ASTM E215-22

Standard Practice for Standardizing Equipment and Electromagnetic Examination of Seamless Aluminum-Alloy Tube

SIGNIFICANCE AND USE
4.1 The examination is performed by passing the tube lengthwise through or near an eddy current sensor energized with alternating current of one or more frequencies. The electrical impedance of the eddy current sensor is modified by the proximity of the tube. The extent of this modification is determined by the distance between the eddy current sensor and the tube, the dimensions, and electrical conductivity of the tube. The presence of metallurgical or mechanical discontinuities in the tube will alter the apparent impedance of the eddy current sensor. During passage of the tube, the changes in eddy current sensor characteristics caused by localized differences in the tube produce electrical signals which are amplified and modified to actuate either an audio or visual signaling device or a mechanical marker to indicate the position of discontinuities in the tube length. Signals can be produced by discontinuities located either on the external or internal surface of the tube or by discontinuities totally contained within the tube wall.  
4.2 The depth of penetration of eddy currents in the tube wall is influenced by the conductivity (alloy) of the material being examined and the excitation frequency employed. As defined by the standard depth of penetration equation, the eddy current penetration depth is inversely related to conductivity and excitation frequency (Note 2). Beyond one standard depth of penetration (SDP), the capacity to detect discontinuities by eddy currents is reduced. Electromagnetic examination of seamless aluminum alloy tube is most effective when the wall thickness does not exceed the SDP or in heavier tube walls when discontinuities of interest are within one SDP. The limit for detecting metallurgical or mechanical discontinuities by way of conventional eddy current sensors is generally accepted to be approximately three times the SDP point and is referred to as the effective depth of penetration (EDP).
Note 2: The standard depth of penetratio...
SCOPE
1.1 This practice2 is for standardizing eddy current equipment employed in the examination of seamless aluminum-alloy tube. Artificial discontinuities consisting of flat-bottomed or through holes, or both, are employed as the means of standardizing the eddy current system. General requirements for eddy current examination procedures are included.  
1.2 Procedures for fabrication of reference standards are given in X1.1 and X2.1.  
1.3 This practice is intended for the examination of tubular products having nominal diameters up to 4 in. (101.6 mm) and wall thicknesses up to the standard depth of penetration (SDP) of eddy currents for the particular alloy (conductivity) being examined and the examination frequency being used.  
Note 1: This practice may also be used for larger diameters or heavier walls up to the effective depth of penetration (EDP) of eddy currents as long as adequate resolution is obtained and as specified by the using party or parties.  
1.4 This practice does not establish acceptance criteria. They must be established by the using party or parties.  
1.5 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered 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-May-2022
• ICS: 77.040.20 - Non-destructive testing of metals
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.07 - Electromagnetic Method

Relations

• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-19b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2019
• Refers: ASTM E1316-19 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Mar-2019
• Refers: ASTM E1316-18 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jan-2018
• Refers: ASTM E1316-17a - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2017
• Refers: ASTM E1316-17 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2017
• Refers: ASTM E1316-16a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Aug-2016
• Refers: ASTM E1316-16 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2016
• Refers: ASTM E1316-15a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2015
• Refers: ASTM E1316-15 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2015
• Refers: ASTM E1316-14e1 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-14 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-13d - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2013
• Refers: ASTM E1316-13c - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2013
• Refers: ASTM E1316-13b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2013

Overview

ASTM E215-22: Standard Practice for Standardizing Equipment and Electromagnetic Examination of Seamless Aluminum-Alloy Tube is an international standard developed by ASTM for nondestructive testing (NDT) of aluminum-alloy tubes. This standard specifies procedures for standardizing eddy current equipment and provides guidance for the electromagnetic examination of seamless aluminum-alloy tubes. The primary aim is to detect metallurgical or mechanical discontinuities within tube walls using eddy current techniques, improving quality assurance within manufacturing and fabrication environments.

Key Topics

• Eddy Current Examination: Tubes are examined by passing them lengthwise through or near eddy current sensors energized with alternating current. The presence of discontinuities-whether surface or subsurface-causes measurable changes in sensor impedance, which can then trigger audio, visual, or mechanical signals.

• Penetration Depth: The capacity to detect flaws is influenced by tube alloy conductivity and excitation frequency. The wall thickness that can be effectively examined depends on the standard depth of penetration (SDP), which is inversely related to both conductivity and frequency.

• Standardization Procedures: The document specifies the use of artificial discontinuities, such as flat-bottomed or through holes, to standardize and calibrate the eddy current system. Reference standard fabrication processes are provided to ensure reliable test results.

• Reference Standards: Primary and secondary reference standards must match the alloy, temper, outside diameter, and wall thickness of the tubes under test, ensuring that devices are calibrated to realistic operational conditions.

• Examination Conditions: The standard addresses proper settings for frequency, speed, phase, filtering, sensitivity, and alarm threshold, all of which are vital for optimizing flaw detection and minimizing false positives.

• Operational Considerations: The standard requires frequent verification-at least every four hours during continuous testing-of instrument performance, with re-standardization prompted by equipment malfunctions.

Applications

• Quality Control: Utilized in manufacturing centers and quality assurance laboratories to ensure the integrity of seamless aluminum-alloy tubes used in critical applications, such as aerospace, automotive, and industrial piping.

• Detection of Defects: Effective at identifying flaws such as cracks, voids, or other types of discontinuities that may impair performance or safety.

• Production Efficiency: Enables quick, non-destructive assessment of tubular products up to 4 inches in nominal diameter, or larger as long as specifications for effective penetration are satisfied.

• Employment in Different Stages: The standard can be applied post-drawing, post-annealing, or even prior to final heat treatment, providing flexibility in integration with various stages of tube production and finishing.

• Customization: Can be adapted to meet specific customer requirements, especially relating to acceptable defect thresholds, frequency selections, and resolution needs.

