ASTM E2928/E2928M-13
(Practice)Standard Practice for Examination of Drillstring Threads Using the Alternating Current Field Measurement Technique
Standard Practice for Examination of Drillstring Threads Using the Alternating Current Field Measurement Technique
SIGNIFICANCE AND USE
5.1 The purpose of the alternating current field measurement method is to evaluate threads for surface breaking discontinuities such as fatigue cracks running along the thread root. The examination results may then be used to determine the fate of the tool. This may involve re-examination by an alternative technique, immediate scrapping of the tool, or reworking to remove discontinuities (beyond the scope of this practice). This practice is not intended for the examination of threads for non-surface breaking discontinuities.
SCOPE
1.1 This practice describes procedures to be followed during alternating current field measurement examination of drillstring threads on tubulars used for oil and gas exploration and production for detection and, if required, sizing of service-induced surface breaking discontinuities transverse to the pipe.
1.2 This practice is intended for use on threads in any metallic material.
1.3 This practice does not establish acceptance criteria. Typical industry practice is to reject these connections on detection of a confirmed crack.
1.4 While the alternating current field measurement technique is capable of detecting discontinuities in these connections, supplemental surface NDT methods such as magnetic particle testing for ferrous metals and penetrant testing for non-ferrous metals may detect more discontinuities.
1.5 Units—The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system might 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.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E2928/E2928M − 13
Standard Practice for
Examination of Drillstring Threads Using the Alternating
Current Field Measurement Technique
ThisstandardisissuedunderthefixeddesignationE2928/E2928M;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 E1316 Terminology for Nondestructive Examinations
E2216 Guide for Evaluating Disposal Options for Concrete
1.1 Thispracticedescribesprocedurestobefollowedduring
from Nuclear Facility Decommissioning
alternating current field measurement examination of drill-
string threads on tubulars used for oil and gas exploration and 2.2 ASNT Standards
production for detection and, if required, sizing of service- SNT-TC-1A Personnel Qualification and Certification in
induced surface breaking discontinuities transverse to the pipe. Nondestructive Testing
ANSI/ASNT-CP-189 Standard for Qualification and Certifi-
1.2 This practice is intended for use on threads in any
cation of Nondestructive Testing Personnel
metallic material.
1.3 This practice does not establish acceptance criteria.
3. Terminology
Typical industry practice is to reject these connections on
3.1 For definitions of terms relating to this practice refer to
detection of a confirmed crack.
Terminology E1316, Section A, Common NDT terms, and
1.4 While the alternating current field measurement tech-
Section C, Electromagnetic testing. The following definitions
nique is capable of detecting discontinuities in these
are specific to the alternating current field measurement tech-
connections, supplemental surface NDT methods such as
nique:
magnetic particle testing for ferrous metals and penetrant
3.2 Definitions:
testing for non-ferrous metals may detect more discontinuities.
3.2.1 detector—one or more coils or elements used to sense
1.5 Units—The values stated in either inch-pound units or
or measure a magnetic field; also known as a receiver.
SI units are to be regarded separately as standard. The values
3.2.2 exciter—a device that generates a time varying elec-
statedineachsystemmightnotbeexactequivalents;therefore,
tromagnetic field, usually a coil energized with alternating
each system shall be used independently of the other. Combin-
current (AC); also known as a transmitter.
ingvaluesfromthetwosystemsmayresultinnonconformance
with the standard. 3.2.3 uniform field—as applied to nondestructive testing
with magnetic fields, the area of uniform magnetic field over
1.6 This standard does not purport to address all of the
the surface of the material under examination produced by a
safety concerns, if any, associated with its use. It is the
parallel induced alternating current, which has been passed
responsibility of the user of this standard to establish appro-
through the testpiece and is observable beyond the direct
priate safety and health practices and determine the applica-
coupling of the exciting coil.
bility of regulatory limitations prior to use.
3.3 Definitions of Terms Specific to This Standard:
2. Referenced Documents
3.3.1 alternating current field measurement system—the
2.1 ASTM Standards: electronic instrumentation, software, probes, and all associated
E543 Specification forAgencies Performing Nondestructive
componentsandcablesrequiredforperforminganexamination
Testing using the alternating current field measurement technique.
3.3.2 box—the female thread in a drillstring connection.
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
3.3.3 Bx—the x component of the magnetic field, parallel to
structive Testing and is the direct responsibility of Subcommittee E07.07 on
the thread root, the magnitude of which is proportional to the
Electromagnetic Method.
current density set up by the electric field.
