Appendix F Phased Array Ultrasonic Testing The following is prepared in accordance with the AWS D1.1 Code 2010 edition in order to conduct phased array examinations to detect fabrication and field welding flaws in welded steel pipe. A phased array ultrasonic testing procedure shall be written and qualified in accordance with the requirements herein. Essential variables detailed in Attachment A and shall be addressed in the phased array ultrasonic testing procedure. 1.0
Purpose The purpose is to outline the requirements for phased array examinations of carbon steel pipe welds.
2.0
Scope Carbon steel complete penetration (CJP) joint welds with or without backing bar shall be examined in accordance with these requirements to include thicknesses of 0.25 inches to 2.0 inches.
3.0
References 3.1 3.2 3.3 3.4 3.5
4.0
AWS D1.1, 2010 Edition ASNT SNT-TC-1A CP-189 2011 Edition CP-105 2011 Edition ASTM E 2700-09
Personnel Training and Qualification Requirements 4.1
All PAUT personnel shall be trained and certified in accordance with ASNT SNT-TC-1A, 2011 Edition.
4.2
Personnel conducting PAUT examinations and evaluating results obtained shall be certified to Phased Array Ultrasonic Level II or Level III, in accordance with reference 3.3 as a minimum.
4.3
All PAUT Level II and III personnel shall have attended a minimum of 80 hours of documented Phased Array Training in accordance with ASNT CP-105, 2011 Edition.
4.4
Certified Ultrasonic UT Level I and UT Level II personnel that have been trained in the use of the equipment and have demonstrated the ability to properly acquire examination data to a saved setup file shall be allowed to conduct examinations while under the direct supervision of a certified PAUT Level II or Level III, but shall not be allowed to interpret the results obtained. This individual is considered a “Scanner Technician” or an assistant to the certified PAUT Level II. Calibration, setup and data acquisition shall only be conducted by a certified PAUT Level II.
1
5.0
4.5
Phased Array Level II and III personnel shall pass a specific written examination of 30 questions minimum of the Phased Array procedure to be implemented.
4.6
In addition, under the guidelines of Attachment B, Performance Demonstration Qualification (PDQ) Examinations shall be successfully completed in order to implement the Phased Array Examination in accordance with the requirements herein.
Phased Array Definitions 5.1
Active Aperture: The number of elements in a Phased Array Transducer used for the examination.
5.2
Angle Corrected Gain, ACG: This is compensation for the variation in signal amplitudes during S-scan calibration at swept angles. The compensation is typically performed electronically at multiple depths. A set of gain values is applied to each summed A-scan presentation during angular electronic scanning in order to get the same amplitude level for echoes reflected by a specific target, whatever the refracted angle or depth. Note that there are technical limits to ACG, that is, beyond a certain angular range, compensation is not always possible.
5.3
Automated Scanner: An encoded, mechanical, motorized device for scanning along welds to collect data. If the scanning device is manually driven but encoded, it is called a semi-automated scanner.
5.4
E-scan, also called a linear scan: In this scan multiple elements groups are excited using the same focal laws so as to form a single beam angle and this same beam angle is indexed along the phased array probes active aperture.
5.5
Encoder: A device that records probe position for computer analysis.
5.6
Focal Law: A phased array operational file defining search unit elements and time delays for transmitted and received signals.
5.7
Line scan: The phased array scan technique in which an E, S or combination scan is performed with the beams directed perpendicular to the weld, at a fixed distance from the welds in a manner demonstrated to provide full weld coverage.
5.8
PAUT: Phased Array Ultrasonic Testing.
5.9
Pitch: The center to center distance between two successive phased array transducer elements.
5.10
S-scan, also called a sectorial scan: In this scan a single group of elements is excited using multiple focal laws to form a series of different beam angles emanating from the same group of elements.
5.11
S-view: The phased array instrument view that displays accumulated A-scan information in a sector or volume of material. The sector display is used for both E-scan and S-scan data.