Related Standards

• ASTM E543: Specification for Agencies Performing Nondestructive Testing.
• ASTM E1316: Terminology for Nondestructive Examinations.
• ISO 9712: Non-Destructive Testing-Qualification and Certification of NDT Personnel.
• SNT-TC-1A: Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing.
• ANSI/ASNT-CP-189: ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel.
• Fed. Std. No. 245D: Tolerance for Aluminum Alloy and Magnesium Alloy Wrought Products.
• NAS-410: NAS Certification and Qualification of Nondestructive Personnel.

ASTM E215-22 is essential for organizations employing nondestructive testing of seamless aluminum-alloy tubes, providing the framework required for reliable flaw detection, enhanced safety, and compliance with international quality standards. By adhering to the standard, manufacturers and inspectors can ensure robust quality control while achieving efficient, repeatable examination results.

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: E215 − 22
Standard Practice for
Standardizing Equipment and Electromagnetic Examination
of Seamless Aluminum-Alloy Tube
This standard is issued under the fixed designation E215; the number immediately following the designation indicates the year 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* ization established in the Decision on Principles for the
2 Development of International Standards, Guides and Recom-
1.1 This practice is for standardizing eddy current equip-
mendations issued by the World Trade Organization Technical
mentemployedintheexaminationofseamlessaluminum-alloy
Barriers to Trade (TBT) Committee.
tube. Artificial discontinuities consisting of flat-bottomed or
throughholes,orboth,areemployedasthemeansofstandard-
2. Referenced Documents
izing the eddy current system. General requirements for eddy
2.1 ASTM Standards:
current examination procedures are included.
E543Specification forAgencies Performing Nondestructive
1.2 Procedures for fabrication of reference standards are
Testing
given in X1.1 and X2.1.
E1316Terminology for Nondestructive Examinations
1.3 This practice is intended for the examination of tubular
2.2 Federal Standard:
products having nominal diameters up to 4 in. (101.6 mm) and
Fed Std. No.245DTolerance for Aluminum Alloy and
wall thicknesses up to the standard depth of penetration (SDP)
Magnesium Alloy Wrought Products
of eddy currents for the particular alloy (conductivity) being
3. Terminology
examined and the examination frequency being used.
3.1 Definitions—For definitions of terms used in this
NOTE1—Thispracticemayalsobeusedforlargerdiametersorheavier
walls up to the effective depth of penetration (EDP) of eddy currents as practice, refer to Terminology E1316.
longasadequateresolutionisobtainedandasspecifiedbytheusingparty
or parties.
4. Significance and Use
1.4 This practice does not establish acceptance criteria.
4.1 The examination is performed by passing the tube
They must be established by the using party or parties.
lengthwise through or near an eddy current sensor energized
with alternating current of one or more frequencies. The
1.5 Units—The values stated in inch-pound units are to be
electrical impedance of the eddy current sensor is modified by
regarded as the standard. The values given in parentheses are
the proximity of the tube. The extent of this modification is
mathematical conversions to SI units that are provided for
determined by the distance between the eddy current sensor
information only and are not considered standard.
and the tube, the dimensions, and electrical conductivity of the
1.6 This standard does not purport to address all of the
tube.The presence of metallurgical or mechanical discontinui-
safety concerns, if any, associated with its use. It is the
ties in the tube will alter the apparent impedance of the eddy
responsibility of the user of this standard to establish appro-
currentsensor.Duringpassageofthetube,thechangesineddy
priate safety, health, and environmental practices and deter-
currentsensorcharacteristicscausedbylocalizeddifferencesin
mine the applicability of regulatory limitations prior to use.
the tube produce electrical signals which are amplified and
1.7 This international standard was developed in accor-
modifiedtoactuateeitheranaudioorvisualsignalingdeviceor
dance with internationally recognized principles on standard-
a mechanical marker to indicate the position of discontinuities
in the tube length. Signals can be produced by discontinuities
This practice is under the jurisdiction of ASTM Committee E07 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.07 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Electromagnetic Method. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved Standards volume information, refer to the standard’s Document Summary page on
in 1963. Last previous edition approved in 2016 as E215–16. DOI: 10.1520/ the ASTM website.
E0215-22. Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
For ASME Boiler and Pressure Vessel Code applications, see related Practice Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
SE-215 in the Code. dodssp.daps.dla.mil.
*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
E215 − 22
located either on the external or internal surface of the tube or 6.2 Eddy Current Sensors—Eddy current sensors shall be
by discontinuities totally contained within the tube wall. capableofinducingcurrentsinthetubeandsensingchangesin
the electrical characteristics of the tube. The eddy current