Current edition approved June 1, 2013. Published June 2013. DOI: 10.1520/
E2928_E2928M–13.
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
Standards volume information, refer to the standard’s Document Summary page on AvailablefromAmericanSocietyforNondestructiveTesting(ASNT),P.O.Box
the ASTM website. 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http://www.asnt.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2928/E2928M − 13
3.3.4 Bz—the z component of the magnetic field normal to
the examined pipe surface, the magnitude of which is propor-
tional to the lateral deflection of the induced currents in the
plane of that surface.
3.3.5 configuration data—standardization data and instru-
mentation settings for a particular probe stored in a computer
file.
3.3.6 data sample rate—the rate at which data is digitized
for display and recording, in data points per second.
3.3.7 longitudinal—following from the above definition, a
longitudinal discontinuity is parallel to the pipe axis and
therefore perpendicular to the scan direction.
3.3.8 operational standardization block—a reference stan-
dard with specified artificial notches, used to confirm the
operation of the system.
3.3.9 pin—the male thread in a drillstring connection.
3.3.10 satellite signals—Bx and Bz signals observed when
the probe passes a discontinuity in an adjacent thread root.
FIG. 1 Example Bx and Bz Traces as a Probe Passes Over a
3.3.11 surface plot—for use with array probes. This type of
Crack (The orientation of the traces may differ depending upon
plot has one component of the magnetic field plotted over an
the instrumentation.)
area, typically as a color contour plot or 3-D wire frame plot.
3.3.12 time base plots—these plot the relationship between
system software. Discontinuities essentially perpendicular to
Bx or Bz values with time.
the thread may be detected (in ferritic metals only) by the flux
3.3.13 transverse—as is normal in drilling, the terms trans-
leakage effect.
verse and longitudinal are defined in reference to the pipe axis.
4.2 Configuration data is loaded at the start of the exami-
Therefore, a transverse discontinuity is parallel to the thread
nation. System sensitivity and operation is verified using an
andhencetothescandirection.Thisisdifferenttothesituation
operation standardization block. System operation is checked
for weld inspection, covered in Guide E2216.
and recorded prior to and at regular intervals during the
3.3.14 X-Y Plot—an X-Y graph with two orthogonal com-
examination. This can be accomplished using discontinuity-
ponents of magnetic field plotted against each other.
sizing tables in the system software. Data is recorded in a
manner that allows archiving and subsequent recall for each
NOTE 1—Different equipment manufacturers may use slightly different
thread. Evaluation of examination results may be conducted at
terminology. Reference should be made to the equipment manufacturer’s
documentation for clarification.
the time of examination or at a later date. The examiner
generates an examination report detailing complete results of
4. Summary of Practices
the examination.
4.1 In a basic alternating current field measurement system,
5. Significance and Use
a small probe is moved around the thread root. The probe
5.1 The purpose of the alternating current field measure-
contains an exciter coil, which induces anAC magnetic field in
ment method is to evaluate threads for surface breaking
the material surface aligned to the direction of the thread root.
discontinuities such as fatigue cracks running along the thread
This, in turn, causes alternating current to flow across the
root. The examination results may then be used to determine
threads. The depth of penetration of this current varies with
the fate of the tool. This may involve re-examination by an
material type and frequency but is typically 0.004 in. [0.1 mm]
alternative technique, immediate scrapping of the tool, or
deepinmagneticmaterialsand0.08to0.3in.[2to7mm]deep
reworking to remove discontinuities (beyond the scope of this
in non-ferrous materials. Any surface breaking discontinuities
practice). This practice is not intended for the examination of
within a short distance of either side of the scan line at this
threads for non-surface breaking discontinuities.
location will interrupt or disturb the flow of the alternating
current. Measurement of the absolute quantities of the two
6. Basis of Application
major components of the surface magnetic fields (Bx and Bz)
determines the severity of the disturbance (see Fig. 1) and thus 6.1 Personnel Qualification—if specified in the contractual
the severity of the discontinuity. Discontinuity sizes, such as agreement, personnel performing examinations to this practice
crack length and depth, can be estimated from the values of shall be qualified in accordance with a nationally or interna-
these quantities or the physical locations of key points, or both, tionally recognized NDT personnel qualification practice or
selected from the Bx and Bz traces along with the standardiza- standard such as ANSI/ASNT-CP-189 or SNT-TC-1A or a
tion data and instrument settings from each individual probe. similar document and certified by the employer or certifying
This discontinuity sizing can be performed automatically using agent, as applicable. The practice or standard used and its
E2928/E2928M − 13
applicable revision shall be identified in the contractual agree- amplitude two or more threads away along the pipe axis then
ment between the using parties the indication is likely due to the permeability changes in the
component.
