less, and vacuum vessels that operate at pressures below
10.1.1 The peak amplitude of the simulated event at a
atmospheric,shallbeloadedinaseriesofsteps.Recommended
specific distance from each sensor should not vary more than
load procedures are shown in Fig. 1 and Fig. 2. The algorithm
6dB from the average of all the sensors. Any sensor-
flow chart for this class of tanks is given in Fig. 3.
preamplifier combination failing this check should be investi-
11.2.1 For tanks that have been stressed previously, the
gated and replaced or repaired as necessary.
examination can begin with the liquid level as high as 60% of
10.1.2 After the initial condition of each installed channel
theoperatingormaximumtestlevel(see8.2).Fig.1shouldbe
has been verified as satisfactory per the preceding paragraphs,
modifiedforvesselsthatarepartiallyfullatthebeginningofan
a global check such as automatic sensor test (AST) should be
examination. The background noise baseline determination is
performed to furnish a baseline for whatever post test and
important for this class of examination and should be provided
interim checks are planned (see 10.3). AST, though less
for. Many vessels operate with liquid contents and partial
comprehensive than pencil lead break technique, takes much
vacuum; however, vacuum vessels are normally examined
less time to perform.
empty.
10.2 Background Noise Check—A background noise check
11.2.2 Pressure vessels that operate with superimposed
isrecommendedtoidentifyanddeterminethelevelofspurious
pressures greater than 0.2 MPa [30 psia] shall be loaded in a
signals. This is done following the completion of the verifica-
series of pressurize-and-hold, depressurize-and-hold steps as
tion described in 10.1 and prior to stressing the vessel. A
shown in Fig. 4. The depressurize-and-hold steps in this
recommended time period is 20 minutes.
schedulemaybeeliminatedifnoemissionhasbeendetectedin
10.3 Post Test and Interim Checks—Aftercompletionofthe
the previous pressurize-and-hold steps. Prior to loading, pres-
loading/monitoring, a check should be conducted to verify the
sure vessels shall be conditioned as described in 8.2.AE
stability of channel performance, in particular the continuing
monitoring of the first loading of new pressure vessels is
integrity of sensor mounting and coupling. This can be
optional, since they may be too noisy to meet the acceptance
accomplished by repeating a global check such as AST, see
criteria;however,firstloadingdatacanhavevalueasabaseline
10.1.2. Interim tests of this kind can also be employed in
andindicatoroflong-termperformance.Incaseanewvesselis
unusualsituationssuchaslengthytestinterruptions,toconfirm
notmonitoredduringitsfirstloading,orincaseitismonitored
the ongoing integrity of the monitoring setup. In the event that
and does not meet the evaluation criteria, then it is recondi-
these tests show one or more channels to have become
tioned in accordance with 8.2, reloaded with AE monitoring
ineffective, corrective measures shall be taken and/or consid-
and evaluated against the “subsequent loading” criteria (see
eration shall be given to the status of the affected zone(s)
Table X1.2). The algorithm flow chart for this class of tanks is
relative to the goal
...

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: E1067/E1067M − 11 E1067/E1067M − 18
Standard Practice for
Acoustic Emission Examination of Fiberglass Reinforced
Plastic Resin (FRP) Tanks/Vessels
This standard is issued under the fixed designation E1067/E1067M; 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 acoustic emission (AE) examination or monitoring of fiberglass-reinforced plastic (FRP) tanks-vessels
(equipment) under pressure or vacuum to determine structural integrity.
1.2 This practice is limited to tanks-vessels designed to operate at an internal pressure no greater than 1.73 MPa absolute [250
psia] psia, 17.3 bar] above the static pressure due to the internal contents. It is also applicable for tanks-vessels designed for
vacuum service with differential pressure levels between 0 and 0.10 MPa [0 and 14.5 psi].psi, 1 bar].
1.3 This practice is limited to tanks-vessels with glass contents greater than 15 % by weight.
1.4 This practice applies to examinations of new and in-service equipment.
1.5 Units—The values stated in either SI units or inch-pound units are to be regarded 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.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.(For more specific safety precautionary information see 8.1.)