4.2 The depth of penetration of eddy currents in the tube
sensors may be of the encircling coil (annular) type or surface
wall is influenced by the conductivity (alloy) of the material
probe type.
being examined and the excitation frequency employed. As
definedbythestandarddepthofpenetrationequation,theeddy
7. Standardization of Apparatus
current penetration depth is inversely related to conductivity
7.1 The apparatus shall be adjusted with an appropriate
and excitation frequency (Note 2). Beyond one standard depth
reference standard to ensure that the equipment is operating at
of penetration (SDP), the capacity to detect discontinuities by
the proper level of sensitivity, with the following consider-
eddy currents is reduced. Electromagnetic examination of
ations:
seamless aluminum alloy tube is most effective when the wall
7.1.1 Primary reference standards employed for this pur-
thickness does not exceed the SDP or in heavier tube walls
pose shall be prepared in accordance with the methods de-
when discontinuities of interest are within one SDP. The limit
scribed in X1.1.
for detecting metallurgical or mechanical discontinuities by
7.1.1.1 Other primary standards including notches may be
wayofconventionaleddycurrentsensorsisgenerallyaccepted
used if agreed upon by both purchaser and supplier. Documen-
to be approximately three times the SDP point and is referred
tations showing suitability of alternate standards should be
to as the effective depth of penetration (EDP).
available.
NOTE 2—The standard depth of penetration is defined by the following
7.1.2 Equivalent secondary reference standards, prepared in
equations:
accordance with methods described in X2.1, also may be
employed for standardizing the apparatus.
SDP 5503.3
Œ
7.1.2.1 Othersecondarystandardsincludingnotchesmaybe
fσ
used if agreed upon by both purchaser and supplier. Documen-
where:
tation showing suitability of alternate standards should be
SDP = one standard depth of penetration, m,
available.
f = frequency, Hz (cycles per second), and
7.1.3 Reference standards normally are of the same alloy,
σ = conductivity, Siemens/metre.
temper, and dimensions as the tube to be examined.
7.1.4 Examinationsshallnotbeconductedunlesstheequip-
or:
ment can be set to the levels required by this standardization
procedure.
SDP 526Œ
fσ
7.1.5 For practical applications, reference standards also
may be employed to establish quality control levels.
where:
SDP = one standard depth of penetration, in.,
8. Procedure
f = frequency in Hz (cycles per second), and
8.1 Standardize the examination instrument using the ap-
σ = conductivity,% IACS.
propriate reference standard prior to examination and check at
least every 4 h during continuous operation, or whenever
5. Basis of Application
improper functioning of the examination apparatus is sus-
5.1 If specified in the contractual agreement, personnel
pected. If improper functioning occurs, restandardize the
performing examinations to this practice shall be qualified in
apparatus in accordance with Section 7, and reexamine all
accordance with a nationally recognized NDTpersonnel quali-
tubes examined since the last successful standardization. Time
fication practice or standard and certified by the certifying
between standardization can be increased based upon docu-
agency as applicable. The practice or standard used and its
mented evidence of instrument stability but shall not exceed
applicable revision shall be specified in the contractual agree-
12h.
ment between the using parties.
8.2 Tubes may be examined in the final drawn, annealed, or
5.2 If specified in the contractual agreement, NDT agencies
heat-treated temper, or in the drawn temper prior to the final
shall be qualified and evaluated in accordance with Specifica-
anneal or heat treatment.
tion E543. The applicable edition of Specification E543 shall
8.3 The length of tube over which end effect is significant
be specified in the contractual agreement.
may be determined by placing a series of holes or notches in
special reference tubes and determining the distance from the
6. Apparatus
tubeendatwhichthesignalamplitudefromthediscontinuities
6.1 Electronic Apparatus—Theelectronicapparatusshallbe
begins to decrease.
capable of energizing eddy current sensors with alternating
8.3.1 When standardizing and testing using secondary stan-
currentsofsuitablefrequenciesandshallbecapableofsensing
dard Method B (X2.5.2), if full length testing is required, the
the changes in the electromagnetic characteristics of the eddy
tube must be ordered to be electromagnetic tested in a rough
current sensors. Equipment may include a detector, phase
cut length and have the untested 7 in. (175 mm) removed from
discriminator, filter circuits, gating circuits, and signaling
each end.
devices as required for the particular application. NOTE 3—There is an area near each end which cannot be tested either
E215 − 22
because of an alarm from end effect or because end suppression is used to
height from the appropriate artificial discontinuities to the
eliminate an alarm from end effect. Up to 7 in. (175 mm) on each end is
indication height from non-detrimental discontinuities.
tobeconsidereduntested,regardlessofthestandardused.Customersmust
9.3.4 Filter Setting—The filter setting should be selected
specify if they want these untested areas removed.
commensuratewiththeexaminationspeedtoprovideoptimum
9. Application
filtering of non-detrimental, time-varying discontinuities such
as geometry, pathline variation, high-frequency noise, etc.
