ASTM E2907/E2907M-13(2019)
(Practice)Standard Practice for Examination of Paper Machine Rolls Using Acoustic Emission from Crack Face Rubbing
Standard Practice for Examination of Paper Machine Rolls Using Acoustic Emission from Crack Face Rubbing
SIGNIFICANCE AND USE
5.1 Paper machine rolls can range in size from 2.4 to 9 m [8 to 30 ft] long, with a shell thickness of from 12.5 to 75 mm [0.5 to 3 in.,] and 300 to 1200 mm [12 to 48 in.] diameter. Depending on purpose, paper machine rolls can weigh as little as 60 000 kg [13 000 lb] to as much as 27 500 kg [60 000 lb].
5.2 If indications are found during this procedure it can be repeated, with additional sensors to refine source location accuracy.
5.3 Removal of rolls for traditional NDT examination may be impractical and may not be sensitive enough to locate small defects.
5.4 Traditional AE examination, whereby the roll is subjected to load greater than service load to detect crack extension, risks damage to the roll and is best employed as a follow-up NDT examination.
5.5 Manual rotation through a full revolution subjects existing cracks to tensile and compressive forces which can open and close existing cracks, and cause friction at the crack surfaces.
5.6 Excess background noise (overhead cranes, nearby maintenance activities) may distort AE data or render it useless. Users must be aware of the following common sources of background noise: bearing noise (lack of lubrication, spalling, and so forth), mechanical contact with the roll by other objects, electromagnetic interference (EMI) and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources. This practice should not be used if background noise cannot be eliminated or controlled.
5.7 Other Non-destructive test methods may be used to evaluate the significance of AE indications. Traditional AE has been used to confirm the existence of the AE indication and fine tune the location. Magnetic particle, ultrasonic and radiographic examinations have been used to establish the position, depth and dimensions of the indication. Procedures for using other NDT methods are beyond the scope of this practice.
SCOPE
1.1 This practice provides guidelines for acoustic emission (AE) examinations of non-pressure, paper machine rolls.
1.2 This practice utilizes a slow rotation of the roll to produce a full load cycle where load is provided by the weight of the roll suspended from its bearings or other journal support mechanism(s).
1.3 This practice is used for detection of cracks and other discontinuities in rolls that produce frictional acoustic emission during rotation.
1.4 The AE measurements are used to detect or locate emission sources, or both. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1.
Note 1: Traditional AE examination, magnetic particle examination, shear wave ultrasonic examination, and radiography are commonly used to establish the exact position and dimensions of flaws that produce AE.
1.5 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.
1.6 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. Specific precautionary statements are given in Section 8.
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
- 30-Apr-2019
- Technical Committee
- E07 - Nondestructive Testing
- Drafting Committee
- E07.04 - Acoustic Emission Method
Relations
- Effective Date
- 01-May-2019
- Effective Date
- 01-Feb-2024
- Effective Date
- 01-Dec-2019
- Effective Date
- 01-Mar-2019
- Effective Date
- 01-Jan-2018
- Effective Date
- 15-Jun-2017
- Effective Date
- 01-Feb-2017
- Effective Date
- 01-Aug-2016
- Effective Date
- 01-Feb-2016
- Effective Date
- 01-Dec-2015
- Effective Date
- 01-Dec-2015
- Effective Date
- 01-Sep-2015
- Effective Date
- 01-Jun-2014
- Effective Date
- 01-Jun-2014
- Effective Date
- 01-Dec-2013
Overview
ASTM E2907/E2907M-13(2019) is the recognized international standard practice for the examination of paper machine rolls using acoustic emission (AE) generated by crack face rubbing. Developed by ASTM, this standard outlines a reliable and efficient nondestructive testing (NDT) method specifically tailored for non-pressure paper machine rolls. The technique is particularly useful for identifying cracks and discontinuities without the need to remove heavy or unwieldy rolls from service, minimizing downtime and maximizing safety and productivity in paper mills.
Key Topics
- Acoustic Emission (AE) Testing: This standard defines guidelines for using AE sensors to detect frictional sound waves produced by crack surfaces as rolls are rotated. It utilizes slow, controlled rotation to simulate a full load cycle, relying on the roll’s own weight suspended from bearings.
- Crack Face Rubbing: AE is detected from the micro-friction events at crack faces as they open and close during rotation, allowing early identification of existing flaws or developing damage.
- Nondestructive Evaluation: While AE identifies and locates emission sources, further NDT methods such as magnetic particle testing, ultrasonic testing, or radiography are required to evaluate the severity and dimensions of detected indications.