1.7 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:
D883 Terminology Relating to Plastics
D5436 Specification for Cast Poly(Methyl Methacrylate) Plastic Rods, Tubes, and Shapes
E543 Specification for Agencies Performing Nondestructive Testing
E650 Guide for Mounting Piezoelectric Acoustic Emission Sensors
E750 Practice for Characterizing Acoustic Emission Instrumentation
E1106 Test Method for Primary Calibration of Acoustic Emission Sensors
E1316 Terminology for Nondestructive Examinations
E2075 Practice for Verifying the Consistency of AE-Sensor Response Using an Acrylic Rod
E1781 Practice for Secondary Calibration of Acoustic Emission Sensors
E2374 Guide for Acoustic Emission System Performance Verification
2.2 ANSI/ASNT Standards:
SNT-TC-1A Recommended Practice for Nondestructive Testing Personnel Qualification and Certification
ANSI/ASNT CP-189 Standard for Qualification and Certification of Nondestructive Testing Personnel
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 July 1, 2011Feb. 1, 2018. Published July 2011February 2018. Originally approved in 1985. Last previous edition approved in 20072011 as
E1067 - 07.E1067/E1067M – 11. DOI: 10.1520/E1067-11.10.1520/E1067-18.
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.
Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.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
E1067/E1067M − 18
2.3 AIA Standard:
NAS-410 Certification and Qualification of Nondestructive Personnel (Quality Assurance Committee)
2.4 ISO Standard:
ISO 9712 Non-Destructive Testing—Qualification and Certification of NDT Personnel
3. Terminology
3.1 Complete definitions of terms related to plastics and acoustic emission will be found in Terminology D883 and E1316.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 FRP—fiberglass reinforced plastic, a glass-fiber polymer composite with certain mechanical properties superior to those
of the base resin.
3.2.2 operating pressure—the pressure at the top of a vessel at which it normally operates. It shall not exceed the design pressure
and it is usually kept at a suitable level below the setting of the pressure-relieving devices to prevent their frequent opening.
3.2.3 pressure, design—the pressure used in design to determine the required minimum thicknesses and minimum mechanical
properties.
3.2.4 processor—a circuit that analyzes AE waveforms. (See Section 7 and A1.8.)
3.2.5 summing amplifier (summer, mixer)—an operational amplifier that produces an output signal equal to a weighted sum of
the input signals.
3.2.6 zone—the area surrounding a sensor from which AE can be detected by that sensor.
4. Summary of Practice
4.1 This practice consists of subjecting equipment to increasing pressure or vacuum while monitoring with sensors that are
sensitive to acoustic emission (transient stress waves) caused by growing flaws. The instrumentation and techniques for sensing
and analyzing AE data are described.
4.2 This practice provides guidelines to determine the location and severity of structural flaws in FRP equipment.
4.3 This practice provides guidelines for AE examination of FRP equipment within the pressure range stated in 1.2. Maximum
test pressure (or vacuum) for an FRP vessel will be determined upon agreement among user, manufacturer, or test agency, or a
combination thereof. Pressure vessels will normally be tested to 1.1 × operating pressure. Atmospheric storage vessels and vacuum
vessels will normally be tested under maximum operating conditions. Vessels will normally be tested at ambient temperature. In
the case of elevated operating temperature the test may be performed either at operating or ambient temperature. The test
temperature must be below the glass transition temperature of the resin.
5. Significance and Use
5.1 The AE examination method detects damage in FRP equipment. The damage mechanisms that are detected in FRP are as
follows: resin cracking, fiber debonding, fiber pullout, fiber breakage, delamination, and bond failure in assembled joints (for
example, nozzles, manways, etc.). and so forth). Flaws in unstressed areas and flaws that are structurally insignificant will not
generate AE.
5.2 This practice is convenient for on-line use under operating stress to determine structural integrity of in-service equipment
usually with minimal process disruption.
5.3 Indications located with AE should be examined by other techniques; for example, visual, ultrasound, dye penetrant, etc.,
and and so forth, and may be repaired and tested as appropriate. Repair procedure recommendations are outside the scope of this
practice.
6. Basis of Application
6.1 The following items are subject to contractual agreement between the parties using or referencing this practice:
6.2 Personnel Qualification:
6.2.1 If specified in the contractual agreement, personnel performing examinations to this standard 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.
6.3 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.
6.4 Procedures and Techniques—The procedures and techniques to be utilized shall be as specified in the contractual agreement.
Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http://www.aia-aerospace.org.
