ASTM E1961-98

Standard Practice for Mechanized Ultrasonic Examination of Girth Welds Using Zonal Discrimination with Focused Search Units

SCOPE
1.1 This practice covers the requirements for mechanized ultrasonic examination of girth welds. Evaluation is based upon the results of mechanized ultrasonic examination. Acceptance criteria are based upon defect limits defined by an Engineering Critical Assessment (ECA) or other accept/reject criteria defined by the Contracting Agency.
1.2 This practice shall be applicable to the development of an examination procedure agreed upon between the users of this practice.
1.3 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.4 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.

General Information

• Status: Historical
• Publication Date: 09-Jul-1998
• ICS: 25.160.40 - Welded joints and welds
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.06 - Ultrasonic Method

Relations

• Replaced By: ASTM E1961-98(2003)e1 - Standard Practice for Mechanized Ultrasonic Examination of Girth Welds Using Zonal Discrimination with Focused Search Units
• Effective Date: 10-Jun-2003
• Referred By: ASTM E2373/E2373M-19 - Standard Practice for Use of the Ultrasonic Time of Flight Diffraction (TOFD) Technique
• Effective Date: 10-Jul-1998
• Referred By: ASTM E543-21 - Standard Specification for Agencies Performing Nondestructive Testing
• Effective Date: 10-Jul-1998