5.12
Scan Plan: A document specifying key process elements such as equipment detail, focal law settings and probe positions as necessary to complete an
2
examination also depicting weld coverage.
6.0
5.13
Depth Calibration: A specific action used to compensate and adjust instrument time delay over all focal laws (angles of refraction) for a specific wedge geometry for depth calibration.
5.14
Virtual Probe Aperture, VPA: The grouping of elements in a given set of elements to be fired in a Linear Scan.
Phased Array Equipment 6.1
The ultrasonic phased array system shall include: • A phased array test instrument as detailed herein. • Phased array probe or probes as detailed herein as defined in the Scan Plan • Encoding System Scanner, Wheel, or String
6.2
Automated or semi-automated scanners, as specified in the Scan Plan, shall be performed using a pulse-echo technique using an Olympus OmniScan or equal PAUT instrument. This PAUT System shall be qualified in accordance with the PDQ Procedure Qualification (PQ) program and meet the following performance requirements. 6.2.1
As a minimum, the Phased Array unit shall have a gain control adjustable in increments of 1 or 2 dB steps and over a range of at least 60 dB.
6.2.2
The instrument shall be suitable for use with transducers which generate frequencies over a minimum range of 2 to 6 MHz. Other Phased Array probe frequencies maybe used if approved by the PAUT Level III.
6.2.3
The instrument shall be capable of producing sectorial, S-Scans or Electronic, E-scans or a combination of both S and E-Scans as defined by the Scan Plan.
6.2.4
The instrument shall be equipped with a minimum of 16 pulsers and channels (16:16 minimum). A minimum of 16:64 is required if E-scans are to be used.
6.3
In addition to the phased array system, peripherals such as keyboard, mouse and data storage devices may be used in calibration, set-up and reporting. Subsequent to data collection completion, data-analysis personnel may use a personal computer with optional data analysis tools and display software for analyzing data.
6.4
Straight-Beam, Longitudinal Wave Search Units 6.4.1
The straight beam search unit may be of a conventional or phased array type.
6.4.2
Conventional transducers shall be square or round, have an active area of at least 1/2 square inches and no more than 1 square inch, and operate at frequencies between 2 and 2.5 MHz.
3
6.4.3
6.5
Angle-Beam, Shear Wave Search Units 6.5.1
6.6
6.8
6.7.1
The wedge shall produce refracted shear waves in the material being tested within +/- 2 degrees of the minimum and maximum angle used or +/- 2 degrees of the first and last VPA for E-scans.
6.7.2
Nominal shear wave refracted wedge angles between 45º and 70º shall be used to ensure coverage of the weld and heat affected zone, HAZ. When a refracting wedge is used, the phased array generated angles shall be within the useful range of the wedge. The refracted angles shall be detailed in the appropriate Scan Plan for the configuration in accordance with the requirements of paragraph 9.0 herein.
Encoder For angle beam Phased Array Examinations, encoding in accordance with the requirements herein shall be linear digital encoder capable of line scanning and may be semi-automatic or automatic type.
Couplant 6.9.1
6.10
The Phased Array probe shall be a linear array type consisting of 16 or more elements (64 or more if E-scans are to be used) and produce frequencies between 2 and 6 MHz. The total aperture size, active and passive, may be any size down to 3/8 inch provided the element size and pitch are suitable to prevent grating lobes or other unsuitable noise.
The Phased Array Wedge
6.8.1
6.9
Angle-beam search units shall consist of a phased array probe and an angle wedge to produce the desired refracted angles. The phased array angle beam wedge shall produce refracted shear waves between 45 and 70 degrees. Other angles may be used to increase weld volume coverage if qualified in accordance with this requirements herein.
Phased Array Probe 6.6.1
6.7
Phased Array Straight beam probes shall have an active aperture no less than 0.375 inches, and shall operate at frequencies between 2 and 6 MHz.
Unless otherwise stipulated in the Scan Plan, any commercial couplant, water, or oil may be used as couplant when performing calibrations and examinations. Couplant used for examination of production welds shall be the same couplant used during calibration.