E1067/E1067M − 18
6.5 Surface Preparation—The pre-examination surface preparation criteria shall be in accordance with 9.2 unless otherwise
specified.
6.6 Reporting Criteria/Acceptance Criteria—Reporting criteria for the examination results shall be in accordance with Section
13 unless otherwise specified. Since acceptance criteria are not specified in this practice, they shall be specified in the contractual
agreement.
7. Instrumentation
7.1 The AE instrumentation consists of sensors, signal processors, and recording equipment. Additional information on AE
instrumentation can be found in Practice E750.
7.2 Instrumentation shall be capable of recording AE hits, signal strength and hit duration and have sufficient channels to
localize AE sources in real time. It may incorporate (as an option) peak-amplitude detection for each input channel or for groups
of channels. Hit detection is required for each channel. An AE hit amplitude measurement is recommended for sensitivity
verification (see Annex A2). Amplitude distributions are recommended for flaw characterization. It is preferred that AE
instrumentation acquire and record duration hit and amplitude information on a per channel basis. The AE instrumentation is
further described in Annex A1.
7.3 Capability for measuring parameters such as time and pressure shall be provided. The pressure-vacuum in the vessel should
be continuously monitored to an accuracy of 62 % of the maximum test value.
7.4 Lockouts and Guard Sensors—These techniques shall not be used.
7.5 Instrument Displays—- The instrumentation shall be capable of providing the following real time displays:
7.5.1 Bar Chart by Channel of Cumulative Signal Strength—Enables the inspectorexaminer to identify which channel is
recording the most data.
7.5.2 Amplitude per Hit Versus Time—Provides the inspectorexaminer with early warning of an impending failure.failure (see
Reference (1)).
7.5.3 Duration per Hit Versus Time—Useful for identifying rubbing or sliding.sliding (see Reference (1)).
7.5.4 Log Duration (or Counts) per Hit Versus Amplitude per Hit—Helps the inspectorexaminer determine the presence of false
emission signals (see Reference (1)).
7.5.5 Cumulative Signal Strength per Channel Versus Time—Useful for identifying certain types of instrument malfunctions-
.malfunctions; for example, continuous electronic noise will produce a characteristically steady rise with time, unlike the stepwise
rise associated with natural AE.
7.6 Cumulative Amplitude Distribution, or a tabular listing by channel number of total hits equal to and greater than defined
amplitude values. Tabular amplitude values shall be in increments of not greater than 5 dB and shall be for at least a 35 dB range
beginning at the threshold. These displays are used to provide warning of significant fiber breakage of the type that can lead to
sudden structural failure. The displays also provide information about the micromechanisms giving rise to the emission and warn
of potential instrument malfunction.
8. Examination Preparations
8.1 Safety—All plant safety requirements unique to the examination location shall be met.
8.1.1 Protective clothing and equipment that is normally required in the area in which the examination is being conducted shall
be worn.
8.1.2 A fire permit may be needed to use the electronic instrumentation.
8.1.3 Precautions shall be taken to protect against the consequences of catastrophic failure when pressure testing, for example,
flying debris and impact of escaping liquid. Pressurizing under pneumatic conditions is not recommended except when normal
service loads include either a superposed gas pressure or gas pressure only. Care shall be taken to avoid overstressing the lower
section of the vessel when liquid test loads are used to simulate operating gas pressures.
8.1.4 Special safety precautions shall be taken when pneumatic testing is required; for example, safety valves, etc.and so forth.
8.2 Vessel Conditioning—The operating conditions for vessels that have been stressed previously shall be reduced prior to
examining in accordance with the schedule shown in Table 1. Table 1The is used as follows. The planned reduced pressure is
expressed as a percentage of the maximum operating pressure or load in the vessel during the past year (the latter must be known
in order to conduct the AE examination properly.properly). Looking for this percentage in the first column of Table 1, the
corresponding row in the second column shows the time that must be spent at the reduced pressure, to condition the vessel prior
to making an AE test. When the percentage falls between two values in the first column, the higher value is used.
8.3 Vessel Stressing—Arrangements should be made to stress the vessel to the operatingas prescribed in 4.3pressure-load where
possible. . The stress rate shall be sufficient to expedite the examination with minimum extraneous noise. Holding stress levels is
a key aspect of an acoustic emission examination. Accordingly, provision must be made for holding the pressure-load at designated
check points.