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 1961 – 98
Standard Practice for
Mechanized Ultrasonic Examination of Girth Welds Using
Zonal Discrimination with Focused Search Units
This standard is issued under the fixed designation E 1961; 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 2.4 Military Standard:
MIL-Std-410 Nondestructive Testing Personnel Qualifica-
1.1 This practice covers the requirements for mechanized
tion and Certification
ultrasonic examination of girth welds. Evaluation is based
2.5 API Standard:
upon the results of mechanized ultrasonic examination. Accep-
API STD–1104 Welding of Pipeline and Related Facilities
tance criteria are based upon defect limits defined by an
2.6 CSA Standard:
Engineering Critical Assessment (ECA) or other accept/reject
CSA Z-662 Oil and Gas Pipelines Systems
criteria defined by the Contracting Agency.
1.2 This practice shall be applicable to the development of
3. Terminology
an examination procedure agreed upon between the users of
3.1 Definitions:
this practice.
3.1.1 Definitions relating to ultrasonic examination, that
1.3 The values stated in SI units are to be regarded as the
appear in Terminology E 1316 shall apply to the terms used in
standard. The inch-pound units given in parentheses are for
this practice.
information only.
3.2 Definitions of Terms Specific to This Standard:
1.4 This standard does not purport to address all of the
3.2.1 acceptance criteria—definition of acceptable/
safety concerns, if any, associated with its use. It is the
rejectable defects as defined by an Engineering Critical Assess-
responsibility of the user of this standard to establish appro-
ment (ECA), such as defined in CSA-Z662 or API 1104, or
priate safety and health practices and determine the applica-
workmanship criteria as defined by the contracting agency.
bility of regulatory limitations prior to use.
3.2.2 contract document—any document specified in the
2. Referenced Documents contract between the contracting agency and contractor, includ-
ing the purchase order, specification, drawings or other written
2.1 The following documents form a part of this practice to
material.
the extent specified herein:
3.2.3 contracting agency—a government agency, prime
2.2 ASTM Standards:
contractor or subcontractor procuring ultrasonic examination
E 164 Practice for Ultrasonic Contact Examination of Weld-
services.
ments
3.2.4 contractor—the nondestructive examination contrac-
E 317 Practice for Evaluating Performance Characteristics
tor engaged by the contracting agency in work covered by this
of Pulse-Echo Testing Systems Without the Use of Elec-
practice.
tronic Measurement Instruments
2 3.2.5 mapping type presentations—an ultrasonic image pre-
E 1316 Terminology for Nondestructive Examinations
sentation whereby the digitized A-scan signal is represented as
2.3 ANSI/ASNT Standards:
colors or grayscale for amplitude variation along one axis
ASNT Practice SNT-TC-1A Personnel Qualification and
representing time of flight and the other axis is the sampling
Certification in Nondestructive Testing
position, or the distance along the weld.
ANSI/ASNT-CP-189 Standard for Qualification and Certi-
3.2.6 operator(s)—the term “operator(s)” as used in this
fication of Nondestructive Testing Personnel
practice shall mean the operator(s) of ultrasonic equipment
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde-
structive Testing and is the direct responsibility of Subcommittee E07.06 on Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
Ultrasonic Method. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS
Current edition approved July 10, 1998. Published September 1998. Available from American Petroleum Institute, 1220 L Street, Northwest,
Annual Book of ASTM Standards, Vol 03.03. Washington, DC 20005.
3 6
Available from American National Standards Institute, 11 W. 42nd St., 13th Available from Canadian Standards Association, 178 Rexdale Boulevard,
Floor, New York, NY 10036. Etobicoke, Ontario, Canada M9W 1R3.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1961–98
who is (are) certified according to the requirements in 6.6 and procedure. This examination should be combined with scribing
at a level deemed acceptable to the contracting agency. the reference line as described in 9.3.
5.1.2 Any items of non-compliance shall be referred to the
4. Significance and Use contracting agency representative for corrective action.
5.2 Ultrasonic Examination—All girth welds identified for
4.1 This practice is intended primarily for the mechanized
mechanized ultrasonic examination should be examined for
ultrasonic examination of pipe girth welds used in the con-
100 % of their circumference and assessed in accordance with
struction of gas and oil pipelines. This practice, with appropri-
the contracting agency’s acceptance criteria. Examination
ate modifications due to changes in weld profile, may also be
should be conducted in accordance with procedures approved
used to examine repaired welds. Manual techniques such as
by the contracting agency.
described in Practice E 164 may also be used to examine
production or repaired welds. This practice, with appropriate
modifications, may also be used to examine other forms of butt 6. Ultrasonic Equipment
welds including long seams.
6.1 Ultrasonic System—The system shall provide an ad-
4.2 Techniques used are to be based on zonal discrimination
equate number of examination channels to ensure the complete
whereby the weld is divided into approximately equal vertical
volumetric examination of the weld through thickness in one
examination sections (zones) each being assessed by a pair of
circumferential scan. The instrument should provide a linear
ultrasonic search units. See Fig. 1 for typical zones.
“A” scan presentation for each channel selected. The exami-
4.3 Thicknesses of material examined are normally 7 to 25
nation channels will allow the volume of the weld scanned to
mm (0.28 to 1.00 in.) and pipe diameters 15 cm (6.0 in.) and
be assessed in accordance with the examination zones as
greater but this standard may apply to other thicknesses and
typically defined in Fig. 1. Instrument linearity should be
diameters if the techniques can be proven to provide the
determined according to the procedures detailed in Practice
required zonal discrimination.
E 317, within six months of the intended end use date. The
4.4 Examination zones are typically 2 to 3 mm (0.08 to 0.12
contractor shall retain a copy of the calibration certificate.
in.) in height. For most applications this will require the use of
Instrument linearity should be such that the accuracy of any
contact focused search units to avoid interfering signals origi-
indicated amplitude is within 5 % of the actual full scale
nating from off-axis geometric reflectors and to avoid exces-
amplitude. This should apply to both linear and logarithmic
sive overlap with adjacent zones.
amplifiers. Each examination channel should be selective for:
pulse-echo or through-transmission mode, gate position and
5. Examination Methods