9.1 Thisapplicationcoverstheelectromagneticexamination
9.3.5 Sensitivity Setting—The sensitivity setting shall be
of aluminum-alloy seamless tube using primary and secondary
adjusted to provide clearly discernible indications of a conve-
reference standards.
nient height for the appropriate accept holes (A or d ), but it
a
9.2 Primaryandsecondaryreferencestandards,describedin
shall not be high enough to cause off-scale or saturated
X1.1 and X2.1, respectively, when used as acceptance
indications for the appropriate reject holes (2A or d)ofthe
b
standards, will establish probable detection of defects that are
reference standard.
of a severity likely to cause leaks or substantial weakening of
9.3.6 Threshold-Level Setting—The threshold-level setting
the tube.
(rejectlevel)shallbeadjustedtoautomaticallytriggeranaudio
9.3 Using electronic apparatus and eddy current sensors
or visual-signaling device or a mechanical marker when the
described in Section 6, the equipment sensitivity shall be
appropriate artificial discontinuity (or discontinuities) of the
standardized in accordance with Section 7 under the following
acceptance standard passes through or by the eddy current
examination conditions:
sensor.
9.3.1 Frequency—The examination frequency should be in
9.4 Using Reference Standards as Acceptance Standards:
the range from 1 to 125 kHz. Other frequencies or multiple
9.4.1 Method A (X2.1) Reference Standards: When using
frequencies can be used if there is documented evidence of
referencestandardsasacceptancestandards,thethresholdlevel
suitability for the purpose of this examination. The examina-
should be adjusted to accept tubes exhibiting eddy current
tionfrequencyshouldbeadjustedtoprovideoptimumpenetra-
responses smaller than those obtained from the appropriate
tion of the tube wall or to place discontinuities of interest
reject holes (2A or d ) and to reject those with responses
b
within one SDP. Discontinuities located deeper than the SDP
equivalent to or greater than those obtained from the appropri-
point will be detected with less sensitivity. The SDPpoint will
aterejectholes(2Aor d )inthereferencestandard.Experience
b
vary as a function of the tube alloy (conductivity) and
shows that this procedure will aid in the rejection of severe
examination frequency and may be determined by the depth of
defects and, at the same time, minimize erroneous rejection of
penetration equation given in Section 4, Note 2.
tubes that might exhibit noise from non-detrimental disconti-
9.3.2 Speed of Examination—The examination rate, or
nuities.
speed of the tube with respect to the eddy current sensor, may
9.4.2 Method B (X2.2) Reference Standard Selection: Ref-
vary with the application. In encircling coil applications,
erence standards selected for use must be the same alloy,
examinationspeedsof50ft/min(15m/min)to500ft/min(150
temper, diameter, and wall thickness as the material being
m/min) are recommended where possible, but examination
tested.Thereferencestandardselectedforusemustcontainthe
speeds as high as 1000 ft/min (300 m/min) are permissible. In
proper size reject holes and must have been fabricated and
surface probe applications, examination speeds are inherently
identified in accordance with this procedure.
slower due to reduced surface coverage and the necessity to
9.4.2.1 When using reference standards as acceptance
rotate the eddy current sensor or the tube to produce a helical
standards, the threshold level should be adjusted as required in
scan. All instrument adjustments, that is, frequency, phase
X2.5.2.2.Tubesthatdonotexceedthealarmlimitsestablished
setting,filtersetting,sensitivitysetting,threshold-levelsetting,
by the reference standard shall be considered as acceptable
etc., shall be made with the reference standard or acceptance
under this method.
standard or both passing through or by the eddy current sensor
at the same speed at which the examination of tube is to be
10. Keywords
conducted.
9.3.3 Phase Setting—The phase setting should be selected 10.1 aluminum alloy; eddy currents; electromagnetic ex-
to provide the best signal-to-noise ratio for the reference amination; equipment standardization; NDT; nondestructive
standard employed, that is, the maximum ratio of indication testing; tubing
E215 − 22
APPENDIXES
(Nonmandatory Information)
X1. PURPOSE, DESCRIPTION, FABRICATION, AND CHECKING OF PRIMARY REFERENCE STANDARDS
d 5 k D/t 310 (X1.1)
X1.1 Purpose ~ !
X1.1.1 Primary reference standards are used to standardize
where:
examinationequipmentunderoperatingconditionstoestablish
d = drill diameter of A and 2A flat-bottom holes, in. (mm),
acceptable limits of sensitivity, reproducibility, and capability
k = 3.0 in. (76 mm),
for detecting defects of a severity likely to cause leaks or
D = tube outside diameter, in. (mm), and
substantial weakening of the tube.
t = tube wall thickness, in. (mm).
X1.1.2 Thedimensionsoftheappropriateprimaryreference
X1.2.5 In computing the appropriate drill diameters, it is
standardaredeterminedbythesizeofthetubetobeexamined.
recommendedthatthenominaldimensionsfor Dand tlistedin
Aprimary reference standard shall be a tube of the same alloy,
Table X1.1 be used for tubes having heavy or very thin wall
temper, outside diameter, D, and wall thickness, t, as the tube
thicknesses or outside diameter-to-wall thickness ratios that
to be examined. This appendix covers the preparation of
calculate to drill sizes outside the standard drill size range of
primary standards for test of seamless aluminum-alloy tube.