Calibration Blocks 6.10.1 Calibration for Phased Array Examinations shall be in accordance with the requirements of paragraph 9 herein. The calibration reflector shall be a 1.5mm (0.060”) side drilled hole or equivalent. A suitable amount of calibration reflectors shall be placed in any design of calibration block, weld mock-up or actual production part at the option of the user to cover the entire sound path range to be inspected. An example of a basic calibration block is shown in Figure 2 except that multiple reflectors will
4
likely be necessary to allow proper calibration of phased array configurations. 6.10.2 Block Material: When blocks are used, they shall be made of essentially the same material type and heat treat as the material being examined. The block thickness shall be essentially the same as the material being examined. 6.10.3 Weld Mock-Up and Production Parts: Alternate possible uses of the reflector are shown in Figure 3. When weld mock-ups and sections of production weldments are used, the reflector shall be in locations where it is difficult to direct sound beams, thereby ensuring detection of discontinuities in all areas of interest. 6.10.4 Corner reflectors shall not be used for calibration purposes. 6.10.5 Alternate Blocks: An International Institute of Welding (IIW) block, Phased Array Calibration Standard (PACS ®) or other blocks of similar material may be used to aide in calibration where necessary.
FIGURE 1 CALIBRATION STANDARD
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FIGURE 2 ALTERNATE CALIBRATION STANDARDS 7.0
Phased Array Instrument Linearity 7.1
Linearity verifications shall be conducted every 30 days and recorded. • Horizontal Linearity • Display Height Linearity • Amplitude Control Linearity
8.0
9.0
Phased Array Element Operability 8.1
An element operability check shall be performed before initial calibration and use, and weekly on each phased array probe to determine if dead or inactive, or defective elements are present. No more than 10 percent of the elements shall be dead and in a given aperture, and no more than two adjacent elements shall be dead within a given aperture.
8.2
In addition, each phased array element shall be evaluated for relative amplitude within the aperture and shall be verified to be within 6 dB of the average amplitude of the other elements. If the amplitude is outside the 6 dB requirement, then the probe element shall be declared dead.
Scan Plan Development 9.1
A Scan Plan examination strategy shall be developed for all weld joint configurations. This Scan Plan requires consideration of each weld or group of welds of the same essential geometry, thickness and configuration through preparation of a Scan Plan. The Scan Plan details specific attributes necessary to achieve examination coverage including those variables subject to material and geometric variation that are not addressed in a general procedure. (Figures 5 and 6 contain typical Scan Plans with Index Offsets, these Scan Plans are for information only and not intended for use.)
6
9.2
The Scan Plan shall demonstrate by plotting or computer simulation the appropriate refracted angles to be used during the examination for the weld prep angles and areas of concern. The Scan Plan shall demonstrate coverage of the required examination volume.
9.3
Caution should be taken when using computer modeling programs and drafted sketches to demonstrate coverage. The true measure of performance as envisioned must be verified through the calibration, that is, beam index point and beam angle verifications.
9.4
Whenever a Scan Plan is developed, parameters shall be defined and validated by the Scan Plan developer (PAUT Level II or III) by performing the initial calibration to optimize those parameters. A new calibration is required if the Scan Plan developer determines or suspects that an essential variable has changed.
9.5
The Scan Plan shall be documented to show the examination volume examined and shall be a part of the final examination report. Scan Plan contents shall consider all applicable essential and non-essential variables as detailed in Attachment B.
9.6
A detailed Scan Plan shall be established for each weld type, joint design and thickness.
9.7
Phased Array Scan Configuration
9.8
9.7.1
S-Scans shall be used as the primary scan to optimize coverage to fully examine the weld and HAZ in accordance with the approved Scan Plan.
9.7.2
An unfocused (naturally focused) sound beam shall be configured for scanning. Focusing may be used to better define and dimension the length and through wall height of a given flaw, but shall not be used during evaluation for acceptance.