- Operational Considerations: The procedure highlights the importance of eliminating background noise (from cranes, mechanical contact, electromagnetic and radio interference) to ensure test validity. The presence of excess noise can distort or invalidate AE data.
- Safety and Standardization: The standard mandates strict adherence to safety, health, and environmental practices and emphasizes personnel qualification and certification to recognized NDT guidelines.
Applications
The ASTM E2907/E2907M standard practice offers considerable value in the pulp and paper industry:
- Maintenance of Paper Machine Rolls: Applicable to a broad range of roll sizes-from 2.4 to 9 m (8 to 30 ft) in length and weighing up to 27,500 kg (60,000 lb)-the standard allows in-situ assessment, reducing the logistical and safety challenges associated with roll removal.
- Early Detection of Defects: The method is sensitive to small cracks and defects that are difficult to locate with traditional NDT techniques, helping to prevent catastrophic failures and costly downtime.
- Routine and Follow-Up Inspections: AE examinations can be used for initial screenings, while more conventional methods serve as secondary or confirmatory tests when AE indications are found.
- Quality Assurance: Supports ongoing condition monitoring and quality control of high-value assets in continuous operation facilities, contributing to longer service life and reduced repair costs.
Related Standards
Several other ASTM and international standards complement or support the use of AE testing per ASTM E2907/E2907M:
- ASTM E543: Specification for agencies performing nondestructive testing, ensuring competence and reliability in NDT operations.
- ASTM E650: Guide for mounting piezoelectric acoustic emission sensors, focusing on proper sensor installation.
- ASTM E1316: Terminology for nondestructive examinations, providing standard definitions for consistent communication.
- ASTM E2075, E2374, E976: Guides for verifying sensor response and AE system performance, crucial for data accuracy and validation.
- ASTM E2598: Practice for AE examination of cast iron Yankee and steam-heated paper dryers, a related application in paper manufacturing.
- ASNT SNT-TC-1A and ANSI/ASNT CP-189: Standards for qualification and certification of NDT personnel.
- NAS-410: Certification for NDT personnel in the aerospace sector, referenced for personnel qualification.
Keywords: Acoustic emission testing, paper machine rolls, nondestructive testing (NDT), crack detection, AE sensors, roll inspection, ASTM E2907, industrial maintenance, pulp and paper industry.
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Frequently Asked Questions
ASTM E2907/E2907M-13(2019) is a standard published by ASTM International. Its full title is "Standard Practice for Examination of Paper Machine Rolls Using Acoustic Emission from Crack Face Rubbing". This standard covers: SIGNIFICANCE AND USE 5.1 Paper machine rolls can range in size from 2.4 to 9 m [8 to 30 ft] long, with a shell thickness of from 12.5 to 75 mm [0.5 to 3 in.,] and 300 to 1200 mm [12 to 48 in.] diameter. Depending on purpose, paper machine rolls can weigh as little as 60 000 kg [13 000 lb] to as much as 27 500 kg [60 000 lb]. 5.2 If indications are found during this procedure it can be repeated, with additional sensors to refine source location accuracy. 5.3 Removal of rolls for traditional NDT examination may be impractical and may not be sensitive enough to locate small defects. 5.4 Traditional AE examination, whereby the roll is subjected to load greater than service load to detect crack extension, risks damage to the roll and is best employed as a follow-up NDT examination. 5.5 Manual rotation through a full revolution subjects existing cracks to tensile and compressive forces which can open and close existing cracks, and cause friction at the crack surfaces. 5.6 Excess background noise (overhead cranes, nearby maintenance activities) may distort AE data or render it useless. Users must be aware of the following common sources of background noise: bearing noise (lack of lubrication, spalling, and so forth), mechanical contact with the roll by other objects, electromagnetic interference (EMI) and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources. This practice should not be used if background noise cannot be eliminated or controlled. 5.7 Other Non-destructive test methods may be used to evaluate the significance of AE indications. Traditional AE has been used to confirm the existence of the AE indication and fine tune the location. Magnetic particle, ultrasonic and radiographic examinations have been used to establish the position, depth and dimensions of the indication. Procedures for using other NDT methods are beyond the scope of this practice. SCOPE 1.1 This practice provides guidelines for acoustic emission (AE) examinations of non-pressure, paper machine rolls. 1.2 This practice utilizes a slow rotation of the roll to produce a full load cycle where load is provided by the weight of the roll suspended from its bearings or other journal support mechanism(s). 1.3 This practice is used for detection of cracks and other discontinuities in rolls that produce frictional acoustic emission during rotation. 1.4 The AE measurements are used to detect or locate emission sources, or both. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1. Note 1: Traditional AE examination, magnetic particle examination, shear wave ultrasonic examination, and radiography are commonly used to establish the exact position and dimensions of flaws that produce AE. 1.5 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. 1.6 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. Specific precautionary statements are given in Section 8. 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.