gageNo.1togageNo.80.Thedimensions D, t,and dmustbe
expressed in the same units of measurement, that is, inches or
X1.2 Description
millimetres when calculating the appropriate drill diameters.
X1.2.1 The primary reference standard shall contain six
X1.2.6 A standard drill size (drill gage between No. 1 and
artificial discontinuities in the form of flat-bottomed drilled
No. 80 inclusive) nearest the calculated drill diameter, d, may
holes in a 6ft (180cm) length of tube which is free of
be employed for drilling the hole size required.
significant natural discontinuities. Fig. X1.1 describes the
primary reference standard for aluminum-alloy seamless tube.
X1.3 Identification
X1.2.2 The six flat-bottomed holes shall be of equal
X1.3.1 Each primary reference standard shall be clearly
diameter, d,andshallbelocatedinthemid-portionofthetube.
marked within the first 2 in. (50 mm) from the end of the tube
The distance between adjacent holes is 6 in. (150 mm). The
adjacent to the 2A holes. The standard shall be marked in a
minimum distance between a hole and either end of the tube
manner that provides rapid identification of the manufacturer,
shall be approximately 20 in. (500 mm).
outsidediameter,wallthickness,identifyingnumber,alloy,and
X1.2.3 Three of each of the reference standard holes A and temper. Permanent identification shall be accomplished by a
2Ashallbedrilledconsecutivelytodepthsofonethirdandtwo method not harmful to the tube.
thirds the wall thickness, respectively in radial longitudinal
X1.3.2 As a further means of identification, the primary
planes 120 6 5° apart.
reference standard may be anodized and dyed. This anodizing
X1.2.4 The diameter, d, of the flat-bottomed drill used to and coloring provides positive identification and a wear-
make a primary reference standard hole shall be determined resistant surface and does not affect the eddy current response
mathematically with the following equation: characteristics of the primary reference standard. Caution
NOTE 1—Tolerance: in. 6 0.2 in. (mm 6 5 mm).
NOTE 2—All hole diameters determined by:
-3
d=×10 (tube diameter, t) in.
-3
(d=76.2×10 (tube diameter, D/wall thickness, t) mm)
NOTE 3—A holes and 2A holes are flat-bottomed and are one third the wall thickness deep and two thirds the wall thickness deep, respectively.
NOTE 4—Nominal dimensions for D and t are recommended from Table X1.1 when calculating appropriate drill diameters for tubes having D/t ratios
that result in hole sizes outside the standard drill size range of No. 1 to No. 80.
FIG. X1.1 Primary Reference Standard for Seamless Aluminum-Alloy Tube
E215 − 22
TABLE X1.1 Applicable Primary and Secondary Standard Nominal Dimensions and Drill Sizes for Various Ranges of Tube Sizes
Inch-Pound, in.
Tube Size Nominal Standard Dimensions Drill Size
Wall
Primary Secondary
Dia.,
Outside Diameter Thickness,
D±10%
Dia., d Dia., d Dia., d
a b
t±10%
#0.0625 to 0.125 0.0938 0.015 0.023 0.010 0.015
>0.125 to 0.250 0.1875 0.022 0.026 0.013 0.019
>0.250 to 0.375 0.3125 0.035 0.027 0.014 0.020
>0.375 to 0.500 0.4375 0.049 0.027 0.014 0.020
>0.500 to 0.625 0.5625 0.049 0.034 0.018 0.027
>0.625 to 0.750 0.6875 0.049 0.042 0.021 0.032
>0.750 to 1.000 0.8750 0.049 0.054 0.028 0.042
>1.000 to 1.250 1.125 0.058 0.058 0.030 0.045
>1.250 to 1.500 1.375 0.058 0.071 0.036 0.055
>1.500 to 1.750 1.625 0.067 0.073 0.038 0.057
>1.750 to 2.000 1.875 0.067 0.083 0.043 0.065
>2.000 to 2.500 2.250 0.076 0.089 0.046 0.069
>2.500 to 3.000 2.750 0.083 0.099 0.051 0.077
>3.000 to 3.500 3.250 0.095 0.103 0.053 0.080
>3.500 to 4.000 3.750 0.095 0.118 0.061 0.092
SI Units, mm
Wall Primary Second
Outside Diameter Dia., D
Thickness, t Dia., d Dia., d Dia., d
a b
#1.59 to 3.18 2.38 0.38 0.58 0.25 0.38
>3.18 to 6.35 4.76 0.56 0.66 0.33 0.48
>6.35 to 9.53 7.94 0.89 0.69 0.36 0.51
>9.53 to 12.70 11.11 1.24 0.69 0.36 0.51
>12.70 to 15.88 14.29 1.24 0.86 0.46 0.69
>15.88 to 19.05 17.46 1.24 1.07 0.53 0.81
>19.05 to 25.40 22.23 1.24 1.37 0.71 1.07
>25.40 to 31.75 28.58 1.47 1.47 0.76 1.14
>31.75 to 38.10 34.93 1.47 1.80 0.91 1.40
>38.10 to 44.45 41.28 1.70 1.85 0.97 1.45
>44.45 to 50.80 47.63 1.70 2.11 1.09 1.65
>50.80 to 63.50 57.15 1.93 2.26 1.17 1.75
>63.50 to 76.20 69.85 2.11 2.51 1.30 1.96
>76.20 to 88.90 82.55 2.41 2.62 1.35 2.03
>88.90 to 101.60 95.25 2.41 3.00 1.55 2.34
shouldbeexercisedtomaintainauniformanodiccoatingalong X1.4.4 Tube stock for fabrication of the reference standard
the entire length of the tube because boundaries between shall be free of surface irregularities, bends, and other obvious
anodized and unanodized areas may appear as discontinuities defectsandshallhavenoboworout-of-roundnessinexcessof
during testing. themaximumspecifiedfortube.(SeeFed.Std.No245.)Tubes
shall be free of any eddy current indication greater than 80%
X1.4 Fabricating Procedure
of the A hole indication prior to fabrication of the standard.
X1.4.1 The fabricating procedure includes cutting the tube
X1.5 Checking
to length, locating and drilling the flat-bottomed holes, deburr-
ing and finishing the sawed ends, and identifying the tube as X1.5.1 The finished primary reference standard should be
prescribed by X1.3.The use of a jig with suitable interchange- recheckedbyrecognizedgaugingprocedurestoensurethatthe
able drill bushings is recommended for drilling the flat- outsidediameterwallthickness,maximumbow,andmaximum
bottomed holes. out-of-roundness fall within requirements.
X1.4.2 The original outside and inside surfaces of the tube X1.5.2 Each primary reference standard shall be subjected
shall
...