9.7.3
E-Scans may be used to supplement the S-Scans for single sided access welds and different weld joint configurations to ensure complete coverage of the weld and HAZ, or to provide specific joint geometry coverage of the weld bevel, for example T joint welds.
9.7.4
When multiple E-Scans are used to provide coverage, a 10 percent overlap shall be specified in the Scan Plan. When S and E-Scans are used in combination, similar overlaps shall be used.
9.7.5
Multiple groups may be used to establish combinations of phased array configurations.
9.7.6
When S-Scans are used, two different S-Scan index positions from both sides of the weld shall be specified in the Scan Plan to provide the required angle beam coverage of the weld and heat affected zone.
The parameters for phased array examination are addressed as either essential or non-essential variables and are listed in Attachment A. All essential variables shall be demonstrated during the PDQ PQ qualification.
7
9.9
When procedure qualification is required, any changes to a variable listed as essential in shall require requalification.
9.10
The Scan Plan shall demonstrate full ultrasonic coverage in two crossing directions to cover the full weld volume, including weld bevel coverage within plus or minus 10 degrees of perpendicular (90 degrees to the weld fusion face), and HAZ coverage. Butt joints shall be tested from each side of the weld axis.
9.11
Some weld joint geometries, such as tee or corner joints, may not allow phased array examinations from both sides of the weld. A combination of S-Scans and E-Scans may demonstrate full coverage of the weld from only one side.
9.12
In addition, for corner or tee joint welds, the weld may be examined with a straight beam or low angle longitudinal waves from the face opposite the weld to aide in obtaining coverage requirements.
9.13
Welds that cannot be examined from at least one side using the angle beam technique shall be noted in the examination report.
9.14
Overlap between adjacent active apertures, that is aperture incremental change, shall be a minimum of 50 percent of the aperture height.
9.15
Welds shall be examined for transverse flaws which may be performed by a nonencoded manual phased array or conventional ultrasonic technique. Welds without reinforcement shall be scanned directly over the weld area. Welds with reinforcement shall be scanned by positioning the search unit within 15 degrees parallel to the weld joint using a conventional or a Phased Array Probe.
9.16
Scan Plan parameters shall be stored on the phased array system storage and shall be backed up on alternate media. These basic parameters are the starting point for all calibrations that follow.
9.17
Each Scan Plan shall detail the PA Instrument and PA Probe make and model, including the angles of refraction and the index positions.
9.18
A minimum of two index positions from both sides of the weld shall be used to ensure weld volume coverage. 9.18.1 Skew Angles of 90-1, 90-2 and 270-1 and 270-2 9.18.2 See examples below in Figures 5 and 6
9.19
If the weld-root opening changes by more than 3/16 inch, a new scan plan shall be developed to ensure PA coverage of the weld and HAZ.
9.20
If the material thickness deviates from the Scan Plan Design thickness by more than 0.060 inches in thickness, then a new Scan Plan shall be developed to ensure weld volume coverage in according to the requirements herein.
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10.0
Phased Array Calibration and Set-up 10.1
Ultrasonic equipment used shall be calibrated for testing just before examination of the completed weld. Verification of calibrations shall be performed after each inspector change, at two hour testing intervals or when the electrical circuitry is disturbed, including the following: 1. Transducer change 2. Battery change 3. Electrical power change 4. Coaxial cable change 5. Power failure All calibrations shall be performed with the reject or suppression control turned off.
10.2
Straight Beam Calibration. Straight beam calibration shall be performed with the search unit, meeting the requirements of paragraph 6.4. For Phased Array straight beam examinations a wedge delay calibration is recommended but not required unless evaluations of indications are being performed. 10.2.1 Adjust the distance range controls to show the equivalent of two plate thicknesses for the weld to be examined. The gain or sensitivity shall be adjusted in an area of the plate free from any indications so that the first back reflection is at 50 percent of full screen height, FSH.
10.3
Angle Beam Calibration – Phased Array angle beam Probes shall meet the requirements of paragraph 6.4 and 6.5.