E1067/E1067M − 18
TABLE 1 Requirements for Reduced Operating Pressure-Load
Immediately Prior to Examining
% of Operating Time at Reduced
Pressure or Pressure or
Load, or Both Load, or Both
10 or less 12 h
20 18 h
30 30 h
40 2 days
50 4 days
60 7 days
8.3.1 Atmospheric Tanks—Process liquid is the preferred fill medium for atmospheric tanks. If water must replace the process
liquid, the designer and user shall be in agreement on the procedure to achieve acceptable stress levels.
8.3.2 Vacuum-Tank Stressing—A controllable vacuum-pump system is required for vacuum tanks.
8.3.3 Pressure-Vessel Stressing—Water is the preferred medium for pressure tanks. Safe means for hydraulically increasing the
pressure under controlled conditions shall be provided.
8.4 Tank Support—The tank shall be examined in its operating position and supported in a manner consistent with good
installation practice. Flat-bottomed tanks examined in other than the intended location shall be mounted on a pad (for example,
rubber on a concrete base or equivalent) to reduce structure-borne noise between the tank and base.
8.5 Environmental—The normal minimum acceptable vessel wall temperature is 4°C [40°F].
8.6 Noise Reduction—Noise sources in the examination frequency and amplitude range, such as rain, spargers, and foreign
objects contacting the tank, must be minimized since they mask the AE signals emanating from the structure. The inlet should be
at the lowest nozzle or as near to the bottom of the vessel as possible, that is, below the liquid level. Liquid falling, swirling, or
splashing can invalidate data obtained during the filling phase. However, this needs to be addressed by appropriate data filtering,
not by turning off data acquisition during the filling phase altogether.
8.7 Power Supply—A stable grounded power supply, meeting the specification of the instrumentation, is required at the
examination site.
8.8 Instrumentation Settings—Settings will be determined as described in Annex A2.
9. Sensors
9.1 Sensor Mounting—Refer to Practice E650 for additional information on sensor mounting. Location and spacing of the
sensors are discussed in 9.39.4. Sensors shall be placed in designated locations with a couplant between the sensor and examination
article. One recommended couplant is silicone-stopcock grease. Care must be exercised to assure that adequate couplant is applied.
Sensors shall be held in place utilizing methods of attachment which do not create extraneous signals. Methods of attachment using
crossed strips of pressure-sensitive tape or suitable adhesive systems, may be considered. Suitable adhesive systems are those
whose bonding and acoustic coupling effectiveness have been demonstrated. The attachment method should provide support for
the signal cable (and preamplifier) to prevent the cable(s) from stressing the sensor or pulling the sensor away from the examination
article causing loss of coupling.
9.2 Surface Contact—Reliable coupling between the sensor and tank surface shall be assured and the surface of the vessel in
contact with the sensor shall be clean and free of particulate matter. Sensors should be mounted directly on the tank surface unless
integral waveguides shown by test to be satisfactory are used. Preparation of the contact surface shall be compatible with both
sensor and structure modification requirements. Possible causes of signal loss are coatings such as paint and encapsulants, surface
curvature, and surface roughness at the contact area.
9.3 High-frequency and Low-frequency Channels—See Annex A1, subsections A1.1.2 and A1.1.3 for specifications of
high-frequency and low-frequency sensors. High-frequency channels are used with zone location for the purpose of identifying and
evaluating emission sources that may represent defects. All evaluation of AE sources shall be conducted using high-frequency
channels. Low-frequency channels can detect sources over a greater distance. They may optionally be used on large vessels when
coverage of the whole vessel with high-frequency channels would be uneconomical. When both kinds of sensor are used,
high-frequency sensors are placed to cover the higher-risk/higher-stress regions of the vessel (for example, shell to base transition,
manways, nozzles). Low-frequency sensors are placed in lower-risk regions (for example, shell sections remote from structural
discontinuities) where there is a lower probability of active AE sources being present. If significant activity detected on
low-frequency channels is not detected simultaneously on high-frequency channels, the adequacy of high-frequency sensor
location shall be assessed by the examiner. High-frequency channels may be added or relocated and loading repeated after
reconditioning of the vessel, as necessary, for conclusive examination of the emissive areas indicated by the low-frequency
channels. In this manner, the low-frequency channels are used to ensure adequacy of the vessel coverage by high-frequency
E1067/E1067M − 18
channels. Caution should be exercised in the use of low-frequency sensors, considering the adequacy of vessel coverage for final
evaluation, and considering that low-frequency channels are more vulnerable to background noise, waves travelling across the
liquid from remote locations, and so forth.