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: E215 − 16 E215 − 22
Standard Practice for
Standardizing Equipment and Electromagnetic Examination
of Seamless Aluminum-Alloy Tube
This standard is issued under the fixed designation E215; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This practice is for standardizing eddy current equipment employed in the examination of seamless aluminum-alloy tube.
Artificial discontinuities consisting of flat-bottomed or through holes, or both, are employed as the means of standardizing the eddy
current system. General requirements for eddy current examination procedures are included.
1.2 Procedures for fabrication of reference standards are given in Appendixes X1.1 and X2.1.
1.3 This practice is intended for the examination of tubular products having nominal diameters up to 4 in. [101.6 mm](101.6 mm)
and wall thicknesses up to the standard depth of penetration (SDP) of eddy currents for the particular alloy (conductivity) being
examined and the examination frequency being used.
NOTE 1—This practice may also be used for larger diameters or heavier walls up to the effective depth of penetration (EDP) of eddy currents as long as
adequate resolution is obtained and as specified by the using party or parties.
1.4 This practice does not establish acceptance criteria. They must be established by the using party or parties.
1.5 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are
mathematical conversions to SI units that are provided for information only and are not considered standard.
1.6 This standard does not purport to address all of the safety problems,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.
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.
This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.07 on Electromagnetic
Method.
Current edition approved Dec. 1, 2016June 1, 2022. Published January 2017July 2022. Originally approved in 1963. Last previous edition approved in 20112016 as
E215E215 – 16. -11. DOI: 10.1520/E0215-16.10.1520/E0215-22.
For ASME Boiler and Pressure Vessel Code applications, see related Practice SE-215 in the Code.
*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
E215 − 22
2. Referenced Documents
2.1 ASTM Standards:
E543 Specification for Agencies Performing Nondestructive Testing
E1316 Terminology for Nondestructive Examinations
2.2 Federal Standard:
Fed Std. No. 245D Tolerance for Aluminum Alloy and Magnesium Alloy Wrought Products
2.3 Other Documents:
SNT-TC-1A Recommended Practice for Personnel Qualification and Certification in Nondestructive Testing
ANSI/ASNT-CP-189 ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel
NAS-410 NAS Certification and Qualification of Nondestructive Personnel (Quality Assurance Committee)
2.4 ISO Standards:
ISO 9712 Non-Destructive Testing—Qualification and Certification of NDT Personnel
3. Terminology
3.1 Definitions—For definitions of terms used in this practice, refer to Terminology E1316.
4. Significance and Use
4.1 The examination is performed by passing the tube lengthwise through or near an eddy current sensor energized with alternating
current of one or more frequencies. The electrical impedance of the eddy current sensor is modified by the proximity of the tube.
The extent of this modification is determined by the distance between the eddy current sensor and the tube, the dimensions, and
electrical conductivity of the tube. The presence of metallurgical or mechanical discontinuities in the tube will alter the apparent
impedance of the eddy current sensor. During passage of the tube, the changes in eddy current sensor characteristics caused by
localized differences in the tube produce electrical signals which are amplified and modified to actuate either an audio or visual
signaling device or a mechanical marker to indicate the position of discontinuities in the tube length. Signals can be produced by
discontinuities located either on the external or internal surface of the tube or by discontinuities totally contained within the tube
wall.
4.2 The depth of penetration of eddy currents in the tube wall is influenced by the conductivity (alloy) of the material being
examined and the excitation frequency employed. As defined by the standard depth of penetration equation, the eddy current
penetration depth is inversely related to conductivity and excitation frequency (Note 2). Beyond one standard depth of penetration
(SDP), the capacity to detect discontinuities by eddy currents is reduced. Electromagnetic examination of seamless aluminum alloy
tube is most effective when the wall thickness does not exceed the SDP or in heavier tube walls when discontinuities of interest
are within one SDP. The limit for detecting metallurgical or mechanical discontinuities by way of conventional eddy current
sensors is generally accepted to be approximately three times the SDP point and is referred to as the effective depth of penetration
(EDP).
NOTE 2—The standard depth of penetration is defined by the following equations:
SDP 5 503.3
Œ
fσ
where:
SDP = one standard depth of penetration, m,
f = frequency, Hz (cycles per second), and
σ = conductivity, Siemens/metre.
or:
SDP 5 26Œ
fσ
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 Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://dodssp.daps.dla.mil.
E215 − 22
where:
SDP = one standard depth of penetration, inches
SDP = one standard depth of penetration, in.,
f = frequency in Hz (cycles per second), and
σ = conductivity, % IACS.
5. Basis of Application
5.1 If specified in the contractual agreement, personnel performing examinations to this practice shall be qualified in accordance
with a nationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A,
MIL-STD-410, NAS-410, ISO 9712, or a similar document and certified by the certifying agency’sagency as applicable. The
practice or standard used and its applicable revision shall be specified in the contractual agreement between the using parties.
NOTE 3—MIL-STD-410 is canceled and has been replaced with NAS-410, however, it may be used with agreement between contracting parties.
5.2 If specified in the contractual agreement, NDT agencies shall be qualified and evaluated in accordance with Specification
E543. The applicable edition of Specification E543 shall be specified in the contractual agreement.
6. Apparatus
6.1 Electronic Apparatus—The electronic apparatus shall be capable of energizing eddy current sensors with alternating currents
of suitable frequencies and shall be capable of sensing the changes in the electromagnetic characteristics of the eddy current
sensors. Equipment may include a detector, phase discriminator, filter circuits, gating circuits, and signaling devices as required
for the particular application.
6.2 Eddy Current Sensors—Eddy current sensors shall be capable of inducing currents in the tube and sensing changes in the
electrical characteristics of the tube. The eddy current sensors may be of the encircling coil (annular) type or surface probe type.
7. Standardization of Apparatus
7.1 The apparatus shall be adjusted with an appropriate reference standard to ensure that the equipment is operating at the proper