10.4
True Depth calibration shall be performed before sensitivity calibration for each angle or VPA used during the inspection. This calibration may be performed on a radius from a standard IIW, Type 1 or 2 block or side drilled hole.
10.5
Sensitivity Calibration shall be performed on a side drilled hole at a depth coinciding with the first point of the TCG calibration.
10.6
Beam index points shall be identified for instruments which cannot plot the location of indications to the front of the phased array probe. A minimum of three points evenly spaced throughout the utilized angles or VPAs shall be identified along the active aperture.
10.7
Refracted Angle. The minimum and maximum angle, each VPA for E-Scans, utilized during the inspection shall be verified to be within +/- 2 degrees of the actual angle configured.
10.8
Final Range Setting. As a minimum, the PAUT Screen range shall be adjusted to view the entire sound-path range or material depth to be tested at all angles used. As a general rule of thumb, range may be configured as three times the material thickness at the minimum angle to be used during the examination. The range settings shall be controlled by the Scan Plan developed for the specific PAUT examinations and index offset.
9
10.9
A Time Corrected Gain (TCG) Line shall be established throughout all inspection angles or VPAs on a calibration block as detailed in Paragraph 6.8. A minimum of three calibration points shall be used to cover the entire range to be tested. All points should be electronically adjusted to +/- 5 percent of a set screen height at 50 percent of FSH. The dB gain at which the TCG Line is established is identified as the Standard Sensitivity Level, SSL, unless transfer correction, as detailed below, is required.
10.10
Using the basic calibration block establish a reference amplitude signal. This signal shall be established at 50 percent full screen height, FSH. This is the Standard Sensitivity Level, SSL. See Table 1 for the additional reference and acceptance/rejection criteria.
10.11
Using an OmniScan MX-2 or equal), establish two additional TCG lines as follows: • • •
A – 6 dB line (DRL) shall be established at 25 % FSH A + 5 dB line (ARL) shall be established at 98 % FSH See Figure 3 below
ARL + 5dB 98 % FSH
SSL 50% FSH
DRL ‐ 6dB 25% FSH
Figure 3 11.0
Phased Array Examination and Data Acquisition 11.1
All inspection surfaces that the PA Probe is applied to shall be free of dirt, grease, oil, loose scale, paint or weld spatter and shall have a surface contour that permits adequate coupling. A couplant, for example water, shall be used between the transducer and the inspection surface on all scans.
11.2
The entire base metal that the ultrasound will pass shall be examined for laminar reflectors using a straight beam transducer that meets the requirements of
10
paragraph 6.4. During this examination a thickness measurement shall be conducted to document the actual thickness of the pipe to be examined. This thickness shall be documented in the Phased Array instrument to ensure correct “Part” thickness. 11.3
Any base metal areas that exhibit a total loss of back reflection or an indication equal to or greater than the back reflection that would interfere with the subsequent angle beam inspection shall have its location determined relative to Face A and noted on the inspection report. An alternative inspection scanning procedure shall be used as follows:
11.4
For discontinuities larger than the aperture of the PA Probe, a full loss of the back reflection may occur. The discontinuity edges may be located by moving the transducer until a 6 dB loss is noted from the back reflection and using the transducer centerline as the discontinuity edge. For discontinuities smaller than the transducer, the discontinuity edge is found by moving the transducer toward the discontinuity until an indication in noted on the screen. The leading edge of the PA probe Wedge is used as the discontinuity edge.
11.5
If part of a weld is inaccessible due to laminar content, the location and depth of the lamination(s) shall be noted in the final test report.
11.6
Shear Wave Inspection. An angle beam transducer unit that meets the requirements of paragraphs 6.4 and 6.5 shall be used to inspect welds. Equipment shall be calibrated in accordance with paragraph 10.
11.7
Automated computer data acquisition and recording of essential ultrasonic data in the manner of linear scans, or line scans shall be performed down the length of each weld. Scanning shall be performed in accordance with the documented and approved Scan Plan as detailed in paragraph 9.