9.4 Locations and Spacings—Locations on the vessel shell are determined by the need to detect structural flaws at critical
sections; for example, high-stress areas, geometric discontinuities, nozzles, manways, repaired regions, support rings, and visible
flaws. Spacings are governed by the attenuation of the FRP material.
9.4.1 Attenuation Characterization—Typical signal propagation losses shall be determined in accordance with the following
procedure. This procedure provides a relative measure of the attenuation, but may not be representative of genuine AE activity.
It should be noted that the peak amplitude from a mechanical pencil lead break may vary with surface hardness, resin condition,
and cure. The attenuation characterization should be made above the liquid line.
9.4.1.1 Select a representative region of the vessel away from manways, nozzles, etc. and so forth. Mount an AE sensor and
locate points at distances of 150 mm [6 in.] [6 in.] and 300 mm [12 in.] [12 in.] from the center of the sensor along a line parallel
to one of the principal directions of the surface fiber (if applicable). Select two additional points on the surface of the vessel at
150 mm 150 mm [6 in.] and 300 mm [12 in.] along a line inclined 45° to the direction of the original points. At each of the four
points, break 0.3 mm 2H leads and record peak amplitude. All lead breaks shall be done at an angle of approximately 30° to the
surface with a 2.5 mm [0.1 in.] lead extension. The data shall be retained as part of the original experimental record.
9.4.2 Sensor Spacings—The recommended sensor spacing on the vessel shall not be greater than 3 × the distance at which
detected signals from the attenuation characterization equal the threshold setting.
9.4.3 Sensor Location—Sensor location guidelines for the following tank types are given in the Annex. Other tank types require
an agreement among the owner, manufacturer, or examination agency, or combinations thereof.
9.4.3.1 Case I: Atmospheric Vertical Tank—flat bottom, flanged and dished head, typical nozzle and manway configuration,
cylindrical shell fabricated in two sections with secondary bond-butt joint, dip pipe.
9.4.3.2 Case II: Atmospheric Vertical Tank—flat bottom, 2:1 elliptical head, typical nozzle and manway configuration, agitator
with baffles, cylindrical shell fabricated in one section.
9.4.3.3 Case III: Atmospheric-Pressure Vertical Tank—flanged and dished heads top and bottom, typical nozzle and manway
configuration, packing support, legs attached to cylindrical shell, cylindrical shell fabricated in one section.
9.4.3.4 Case IV: Atmospheric-Pressure Vertical Tank—cone bottom, 2:1 elliptical head, typical nozzle and manway
configuration, cylindrical shell fabricated in two sections, body flange, dip pipe, support ring.
9.4.3.5 Case V: Atmospheric-Vacuum Vertical Tank—flanged and dished heads top and bottom, typical nozzle and manway
configuration, packing support, stiffening ribs, support ring, cylindrical shell fabricated in two sections with secondary bond-butt
joint.
9.4.3.6 Case VI: Atmospheric-Pressure Horizontal Tank—flanged and dished heads, typical nozzle and manway configuration,
cylindrical shell fabricated in two sections with secondary bond-butt joint, saddle supports.
10. Instrumentation System Performance Check
10.1 Sensor Coupling and Circuit Continuity Verification—Verification shall be performed following sensor mounting and
system setup. The response of each sensor-preamplifier combination to a repeatable simulated acoustic emission source should (for
example, pencil lead break) shall be recorded and evaluated prior to the examination (see Guide E2374).
10.1.1 The peak amplitude of the simulated event at a specific distance from each sensor should not vary more than 6 dB 6 dB
from the average of all the sensors. Any sensor-preamplifier combination failing this check should be investigated and replaced
or repaired as necessary.
10.1.2 After the initial condition of each installed channel has been verified as satisfactory per the preceding paragraphs, a
global check such as automatic sensor test (AST) should be performed to furnish a baseline for whatever post test and interim
checks are planned (see 10.3). AST, though less comprehensive than pencil lead break technique, takes much less time to perform.
10.2 Background Noise Check—A background noise check is recommended to identify and determine the level of spurious
signals. This is done following the completion of the verification described in 10.1 and prior to stressing the vessel. A
recommended time period is 20 minutes.