level of sensitivity, with the following considerations:
7.1.1 Primary reference standards employed for this purpose shall be prepared in accordance with the methods described in
Appendix X1.1.
7.1.1.1 Other primary standards including notches may be used if agreed upon by both purchaser and supplier. Documentations
showing suitability of alternate standards should be available.
7.1.2 Equivalent secondary reference standards, prepared in accordance with methods described in Appendix X2.1, also may be
employed for standardizing the apparatus.
7.1.2.1 Other secondary standards including notches may be used if agreed upon by both purchaser and supplier. Documentation
showing suitability of alternate standards should be available.
7.1.3 Reference standards normally are of the same alloy, temper, and dimensions as the tube to be examined.
7.1.4 Examinations shall not be conducted unless the equipment can be set to the levels required by this standardization procedure.
7.1.5 For practical applications, reference standards also may be employed to establish quality control levels.
8. Procedure
8.1 Standardize the examination instrument using the appropriate reference standard prior to examination and check at least every
4 h during continuous operation, or whenever improper functioning of the examination apparatus is suspected. If improper
functioning occurs, restandardize the apparatus in accordance with Section 7, and reexamine all tubes examined since the last
successful standardization. Time between standardization can be increased based upon documented evidence of instrument stability
but shall not exceed 12 h.
E215 − 22
8.2 Tubes may be examined in the final drawn, annealed, or heat-treated temper, or in the drawn temper prior to the final anneal
or heat treatment.
8.3 The length of tube over which end effect is significant may be determined by placing a series of holes or notches in special
reference tubes and determining the distance from the tube end at which the signal amplitude from the discontinuities begins to
decrease.
8.3.1 When standardizing and testing using secondary standard Method B (X2.5.2), if full length testing is required, the tube must
be ordered to be electromagnetic tested in a rough cut length and have the untested 7 in. (175 mm) removed from each end.
NOTE 3—There is an area near each end which cannot be tested either because of an alarm from end effect or because end suppression is used to eliminate
an alarm from end effect. Up to 7 in. (175 mm) on each end is to be considered untested, regardless of the standard used. Customers must specify if they
want these untested areas removed.
9. Application
9.1 This application covers the electromagnetic examination of aluminum-alloy seamless tube using primary and secondary
reference standards.
9.2 Primary and secondary reference standards, described in Appendixes X1.1 and X2.1, respectively, when used as acceptance
standards, will establish probable detection of defects that are of a severity likely to cause leaks or substantial weakening of the
tube.
9.3 Using electronic apparatus and eddy current sensors described in Section 6, the equipment sensitivity shall be standardized
in accordance with Section 7 under the following examination conditions:
9.3.1 Frequency—The examination frequency shallshould be in the range from 1 to 125 kHz. Other frequencies or multiple
frequencies can be used if there is documented evidence of suitability for the purpose of this examination. The examination
frequency should be adjusted to provide optimum penetration of the tube wall or to place discontinuities of interest within one SDP.
Discontinuities located deeper than the SDP point will be detected with less sensitivity. The SDP point will vary as a function of
the tube alloy (conductivity) and examination frequency and may be determined by the depth of penetration equation given in
Section 4, Note 2.
9.3.2 Speed of Examination—The examination rate, or speed of the tube with respect to the eddy current sensor, may vary with
the application. In encircling coil applications, examination speeds of 50 ft/min (15 m/min) to 500 ft/min (150 m/min) are
recommended where possible, but examination speeds as high as 1000 ft/min (300 m/min) are permissible. In surface probe
applications, examination speeds are inherently slower due to reduced surface coverage and the necessity to rotate the eddy current
sensor or the tube to produce a helical scan. All instrument adjustments, that is, frequency, phase setting, filter setting, sensitivity
setting, threshold-level setting, etc., shall be made with the reference standard or acceptance standard or both passing through or
by the eddy current sensor at the same speed at which the examination of tube is to be conducted.
9.3.3 Phase Setting—The phase setting should be selected to provide the best signal-to-noise ratio for the reference standard
employed, that is, the maximum ratio of indication height from the appropriate artificial discontinuities to the indication height
from non-detrimental discontinuities.
9.3.4 Filter Setting—The filter setting should be selected commensurate with the examination speed to provide optimum filtering
of non-detrimental, time-varying discontinuities such as geometry, pathline variation, high-frequency noise, etc.
9.3.5 Sensitivity Setting—The sensitivity setting shall be adjusted to provide clearly discernible indications of a convenient height
for the appropriate accept holes (A or d ), but it shall not be high enough to cause off-scale or saturated indications for the
a
appropriate reject holes (2A or d ) of the reference standard.
b
9.3.6 Threshold-Level Setting—The threshold-level setting (reject level) shall be adjusted to automatically trigger an audio or
visual-signaling device or a mechanical marker when the appropriate artificial discontinuity (or discontinuities) of the acceptance
standard passes through or by the eddy current sensor.
E215 − 22
9.4 Using Reference Standards as Acceptance Standards:
9.4.1 Method A (X2.1) Reference Standards: When using reference standards as acceptance standards, the threshold level should
be adjusted to accept tubes exhibiting eddy current responses smaller than those obtained from the appropriate reject holes (2A or
d ) and to reject those with responses equivalent to or greater than those obtained from the appropriate reject holes (2A or d ) in
b b
the reference standard. Experience shows that this procedure will aid in the rejection of severe defects and, at the same time,
minimize erroneous rejection of tubes that might exhibit noise from non-detrimental discontinuities.
9.4.2 Method B (X2.2) Reference Standard Selection: Reference standards selected for use must be the same alloy, temper,
diameter, and wall thickness as the material being tested. The reference standard selected for use must contain the proper size reject
holes and must have been fabricated and identified in accordance with this procedure.
9.4.2.1 When using reference standards as acceptance standards, the threshold level should be adjusted as required in X2.5.2.2.
