ASTM E2096-00
(Practice)Standard Practice for In Situ Examination of Ferromagnetic Heat-Exchanger Tubes Using Remote Field Testing
Standard Practice for In Situ Examination of Ferromagnetic Heat-Exchanger Tubes Using Remote Field Testing
SCOPE
1.1 This practice describes procedures to be followed during remote field examination of installed ferromagnetic heat-exchanger tubing for baseline and service-induced discontinuities.
1.2 This practice is intended for use on ferromagnetic tubes with outside diameters from 0.500 to 2.000 in. (12.70 to 50.80 mm), with wall thicknesses in the range from 0.028 to 0.134 in. (0.71 to 3.40 mm).
1.3 This practice does not establish tube acceptance criteria; the tube acceptance criteria must be specified by the using parties.
1.4 The values stated in either inch-pound units or SI 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 nonconformance with the standard.
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 practice to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E 2096 – 00
Standard Practice for
In Situ Examination of Ferromagnetic Heat-Exchanger Tubes
Using Remote Field Testing
This standard is issued under the fixed designation E 2096; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Can CGSB-48.9712-95 Qualification of Nondestructive
Testing Personnel, Natural Resources Canada
1.1 Thispracticedescribesprocedurestobefollowedduring
remote field examination of installed ferromagnetic heat-
3. Terminology
exchanger tubing for baseline and service-induced discontinui-
3.1 General—Definitions of terms used in this practice can
ties.
be found in Terminology E 1316, Section A, “Common NDT
1.2 This practice is intended for use on ferromagnetic tubes
Terms,” and Section C, “Electromagnetic Testing.”
with outside diameters from 0.500 to 2.000 in. (12.70 to 50.80
3.2 Definitions:
mm),withwallthicknessesintherangefrom0.028to0.134in.
3.2.1 detector, n—one or more coils or elements used to
(0.71 to 3.40 mm).
sense or measure magnetic field; also known as a receiver.
1.3 This practice does not establish tube acceptance criteria;
3.2.2 exciter, n—a device that generates a time-varying
the tube acceptance criteria must be specified by the using
electromagnetic field, usually a coil energized with alternating
parties.
current (ac); also known as a transmitter.
1.4 The values stated in either inch-pound units or SI units
3.2.3 nominal tube, n—a tube or tube section meeting the
are to be regarded separately as standard. The values stated in
tubing manufacturer’s specifications, with relevant properties
each system may not be exact equivalents; therefore, each
typical of a tube being examined, used for reference in
system shall be used independently of the other. Combining
interpretation and evaluation.
values from the two systems may result in nonconformance
3.2.4 remote field, n—as applied to nondestructive testing,
with the standard.
the electromagnetic field which has been transmitted through
1.5 This standard does not purport to address all of the
the test object and is observable beyond the direct coupling
safety concerns, if any, associated with its use. It is the
field of the exciter.
responsibility of the user of this practice to establish appro-
3.2.5 remote field testing, n—a nondestructive test method
priate safety and health practices and determine the applica-
that measures changes in the remote field to detect and
bility of regulatory limitations prior to use.
characterize discontinuities.
2. Referenced Documents 3.2.6 using parties, n—the supplier and purchaser.
3.2.6.1 Discussion—The party carrying out the examination
2.1 ASTM Standards:
is referred to as the “supplier,” and the party requesting the
E 543 Practice for Agencies Performing Nondestructive
2 examination is referred to as the “purchaser,” as required in
Testing
Form and Style for ASTM Standards, October 1999. In
E 1316 Terminology for Nondestructive Examinations
common usage outside this practice, these parties are often
2.2 Other Documents:
referred to as the “operator” and “customer,” respectively.
ASNT SNT-TC-1A Recommended Practice for Nonde-
3.3 Definitions of Terms Specific to This Standard:
structive Testing Personnel Qualification and Certifica-
3.3.1 flaw characterization standard, n—a standard used in
tion
additiontotheRFTsystemreferencestandard,withartificialor
service-induced flaws, used for flaw characterization.
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- 3.3.2 nominal point, n—a point on the phase-amplitude
structive Testing and is the direct responsibility of Subcommittee E07.07 on
diagram representing data from nominal tube.
Electromagnetic Methods.
Current edition approved June 10, 2000. Published August 2000.
Annual Book of ASTM Standards, Vol 03.03.