SIGNIFICANCE AND USE 5.1 Paper machine rolls can range in size from 2.4 to 9 m [8 to 30 ft] long, with a shell thickness of from 12.5 to 75 mm [0.5 to 3 in.,] and 300 to 1200 mm [12 to 48 in.] diameter. Depending on purpose, paper machine rolls can weigh as little as 60 000 kg [13 000 lb] to as much as 27 500 kg [60 000 lb]. 5.2 If indications are found during this procedure it can be repeated, with additional sensors to refine source location accuracy. 5.3 Removal of rolls for traditional NDT examination may be impractical and may not be sensitive enough to locate small defects. 5.4 Traditional AE examination, whereby the roll is subjected to load greater than service load to detect crack extension, risks damage to the roll and is best employed as a follow-up NDT examination. 5.5 Manual rotation through a full revolution subjects existing cracks to tensile and compressive forces which can open and close existing cracks, and cause friction at the crack surfaces. 5.6 Excess background noise (overhead cranes, nearby maintenance activities) may distort AE data or render it useless. Users must be aware of the following common sources of background noise: bearing noise (lack of lubrication, spalling, and so forth), mechanical contact with the roll by other objects, electromagnetic interference (EMI) and radio frequency interference (RFI) from nearby broadcasting facilities and from other sources. This practice should not be used if background noise cannot be eliminated or controlled. 5.7 Other Non-destructive test methods may be used to evaluate the significance of AE indications. Traditional AE has been used to confirm the existence of the AE indication and fine tune the location. Magnetic particle, ultrasonic and radiographic examinations have been used to establish the position, depth and dimensions of the indication. Procedures for using other NDT methods are beyond the scope of this practice. SCOPE 1.1 This practice provides guidelines for acoustic emission (AE) examinations of non-pressure, paper machine rolls. 1.2 This practice utilizes a slow rotation of the roll to produce a full load cycle where load is provided by the weight of the roll suspended from its bearings or other journal support mechanism(s). 1.3 This practice is used for detection of cracks and other discontinuities in rolls that produce frictional acoustic emission during rotation. 1.4 The AE measurements are used to detect or locate emission sources, or both. Other nondestructive test (NDT) methods must be used to evaluate the significance of AE sources. Procedures for other NDT techniques are beyond the scope of this practice. See Note 1. Note 1: Traditional AE examination, magnetic particle examination, shear wave ultrasonic examination, and radiography are commonly used to establish the exact position and dimensions of flaws that produce AE. 1.5 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. 1.6 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. Specific precautionary statements are given in Section 8. 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.
ASTM E2907/E2907M-13(2019) is classified under the following ICS (International Classification for Standards) categories: 17.140.20 - Noise emitted by machines and equipment; 85.100 - Equipment for the paper industry. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM E2907/E2907M-13(2019) has the following relationships with other standards: It is inter standard links to ASTM E2907/E2907M-13, ASTM E1316-24, ASTM E1316-19b, ASTM E1316-19, ASTM E1316-18, ASTM E1316-17a, ASTM E1316-17, ASTM E1316-16a, ASTM E1316-16, ASTM E1316-15a, ASTM E2374-15, ASTM E1316-15, ASTM E1316-14, ASTM E1316-14e1, ASTM E1316-13d. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM E2907/E2907M-13(2019) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: E2907/E2907M − 13 (Reapproved 2019)
Standard Practice for
Examination of Paper Machine Rolls Using Acoustic
Emission from Crack Face Rubbing
ThisstandardisissuedunderthefixeddesignationE2907/E2907M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This practice provides guidelines for acoustic emission
(AE) examinations of non-pressure, paper machine rolls.
2. Referenced Documents
1.2 This practice utilizes a slow rotation of the roll to
2.1 ASTM Standards:
produce a full load cycle where load is provided by the weight
E543 Specification forAgencies Performing Nondestructive
of the roll suspended from its bearings or other journal support
Testing
mechanism(s).
E650 Guide for Mounting Piezoelectric Acoustic Emission
1.3 This practice is used for detection of cracks and other
Sensors
discontinuitiesinrollsthatproducefrictionalacousticemission
E976 GuideforDeterminingtheReproducibilityofAcoustic
during rotation.