11.8
Scanning shall be performed at a minimum of 6 dBs above the SSL as established in paragraph 10. When a TCG is utilized, scanning may be performed at reference dB level, provided soft gain or color pallet alterations are made during analysis to aid in evaluation.
11.9
For line scanning using an encoder, limitations on scan speed are dictated by the equipment. The indicated speed of acquisition developed for the given setup shall not be exceeded. Exceeding this speed will cause data dropout. If data dropout is noted, it shall not exceed 1 percent of the recorded data and no two consecutive lines of data shall be missed.
11.10
The PAUT operator shall ensure that ultrasonic examination data is recorded in unprocessed form. A full and complete data recording set with no exclusionary gating, filtering other than receiver band-pass, or thresholding for responses from the calibration shall be included in the data record.
11.11
As a minimum, the gate(s) shall be set to cover at least ½ of B0 (ID) to at least T1 (OD) plus ½ thickness to ensure the full weld volume is covered by the gate.
11.12
The OmniScan readings should be set to display; List – 1 A%, DA, PA, SA and List 2 - U(m-r), S (m-r) S (r), S (m). If an equal PAUT system is used and qualified, similar measurement readings shall be used.
11.13
Scans parallel to weld shall be conducted manually to detect transverse flaws
11
with a conventional UT set up or Manual Phased Array Probe. These scans shall be at 15 degrees off parallel to the weld when weld reinforcement is still in place. 12.0
Data Analysis 12.1
The Phased Array System shall have software in which to display as a minimum an A, B, C, and S Scan images. See Figure 4 below.
Figure 4 12.2 13.0
A post analysis data evaluation software package may be used to analyze the Phased Array data, for example Tomoview, OmniPC, or equal.
Acceptance Criteria 13.1
All weld discontinuities shall be evaluated, using the refracted angle or VPA yielding the highest response, based on the indication level and length in accordance with the requirements herein the acceptance-rejection criteria of Table 1.
13.2
Any ultrasonic indication determined to be a Crack, Lack of Fusion (LOF), or Lack of Penetration (LOP) shall be rejected regardless of amplitude or length.
TABLE 1 ACCEPTANCEREJECTION CRITERIA Discontinuity Severity Class
% of FSH
Class A – any indication in this category shall be rejected (regardless of length).
> than 89% FSH
Class B - any indication in this category having a length greater than ¾ inch shall be rejected.
= or > than 50% FSH (SSL)
Class C -any indication in this category having a length greater than 2 in.
= or > than 25% FSH
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(ARL)
Equal to DRL to SSL
Class D (minor discontinuities) - any indication in this category shall be accepted regardless of length or location in the weld. 10.3
All recorded data shall be assessed to ensure full execution of the required scans of the Scan Plan over 100% of the required examination length.
10.4
Post-acquisition data analysis will result in numerous evaluative actions and manipulations intended to characterize flaw responses from benign geometries and metallurgical responses. Following is a general description of a process to serve as a basis for evaluation. This process, by its nature, will require modification to ensure complete and systematic disposition of the examination record.
10.5
The entire exam volume shall be analyzed, using gates and available cursors, to locate and identify the source, location and nature for all indications. Alternately, the examiner may choose manual plotting to augment on-board analysis, for example non-parallel or inconsistent geometries.
10.6
Ultrasonic signal or images resulting from weld root and weld crown geometries shall be investigated, and the basis for this classification shall be noted in the report form.
10.7
Any indication warranting evaluation shall be recorded so as to support the resultant disposition. The extent of recording should be sufficient for reviewers and subsequent examiners to repeat the result and should standalone as written record.
10.8
Rejectable indications shall be reported and include peak amplitude (A%), depth (DA) below the surface, Probe Offset (PA) Sound Path (SA), and the indications relative position for length S (m-r), Start S (r), Stop S (m) to provide location and depth information for repair. Cursor placement, measurement features and annotations and comments must clearly support disposition.
10.9
Transverse discontinuities detected by manual ultrasonic inspections (conventional or Phased Array) need not be recorded unless rejectable flaws are identified.