3 4
Available from American Society for Nondestructive Testing, 1711 Arlingate Available from CGSB Sales Centre; Place du Portage, Phase 3, 6B1; 11 Laurier
Plaza, P.O. Box 28518, Columbus, OH 43228-0518. Street, Hull QC, Canada K1A 1G6.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 2096
3.3.3 phase-amplitude diagram, n—a two-dimensional rep- 3.3.8 zero point, n—apointonthephase-amplitudediagram
resentation of detector output voltage, with angle representing representing zero detector output voltage.
phase with respect to a reference signal, and radius represent-
3.3.8.1 Discussion—Data on the phase-amplitude diagram
ing amplitude (Fig. 1a and 1b). are plotted with respect to the zero point. The zero point is
3.3.3.1 Discussion—In this practice, care has been taken to separate from the nominal point unless the detector is config-
ured for zero output in nominal tube. The angle of a flaw
use the term “phase angle” (and “phase”) to refer to an angular
equivalent of time displacement, as defined in Terminology indication is measured about the nominal point.
E 1316. When an angle is not necessarily representative of 3.4 Acronyms:
time, the general term “angle of an indication on the phase-
3.4.1 RFT, n—remote field testing
amplitude diagram” is used.
3.3.4 RFT system, n—the electronic instrumentation, 4. Summary of Practice
probes, and all associated components and cables required for
4.1 The RFT data is collected by passing a probe through
performing RFT.
each tube. The electromagnetic field transmitted from the
3.3.5 RFT system reference standard, n—a reference stan-
exciter to the detector is affected by discontinuities; by the
dard with specified artificial flaws, used to set up and standard-
dimensions and electromagnetic properties of the tube; and by
ize a remote field system and to indicate flaw detection
objects in and around the tube that are ferromagnetic or
sensitivity.
conductive.SystemsensitivityisverifiedusingtheRFTsystem
3.3.6 sample rate—the rate at which data is digitized for
reference standard. System sensitivity and settings are checked
display and recording, in data points per second.
and recorded prior to and at regular intervals during the
3.3.7 strip chart, n—a diagram that plots coordinates ex- examination. Data and system settings are recorded in a
tracted from points on a phase-amplitude diagram versus time manner that allows archiving and later recall of all data and
or axial position (Fig. 1c). system settings for each tube. Interpretation and evaluation are
FIG. 1 A and B: Typical Phase-Amplitude Diagrams Used in RFT; C: Generic Strip Chart With Flaw
E 2096
carried out using one or more flaw characterization standards. transmission path can create a perturbation; thus RFT has
The supplier generates a final report detailing the results of the approximately equal sensitivity to flaws on the inner and outer
examination. walls of the tube.
5.3 Probe Configuration—The detector is typically placed
5. Significance and Use
two to three tube diameters from the exciter, in a location
where the remote field dominates the direct-coupling field.
5.1 The purpose of RFT is to evaluate the condition of the
Other probe configurations or designs may be used to optimize
tubing. The evaluation results may be used to assess the
flaw detection, as described in 9.3.
likelihood of tube failure during service, a task which is not
5.4 Comparison with Conventional Eddy-Current Testing—
covered by this practice.
Conventionaleddy-currenttestcoilsaretypicallyconfiguredto
5.2 Principle of Probe Operation—In a basic RFT probe,
sense the field from the tube wall in the immediate vicinity of
theelectromagneticfieldemittedbyanexcitertravelsoutwards
the emitting element, whereas RFT probes are typically de-
through the tube wall, axially along the outside of tube, and
signed to detect changes in the remote field.
back through the tube wall to a detector (Fig. 2a).
5.2.1 Flaw indications are created when (1) in thin-walled
6. Basis of Application
areas, the field arrives at the detector with less attenuation and
less time delay, (2) discontinuities interrupt the lines of
6.1 Personnel Qualification:
magnetic flux, which are aligned mainly axially, or (3) discon-
6.1.1 Personnel performing examinations to this practice
tinuities interrupt the eddy currents, which flow mainly cir-
shall be qualified as specified in the contractual agreement.
cumferentially. A discontinuity at any point on the through-
6.1.2 Recommendations for qualification as an RFT system
operator (Level I) are as follows:
6.1.2.1 Forty hours of RFT (Level I) classroom training.
6.1.2.2 Written and practical examinations similar to those
described by ASNT SNT-TC-1A or Can CGSB 48.9712-95.
Schmidt, T. R., “The Remote Field Eddy Current Inspection Technique,”
Materials Evaluation, Vol. 42, No. 2, Feb. 1984, pp. 225-230.
NOTE 1—Arrows indicate flow of electromagnetic energy from exciter to detector. Energy flow is perpendicular to lines of magnetic flux.
FIG. 2 RFT Probes
E 2096
6.1.2.3 Two hundred and fifty hours of field experience 7.1.11 Complementary methods or techniques (including
under the supervision of a qualified RFT Level II, 50 % of possible tube removal) that may be used to obtain additional
which should involve RFT instrumentation setup and opera- information.
tion.