Emission Sensor Response
E1316 Terminology for Nondestructive Examinations
1.4 The AE measurements are used to detect or locate
E2075 Practice for Verifying the Consistency of AE-Sensor
emission sources, or both. Other nondestructive test (NDT)
Response Using an Acrylic Rod
methods must be used to evaluate the significance of AE
E2374 Guide for Acoustic Emission System Performance
sources. Procedures for other NDT techniques are beyond the
Verification
scope of this practice. See Note 1.
E2598 Practice for Acoustic Emission Examination of Cast
NOTE 1—Traditional AE examination, magnetic particle examination,
Iron Yankee and Steam Heated Paper Dryers
shear wave ultrasonic examination, and radiography are commonly used
to establish the exact position and dimensions of flaws that produce AE. 2.2 ASNT Standards:
SNT-TC-1A Recommended Practice for Nondestructive
1.5 The values stated in either SI units or inch-pound units
Testing Personnel Qualification and Certification
are to be regarded separately as standard. The values stated in
ANSI/ASNT CP-189 Standard for Qualification and Certifi-
each system may not be exact equivalents; therefore, each
cation of Nondestructive Testing Personnel
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance 2.3 AIA Document
with the standard. NAS-410 Certification and Qualification of Nondestructive
Testing Personnel
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.1 Definitions—See Terminology E1316 for general termi-
mine the applicability of regulatory limitations prior to use.
nology applicable to this practice.
Specific precautionary statements are given in Section 8.
3.2 Definitions of Terms Specific to This Standard:
1.7 This international standard was developed in accor-
3.2.1 crack face rubbing—physical displacement of existing
dance with internationally recognized principles on standard-
crack surfaces as load is changed.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- Standards volume information, refer to the standard’s Document Summary page on
structive Testing and is the direct responsibility of Subcommittee E07.04 on the ASTM website.
Acoustic Emission Method. AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
Current edition approved May 1, 2019. Published June 2019. Originally 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
approved in 2013. Last previous edition approved in 2013 as E2907/E2907M – 13. Available fromAerospace IndustriesAssociation ofAmerica, Inc. (AIA), 1000
DOI: 10.1520/E2907_E2907M-13R19. WilsonBlvd.,Suite1700,Arlington,VA22209-3928,http://www.aia-aerospace.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2907/E2907M − 13 (2019)
3.2.2 crack face rubbing emission—acoustic emission pro- 5.4 Traditional AE examination, whereby the roll is sub-
duced by (frictional mechanisms) within existing cracks that jected to load greater than service load to detect crack
are subjected to a change in load.
extension, risks damage to the roll and is best employed as a
follow-up NDT examination.
3.2.3 crack-face-rubbing emission—is one form of tribo-
acoustic emission.
5.5 Manual rotation through a full revolution subjects ex-
3.2.4 tribo-acoustic emission—stress waves produced by isting cracks to tensile and compressive forces which can open
rubbing of surfaces. and close existing cracks, and cause friction at the crack
surfaces.
4. Summary of Practice
5.6 Excess background noise (overhead cranes, nearby
4.1 The type of paper machine roll that has been most
maintenance activities) may distort AE data or render it
commonly examined using this technique is known as a “felt”
useless.Usersmustbeawareofthefollowingcommonsources
roll.
of background noise: bearing noise (lack of lubrication,
spalling, and so forth), mechanical contact with the roll by
4.2 The felt must be removed or loosened such that a felt
other objects, electromagnetic interference (EMI) and radio
roll can be rotated without causing background noise. Electro-
frequency interference (RFI) from nearby broadcasting facili-
magnetically“jogging”therollmaybeapossibility,depending
ties and from other sources. This practice should not be used if
on the availability of electricity in the mill.
background noise cannot be eliminated or controlled.
4.3 The roll is slowly rotated through 360 degrees, then
rotated back to the original 0 degrees orientation. (Test time is 5.7 Other Non-destructive test methods may be used to
approximately 60 seconds.)
evaluate the significance ofAE indications. TraditionalAE has
been used to confirm the existence of the AE indication and
4.4 This examination procedure describes a technique
fine tune the location. Magnetic particle, ultrasonic and radio-
whereby AE is detected from the rubbing of existing crack
graphic examinations have been used to establish the position,
surfaces. Excessive loading to induce crack propagation is not
depth and dimensions of the indication. Procedures for using
required.
other NDT methods are beyond the scope of this practice.
4.5 The AE sensors are mounted on each end of the roll
(bearing journal or shell, or both).
6. Basis of Application
4.6 Sensors are connected to an acoustic emission signal
6.1 The following items are subject to contractual agree-
processor. The signal processor uses single channel data for
ment between the parties using or referencing this practice.
zone location and measured times of arrival to determine linear
location of emissions sources.