10.3 Post Test and Interim Checks—After completion of the loading/monitoring, a check should be conducted to verify the
stability of channel performance, in particular the continuing integrity of sensor mounting and coupling. This can be accomplished
by repeating a global check such as AST, see 10.1.2. Interim tests of this kind can also be employed in unusual situations such
as lengthy test interruptions, to confirm the ongoing integrity of the monitoring setup. In the event that these tests show one or more
channels to have become ineffective, corrective measures shall be taken and/or consideration shall be given to the status of the
affected zone(s) relative to the goals of the inspection.
Pentel 0.3-mm (2H) lead or its equivalent has been found satisfactory for this purpose.
E1067/E1067M − 18
11. Examination Procedure
11.1 General Guidelines—The tank-vessel is subjected to programmed increasing pressure-load levels to a predetermined
maximum while being monitored by sensors that detect acoustic emission (stress waves) caused by growing structural flaws.
11.1.1 Fill and pressurization rates shall be controlled so as not to exceed a strain rate of 0.005 %⁄min per min based on
calculated values or actual strain gage measurements of principal strains. Normally, the desired pressure will be attained with a
liquid (see 8.1.3 and 8.1.4). Pressurization with a gas (air, N etc.) and so forth) is not recommended. A suitable manometer or other
type gage shall be used to monitor pressure.
11.1.2 Vacuum should be attained with a suitable vacuum source. A quick release valve shall be provided to handle any
imminent catastrophic failure condition.
11.1.3 Background noise shall be minimized and identified (see also 8.6). Excessive background noise is cause for suspension
of the pressurization. In the analysis of examination results, background noise should be properly discounted. Sources of
background noise include the following: liquid splashing into a tank, a fill rate that is too high, pumps, motors, agitators and other
mechanical devices, electromagnetic interference, and environmental factors, such as rain, wind, etc.and so forth.
11.2 Loading—Atmospheric tanks that operate with liquid head and superimposed pressures of 0.2 MPa [30 psia] psia, 2 bars]
or less, and vacuum vessels that operate at pressures below atmospheric, shall be loaded in a series of steps. Recommended load
procedures are shown in Fig. 1 and Fig. 2. The algorithm flow chart for this class of tanks is given in Fig. 3.
11.2.1 For tanks that have been stressed previously, the examination can begin with the liquid level as high as 60 % of the
operating or maximum test level (see 8.2). Fig. 1 should be modified for vessels that are partially full at the beginning of an
examination. The background noise baseline determination is important for this class of examination and should be provided for.
Many vessels operate with liquid contents and partial vacuum; however, vacuum vessels are normally examined empty.
11.2.2 Pressure vessels that operate with superimposed pressures greater than 0.2 MPa [30 psia] shall be loaded in a series of
pressurize-and-hold, depressurize-and-hold steps as shown in Fig. 4. The depressurize-and-hold steps in this schedule may be
eliminated if no emission has been detected in the previous pressurize-and-hold steps. Prior to loading, pressure vessels shall be
conditioned as described in 8.2. AE monitoring of the first loading of new pressure vessels is optional, since they may be too noisy
to meet the acceptance criteria; however, first loading data can have value as a baseline and indicator of long-term performance.
In case a new vessel is not monitored during its first loading, or in case it is monitored and does not meet the evaluation criteria,
then it is reconditioned in accordance with 8.2, reloaded with AE monitoring and evaluated against the “subsequent loading”
criteria (see Table X1.2). The algorithm flow chart for this class of tanks is given in Fig. 5.
11.2.3 The initial hold period is used to determine a baseline of the background noise. This data provides an estimate of the total
background noise contribution during the examination. Background noise shall be discounted in the final data analysis.
FIG. 1 Atmospheric Tank Examination, Stressing Sequence
E1067/E1067M − 18
FIG. 2 Vacuum Tank Examination, Stressing Sequence
FIG. 3 AE Examination Algorithm—Flow Chart Atmospheric-Vacuum Tanks (See Fig. 1 and Fig. 2.)
11.2.4 Intermittent load holds shall be for 4 min. As shown in Fig. 4, pressure vessels shall be loaded in steps up to 30 % of
the maximum test pressure. Thereafter, the pressure shall be decreased by 10 % of the maximum test pressure before proceeding
to the next hold level. Following
...