7.1.12 Acceptance criteria to be used in evaluating flaw
6.1.3 Recommendations for qualification as an RFT data
indications.
analyst (Level II) are as follows:
7.1.13 Disposition of examination records and reference
6.1.3.1 Forty hours of RFT (Level II) classroom training.
standards.
6.1.3.2 Written and practical examinations similar to those
7.1.14 Format and outline contents of the examination
described by ASNT SNT-TC-1A or Can CGSB 48.9712-95.
report.
6.1.3.3 Fifteen hundred hours of field experience under the
supervision of a qualified RFT Level II or higher, 25 % of
8. Interferences
which should involve RFT data analysis.
8.1 This section describes items and conditions which may
NOTE 1—At the time of approval of this practice, no nationally or
compromise RFT.
internationally recognized guideline for personnel qualification in RFT
8.2 Material Properties:
was available.
8.2.1 Variations in the material properties of ferromagnetic
NOTE 2—Eddy-current training provides some useful background to
tubes are a potential source of inaccuracy. Impurities, segrega-
RFT training. Previous Level II eddy-current certification may count
tion, manufacturing process, grain size, stress history, present
towards 50 % of training and experience hours for RFT Level I, provided
that the remaining experience hours are entirely involved in RFT stress patterns, temperature history, present temperature, mag-
instrumentation setup and operation.
netic history, and other factors will affect the electromagnetic
response measured during RFT. The conductivity and perme-
6.2 Qualification of Nondestructive Testing Agencies—If
ability of tubes with the same grade of material are often
specified in the contractual agreement, NDT agencies shall be
measurably different. It is common to find that some of the
qualified and evaluated as described in Practice E 543, with
tubes to be examined are newer tubes with different material
reference to sections on electromagnetic testing. The appli-
properties.
cable edition of Practice E 543 shall be specified in the
8.2.2 Permeability variations may occur at locations where
contractual agreement.
there was uneven temperature or stress during tube manufac-
ture, near welds, at bends, where there were uneven heat
7. Job Scope and Requirements
transfer conditions during service, at areas where there is cold
7.1 Thefollowingitemsmayrequireagreementbetweenthe
working (such as that created by an integral finning process),
using parties and should be specified in the purchase document
and in other locations. Indications from permeability variations
or elsewhere:
may be mistaken for, or obscure flaw indications. Effects may
7.1.1 Location and type of tubed component to be exam-
be less severe in tubes that were stress-relieved during manu-
ined, design specifications, degradation history, previous non-
facture.
destructive examination results, maintenance history, process
8.2.3 Residual stress, with accompanying permeability
conditions, and specific types of flaws that are required to be
variations, may be present when discontinuities are machined
detected, if known.
intoareferencestandard,orduringtheintegralfinningprocess.
7.1.2 The maximum window of opportunity for work.
8.2.4 The RFT is affected by residual magnetism in the
(Detection of small flaws may require a slower probe pull
tubing, including residual magnetism created during a previous
speed, which will affect productivity.)
examination using another magnetic method. Tubes with sig-
7.1.3 Size, material grade and type, and configuration of
nificant residual magnetism should be demagnetized prior to
tubes to be examined.
RFT.
7.1.4 A tube numbering or identification system.
8.3 Ferromagnetic and Conductive Objects:
7.1.5 Extent of examination, for example: complete or
8.3.1 Objects near the tube that are ferromagnetic or con-
partial coverage, which tubes and to what length, whether
ductive may reduce the sensitivity and accuracy of flaw
straight sections only, and the minimum radius of bends that
characterization in their immediate vicinity. Such objects may
can be examined.
in some cases be mistaken for flaws. Knowledge of the
7.1.6 Means of access to tubes, and areas where access may
mechanical layout of the component to be examined is recom-
be restricted.
mended. Examples of ferromagnetic or conductive objects
7.1.7 Type of RFT instrument and probe; and description of
include: tube support plates, baffle plates, end plates, tube
reference standards used, including such details as dimensions
sheets, anti-vibration bars, neighboring tubes, impingement
and material.
plates, loose parts, and attachments clamped or welded to a
7.1.8 Required operator qualifications and certification.
tube.
7.1.9 Required tube cleanliness.
7.1.10 Environmental conditions, equipment, and prepara-
NOTE 4—Interference from ferromagnetic or conductive objects can be
tions that are the responsibility of the purchaser; common
of practical use when RFT is used to confirm the position of an object
installed on a tube or to detect where objects have become detached and
sources of noise that may interfere with the examination.
have fallen against a tube.
NOTE 3—Nearby welding activities may be a major source of interfer-
ence. 8.3.2 Neighbori
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