6.2 Qualification of Nondestructive Evaluation Agencies—if
specified in the contractual agreement, NDT agencies shall be 8.3 Magnetic State:
qualified and evaluated as described in Specification E543, 8.3.1 Demagnetization—It must be ensured that the surface
withreferencetosectionsonelectromagneticexamination.The being examined is in a low magnetization state, or that any
applicable edition of Specification E543 shall be specified in magnetization is uniform over the surface. Therefore the
the contractual agreement. procedure followed with any previous magnetic technique
deployed must include demagnetization of the surface, or
7. Job Scope and Requirements
ensuring that connections are magnetically saturated. This is
because areas of remnant magnetization, particularly where the
7.1 The following items may require agreement by the
examining party and their client and should be specified in the leg of a magnetic particle examination yoke was sited, can
produce loops in the X-Y plot, which may sometimes be
purchase document or elsewhere:
7.1.1 Location and type of threaded component to be confused with a discontinuity indication.
examined, design specifications, degradation history, previous
8.4 Thread Geometry:
nondestructive examination results, maintenance history, pro-
8.4.1 When a probe scans away from the shoulder of a pin
cess conditions, and specific types of discontinuities that are
connection, the Bx indication value will decrease with little
required to be detected, if known.
change in the Bz value. In the representative plot of Fig. 2, this
7.1.2 The maximum recommended probe scan speed is to
appears as a drop in the X-Yplot. The Bx indication value will
be stated by the manufacturer. However, detection of smaller
also decrease as a probe approaches the open end of a thread
discontinuities requires a slower probe scan speed or cleaning
(pin or box).
of surface, or both.
8.5 Crack Geometry Effects:
7.1.3 Size, material grade and type, and configuration of
8.5.1 Sincetheeffectofadiscontinuityonthesignalscanbe
threads to be examined.
detected some distance away, “satellite” signals are observed
7.1.4 A thread numbering or identification system.
as the probe passes one thread (or two threads) away from a
7.1.5 Extent of examination, for example: complete or
sufficiently-large discontinuity. The satellite signals will be
partial coverage, which threads and to what extent.
smaller than the main discontinuity signal, and symmetrically
7.1.6 Type of alternating current field measurement instru-
spaced one thread revolution either side. Care should be taken
ment and probe; and description of operations standardization
not to classify these signals as additional discontinuities.
block used, including such details as dimensions and material.
8.5.2 Alarge discontinuity may jump across a thread crown
7.1.7 Required thread cleanliness.
fromoneroottotheneighboringone.Thiscausesasuddenrise
7.1.8 Environmental conditions, equipment and prepara-
tions that are the responsibility of the client; common sources
ofnoise that may interferewiththeexamination,suchasmotor
drive for rotary table.
7.1.9 Complementary methods or techniques may be used
to obtain additional information.
7.1.10 Acceptance criteria to be used in evaluating discon-
tinuities.
7.1.11 Disposition of examination records and reference
standards.
7.1.12 Format and outline contents of the examination
report.
8. Interferences
8.1 This section describes items and conditions, which may
compromise the alternating current field measurement tech-
nique.
8.2 Material Properties:
8.2.1 Although there are unlikely to be permeability differ-
ences in a ferromagnetic material between different parts of a
thread, if a probe is scanned across a permeability change such
as an area of residual magnetism, this may produce indications
which could be similar to those from a discontinuity. Differ-
entiation between a discontinuity signal and a permeability
change signal can be achieved by comparing scans from
FIG. 2 Example X-Y Plot Produced by Plotting the Bx (vertical)
neighboring threads. The signal from a discontinuity will die
and Bz (horizontal) Together (The orientation of the plot may dif-
away quickly. If there is no significant change in indication fer depending upon the instrumentation.)
E2928/E2928M − 13
in Bx signal where the discontinuity leaves the root, and a display, data analysis and data storage. The software provides
sudden decrease in Bx signal at the same place in the algorithms for sizing the discontinuities (see Section 14). The
neighboring thread where the discontinuity enters the root. software runs on the PC and, on start up, all communications
8.5.3 Line Contact—when contacts occur across a disconti- between the PC and the instrument are automatically checked.
nuity then minor loops occur within the main X-Y plot loop When the software starts up, it automatically sets up the
produced by the discontinuity. This can be
...
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