6.2 Personnel Qualification—If specified in the contractual
agreement, personnel performing examinations to this standard
4.7 If measured emission exceeds a prescribed level (that is,
shall be qualified in accordance with a nationally or interna-
specificareasproduceenoughAEactivity),thensuchlocations
tionally recognized NDT personnel qualification practice or
are considered NDT indications and should receive secondary
standardsuchasANSI/ASNT-CP-189,SNT-TC-1A,NAS-410,
NDT examination to determine the severity of the indication.
or a similar document and certified by the employer or
4.8 Secondary examination confirms presence of flaws and
certifying agency, as applicable. The practice or standard used
measures flaw dimensions.
and its applicable revision shall be identified in the contractual
agreement between the using parties.
4.9 If one dimension of the flaw aspect ratio exceeds a
prescribed limit (that is, a conservative limit that is based on
6.3 Qualification of Nondestructive Agencies—If specified
construction material, wall thickness, fatigue crack growth
in the contractual agreement, NDT agencies shall be qualified
estimates, and fracture critical flaw depth calculations), then
and evaluated as described in Specification E543. The appli-
the roll must be removed from service.
cable edition of Specification E543 shall be specified in the
contractual agreement.
5. Significance and Use
6.4 Extent of Examination—The extent of examination in-
5.1 Paper machine rolls can range in size from 2.4 to9m[8
cludes the entire roll unless otherwise specified.
to30ft]long,withashellthicknessoffrom12.5to75mm[0.5
to 3 in.,] and 300 to 1200 mm [12 to 48 in.] diameter.
6.5 Reporting Criteria/Acceptance Criteria—Reporting cri-
Depending on purpose, paper machine rolls can weigh as little
teria for the examination results shall be in accordance with
as 60 000 kg [13 000 lb] to as much as 27 500 kg [60 000 lb].
Section 11unlessotherwisespecified.Sinceacceptancecriteria
(for example, reference radiographs) are not specified in this
5.2 If indications are found during this procedure it can be
practice, they shall be specified in the contractual agreement.
repeated, with additional sensors to refine source location
accuracy.
6.6 Reexamination of Repaired/Reworked Items—
5.3 Removal of rolls for traditional NDT examination may Reexamination of repaired/reworked items is not addressed in
this practice and, if required, shall be specified in the contrac-
be impractical and may not be sensitive enough to locate small
defects. tual agreement.
E2907/E2907M − 13 (2019)
7. Apparatus 7.7.1 A video monitor should display processed examina-
tiondatainvariousformats.Displayformatmaybeselectedby
7.1 Essential features of the apparatus required for this
the equipment operator.
practice are provided in Fig. 1. Full specifications are in Annex
7.7.2 A data storage device, such as a hard drive, may be
A1.
used to provide data for replay or for archives.
7.2 Couplant must be used to acoustically connect sensors
7.7.3 Hard copy capability should be available from a
to the (bare metal) vessel surface.Adhesives that have accept-
printer or equivalent device.
able acoustic properties, and adhesives used in combination
with traditional couplants, are acceptable.
8. Safety Precautions
7.3 Sensors may be held in place with magnets, elastic
8.1 If the roll has been allowed to cool to a very low level,
strips, adhesive tape, or other mechanical means.
the operator should be aware of the ductile-brittle transition
7.4 The AE sensors are used to detect frictionally induced
temperature of the roll’s construction material.
stress waves emanating from the crack surface. Sensors must
be held in contact with the roll to ensure adequate acoustic
9. Calibration and Verification
coupling.
9.1 Annual calibration and verification of signal processor
7.5 Apreamplifier may be enclosed in the sensor housing or
(particularly the signal processor time reference), and AE
in a separate enclosure. If a separate preamplifier is used, cable
electronic waveform generator should be performed. Equip-
length,betweensensorandpreamp,mustnotexceed2m[6ft].
ment should be adjusted so that it conforms to the equipment
7.6 Power/signal cable length (that is, cable between pre- manufacturer’s specifications. Instruments used for calibra-
tions must have current accuracy certification that is traceable
amp and signal processor) shall not exceed 150 m [500 ft]. See
A1.5. to the National Institute for Standards and Technology (NIST)
or equivalent.
7.7 Signal processors are computerized instruments with
independent channels that filter, measure, and convert analog 9.2 Routine electronic evaluation of the signal processor
information into digital form for display and permanent stor- should be performed monthly and any time there is concern
age.Asignal processor must have sufficient speed and capacity about signal processor performance. An AE electronic wave-
to independently process data from all sensors simultaneously. form generator should be used in making evaluations. Each
The signal processor should provide capability to filter data
...
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