Tubes that do not exceed the alarm limits established by the reference standard shall be considered as acceptable under this method.
10. Keywords
10.1 aluminum alloy; eddy currents; electromagnetic examination; equipment standardization; NDT; nondestructive testing;
tubing
APPENDIXES
(Nonmandatory Information)
X1. PURPOSE, DESCRIPTION, FABRICATION, AND CHECKING OF PRIMARY REFERENCE STANDARDS
X1.1 Purpose
X1.1.1 Primary reference standards are used to standardize examination equipment under operating conditions to establish
acceptable limits of sensitivity, reproducibility, and capability for detecting defects of a severity likely to cause leaks or substantial
weakening of the tube.
X1.1.2 The dimensions of the appropriate primary reference standard are determined by the size of the tube to be examined. A
primary reference standard shall be a tube of the same alloy, temper, outside diameter, D, and wall thickness, t, as the tube to be
examined. This appendix covers the preparation of primary standards for test of seamless aluminum-alloy tube.
X1.2 Description
X1.2.1 The primary reference standard shall contain six artificial discontinuities in the form of flat-bottomed drilled holes in a 6-ft
(180-cm)6 ft (180 cm) length of tube which is free of significant natural discontinuities. Fig. X1.1 describes the primary reference
standard for aluminum-alloy seamless tube.
X1.2.2 The six flat-bottomed holes shall be of equal diameter, d, and shall be located in the mid-portion of the tube. The distance
between adjacent holes is 6 in. (150 mm). The minimum distance between a hole and either end of the tube shall be approximately
20 in. (500 mm).
E215 − 22
NOTE 1—Tolerance: in. 6 0.2 in. (mm 6 5 mm).
NOTE 2—All hole diameters determined by:
-3
d = × 10 (tube diameter, t) in.
-3
(d = 76.2 × 10 (tube diameter, D/wall thickness, t) mm)
NOTE 3—A holes and 2A holes are flat-bottomed and are one third the wall thickness deep and two thirds the wall thickness deep, respectively.
NOTE 4—Nominal dimensions for D and t are recommended from Table X1.1 when calculating appropriate drill diameters for tubes having D/t ratios
that result in hole sizes outside the standard drill size range of No. 1 to No. 80.
FIG. X1.1 Primary Reference Standard for Seamless Aluminum-Alloy Tube
X1.2.3 Three of each of the reference standard holes A and 2A shall be drilled consecutively to depths of one third and two thirds
the wall thickness, respectively in radial longitudinal planes 120 6 5° apart.
X1.2.4 The diameter, d, of the flat-bottomed drill used to make a primary reference standard hole shall be determined
mathematically with the following equation:
d 5 k D/t 310 (X1.1)
~ !
where:
d = drill diameter of A and 2A flat-bottom holes, in. (mm),
k = 3.0 in. (76 mm),
D = tube outside diameter, in. (mm), and
t = tube wall thickness, in. (mm).
X1.2.5 In computing the appropriate drill diameters, it is recommended that the nominal dimensions for D and t listed in Table
X1.1 be used for tubes having heavy or very thin wall thicknesses or outside diameter-to-wall thickness ratios that calculate to drill
sizes outside the standard drill size range of gage No. 1 to gage No. 80. The dimensions D,t, and d must be expressed in the same
units of measurement, that is, inches or millimetres when calculating the appropriate drill diameters.
X1.2.6 A standard drill size (drill gage between No. 1 and No. 80 inclusive) nearest the calculated drill diameter, d, may be
employed for drilling the hole size required.
X1.3 Identification
X1.3.1 Each primary reference standard shall be clearly marked within the first 2 in. (50 mm) from the end of the tube adjacent
to the 2A holes. The standard shall be marked in a manner that provides rapid identification of the manufacturer, outside diameter,
wall thickness, identifying number, alloy, and temper. Permanent identification shall be accomplished by a method not harmful to
the tube.
E215 − 22
TABLE X1.1 Applicable Primary and Secondary Standard Nominal Dimensions and Drill Sizes for Various Ranges of Tube Sizes
Inch-Pound, in.
Tube Size Nominal Standard Dimensions Drill Size
Wall
Primary Secondary
Dia.,
Outside Diameter Thickness,
D ± 10 %
Dia., d Dia., d Dia., d
a b
t ± 10 %
#0.0625 to 0.125 0.0938 0.015 0.023 0.010 0.015
>0.125 to 0.250 0.1875 0.022 0.026 0.013 0.019
>0.250 to 0.375 0.3125 0.035 0.027 0.014 0.020
>0.375 to 0.500 0.4375 0.049 0.027 0.014 0.020
>0.500 to 0.625 0.5625 0.049 0.034 0.018 0.027
>0.625 to 0.750 0.6875 0.049 0.042 0.021 0.032
>0.750 to 1.000 0.8750 0.049 0.054 0.028 0.042
>1.000 to 1.250 1.125 0.058 0.058 0.030 0.045
>1.250 to 1.500 1.375 0.058 0.071 0.036 0.055
>1.500 to 1.750 1.625 0.067 0.073 0.038 0.057
>1.750 to 2.000 1.875 0.067 0.083 0.043 0.065
>2.000 to 2.500 2.250 0.076 0.089 0.046 0.069
>2.500 to 3.000 2.750 0.083 0.099 0.051 0.077
>3.000 to 3.500 3.250 0.095 0.103 0.053 0.080
>3.500 to 4.000 3.750 0.095 0.118 0.061 0.092
SI Units, mm
Wall Primary Second
Outside Diameter Dia., D
Thickness, t Dia., d Dia., d Dia., d
a b
#1.59 to 3.18 2.38 0.38 0.58 0.25 0.38
>3.18 to 6.35 4.76 0.56 0.66 0.33 0.48
>6.35 to 9.53 7.94 0.89 0.69 0.36 0.51
>9.53 to 12.70 11.11 1.24 0.69 0.36 0.51
>12.70 to 15.88 14.29 1.24 0.86 0.46 0.69
>15.88 to 19.05 17.46 1.24 1.07 0.53 0.81
>19.05 to 25.40 22.23 1.24 1.37 0.71 1.07
>25.40 to 31.75 28.58 1.47 1.47 0.76 1.14
>31.75 to 38.10 34.93 1.47 1.80 0.91 1.40
>38.10 to 44.45 41.28 1.70 1.85 0.97 1.45
>44.45 to 50.80 47.63 1.70 2.11 1.09 1.65
>50.80 to 63.50 57.15 1.93 2.26 1.17 1.75
>63.50 to 76.20 69.85 2.11 2.51 1.30 1.96
>76.20 to 88.90 82.55 2.41 2.62 1.35 2.03
>88.90 to 101.60 95.25 2.41 3.00 1.55 2.34
X1.3.2 As a further means of identification, the primary reference standard may be anodized and dyed. This anodizing and
coloring provides positive identification and a wear-resistant surface and does not affect the eddy current response characteristics
of the primary reference standard. Caution should be exercised to maintain a uniform anodic coating along the entire length of the
tube because boundaries between anodized and unanodized areas may appear as discontinuities during testing.
X1.4 Fabricating Procedure
X1.4.1 The fabricating procedure includes cutting the tube to length, locating and drilling the flat-bottomed holes, deburring and
finishing the sawed ends, and identifying the tube as prescribed by X1.3. The use of a jig with suitable interchangeable drill
bushings is recommended for drilling the flat-bottomed holes.
X1.4.2 The original outside and inside surfaces of the tube shall be retained without any mechanical refinishing. Care must be
taken to avoid dents, abrasions, and other conditions that mar the surface or distort the contour of the tube wall.
X1.4.3 The holes shall be drilled with flat-bottomed drills which are flat to within 2 % of the hole diameter. The drills must meet
recognized manufacturers’ tolerance for wire-sized drills. The hole depth shall be measured from the outside diameter of the tube
to the bottom of the hole along the radial centerline through the hole. Hole depths must be held to within 60.001 in. (60.025 mm)
of the specified depths. A scribe or vibrating pencil should be u
...