length for a minimum of two gates, and gain. Recording
5.1 Visual Examination—All welds should be visually ex- thresholds should be selectable to display signals between 0
amined after completion and assessed in accordance with the and 100 % of full screen height for simple amplitude and
requirements of surface conditions for ultrasonic examination. transit time recording and should be from 0 to 100 % for
5.1.1 All bevels should be examined immediately after B-scan or “mapping” type recording of data. Two recordable
machining to ensure compliance with the applicable welding signal outputs per gate should be available, being either analog
FIG. 1 Schematic Representation of Weld Zones and Discontinuities
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E1961–98
or digital and representative of signal height and time of flight. for field examination and to monitor the system’s performance
These will be suitable for recording on a multi-channel on an ongoing basis. Reference standards shall be manufac-
recorder or computer data acquisition software display. tured from a section of unflawed project-specific line pipe
6.2 Recording System: supplied by the contracting agency. The contracting agency
6.2.1 A distance measuring circuit or device suitable for will provide the contractor with details of project-specific weld
connection to the recorder or acquisition system shall provide geometries and the reference reflectors required in specific
a means of electronically determining circumferential weld areas. The contractor shall then provide a reference standard
distance to an accuracy of typically 6 1 cm (0.4 in.) or better, design that must be submitted to the contracting agency for
as required by the contracting agency, over the circumference approval before manufacturing. No design changes to the
of the weld (an optical encoder is typically used for such reference standard shall be made without prior approval of the
distance measurement). Programmed scan lengths shall be contracting agency. Annex A3 provides an example of a typical
sufficient to ensure all probes will travel the maximum circum- reference standard.
ferential distance required for a pipe having a diameter with the 6.6 Personnel Qualification—If specified in the contractual
maximum tolerance allowed by the contracting agency’s speci-
agreement, personnel performing examinations to this practice
fication. For equipment with encoders traveling on a track or shall be qualified in accordance with a nationally recognized
welding guide-band a correction factor will be incorporated to
NDT personnel qualification practice or standard such as
ensure the circumferential distance recorded on the chart ANSI/ASNT-CP-189, SNT-TC-1A, MIL-STD-410, or a simi-
corresponds to the search unit position on the pipe outer
lar document and certified by the employer or certifying
surface. The recording or marking system shall clearly indicate agency as applicable. The practice or standard used and its
the location of discontinuities relative to the marked starting
applicable version shall be identified in the contractual agree-
position of the scan, with a 6 1 cm (0.4 in.) accuracy. There
ment between the using parties.
shall be recordings from each search unit for weld discontinui-
6.7 Ultrasonic Examination Procedure—The contractor
ties and confirmation of the acoustic coupling arranged on the
should provide a procedure that will provide examination
chart or display in a manner acceptable to the contracting
criteria for the ultrasonic examination of the weld in a single
agency.
pass. It must allow for characteristic Hi/Lo fit-ups (edge
6.2.2 B-scan or other form of “mapping” displays will be
misalignment), weld shrinkage and be pipe size specific.
used for volumetric flaw detection and characterizations and
Procedures submitted will allow zonal defect characterization
Time of Flight Diffraction (TOFD) techniques may be added to
that permits use of the contracting agency’s engineering critical
improve characterization and sizing. TOFD techniques may
assessment acceptance criteria. It should include but not be
augment pulse-echo techniques but shall not replace pulse-
limited to describing the following requirements:
echo techniques.
6.7.1 The mechanized variable speed scanner mountable on
6.2.3 Where TOFD techniques are employed the recording
mechanical welding bands or other tracking mechanism,
system should be capable of a 256-level grayscale display and
6.7.2 The encoder capable of accurately indicating any
be capable of recording full R-F wave forms for the TOFD
defect location about the girth weld,
search unit pairs.
6.7.3 Independently loaded ultrasonic search units mounted
6.3 Coupling—The coupling shall be obtained by using a
in an array that provides independent examination of the weld
medium suitable for the purpose. An environmentally safe
from both sides,
wetting agent may be required to enhance acoustic coupling.
6.7.4 Provisions for adjusting and maintaining the align-
No residue should remain on the pipe surface after the liquid
ment of these search units,
has evaporated. For examination where ambient temperatures
6.7.5 Provisions for recording the continuity of the cou-
are below 0°C (32°F) a methyl alcohol washer fluid or a similar
pling,
medium may be used. This liquid medium may be recovered
6.7.6 Provisions for ensuring the mechanical reliability of
and filtered for re-use. For examination where pipe cool-down
the equipment,
may be required after welding, water spray or other agents may
6.7.7 A technique summary stating beam angles, wave
be used with contracting agency approval.
types, search unit frequencies, beam sizes and profiles with
6.4 Search Units:
sketches for each geometry to be examined,
6.4.1 Each search unit shall be marked with a method to
6.7.8 Record analog or digital signals from the multi-
identify the manufacturer’s name, search unit type, exit point,
channels to a common distance of rotation,
incident beam angle or refracted beam angle for a specific
6.7.9 Provide permanent copy of the scans in an easily
wedge/steel velocity ratio, frequency, and crystal size.
interpretable format to meet archival and audit needs,
NOTE 1—For phased array and EMAT probes, not all of the listed items
6.7.10 Provide construction and accuracy details of the
may be applicable.
reference standard,
6.4.2 The search unit array design shall be specific to the 6.7.11 Provide the standardization procedures to be used in
the field, and
project where the examination is to be performed.
6.4.3 All search units shall be contoured to match the 6.7.12 Standardization checks should be established and
curvature of the pipe surface. verified on a time or weld cycle defined by the contracting
6.5 Reference Standards—Reference standards shall be agency. System performance between standardization checks
used to establish sensitivity and qualify the examination system should be continually monitored for degradation.
NOTICE: This st
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