10.10
Flaw Length Measurements 10.10.1
Flaw indications may be measured for length by defining the continuous flaw response signals using the B and C scan views. Both views are needed to ensure the entire related length is considered. An indication shall be considered continuous even if data drops intermittently below evaluation level.
10.10.2
Saturated flaw signals may require rescanning at lower gain levels if the disposition of the indication cannot be assessed using the required elevated gain settings. When using Phased Array, scanning may be conducted at two different gain settings using a grouping feature which allows for two scans to be conducted at the same time using two different gain settings. One gain setting is Primary Reference Level (PRL) and the other is scanning gain at plus 6dB.
13
Less than 25% FSH (DRL)
10.10.3
11.0
12.0
As an alternative, flaw length measurement may be determined by 6 dB drop methods.
Data Recording and Documentation 11.1
All digital Phased Array data and Scan Plans shall become an archival record for a period of 10 years after the completion of the Project. The PA inspection company shall maintain all digital records, including PA Data, Scan Plans, Data reports and records.
11.2
Any merged Phased Array Data shall be saved and archived as a Merge set of data for analysis.
11.3
Any review and evaluation of the phased array data shall not change or affect the original phased array raw A-scan data.
11.4
An examination report shall be generated by the examiner at the time of evaluation. Examination reports may be output from the on-board reporting feature of the phased array unit provided all necessary information is included. Reports may also be produced in the written manual UT convention form.
Data Management System 12.1
Establish a data management system consistent with Project requirements.
12.2
A systematic file naming system shall be used to control data management of calibration and set-up files, phased array data files, and digitally generated data report forms.
12.3
All phased array data shall be saved as the original raw A-scan form.
12.4
Acceptable Welds. The report form for welds that are acceptable need only contain sufficient information to identify the weld, the operator including signature, and the acceptability of the weld. Completed inspection reports shall be forwarded to the Engineer.
12.5
Unacceptable Welds. Discontinuities that do not meet the acceptance criteria of paragraph 13, and require repair by excavation, shall be indicated on the weld by marking directly over the discontinuity for its entire length. The depth and indication level shall be marked on the nearby adjacent base metal.
12.6
Prior Inspection Reports. Before a weld subject to UT is accepted, all report forms pertaining to the weld, including any that show unacceptable quality before repair, shall be submitted to the Engineer.
12.7
Disposition of Reports. A full set of completed report forms of welds subject to UT shall be delivered to the Engineer upon completion of the work. Obligation to retain UT reports shall cease upon delivery of this full set to the Engineer or two full years after filing of the Notice of Completion, provided the Engineer is given advance written notice.
12.8
Scan Plan Reporting – The Scan Plan that was developed shall become a part of the final examination report as it contains much of the information required to be
14
documented.
Attachment A
15
Non Essential
Element pitch and gap dimension Focus (identify plane, depth, or sound path as applicable) Virtual aperture use, that is, number of elements and element width Element numbers used for focal laws Angular range of S‐Scan Documentation on permitted wedge angular range from manufacturer Documented calibration, TCG, and Angle Gain Compensation Scan pattern to ensure coverage Weld configurations to be examined, including thickness dimensions and base material product form (pipe, plate) The surfaces from which the examination shall be performed Technique(s) (straight beam, angle beam, contact, and/or immersion) Angle(s) and mode(s) of wave propagation in the material Search unit type(s), frequency(ies), and element size(s)/shape(s) Special phased array probes curved /shaped wedges, shoes, or saddles, when used. Phased Array Units (s) Calibration ‐ calibration block(s) and technique(s) Directions and extent of scanning Scanning (manual vs. automatic) Method for discriminating geometric from flaw indications Method for sizing indications Computer enhanced data acquisition, when used Scan overlap (decrease only) Personnel performance requirements, when required Personnel qualification requirements Surface condition (Examination surface, calibration block) Couplant: brand name or type Automatic alarm and/or recording equipment, when applicable Records, including minimum calibration data to be recorded (for example instrument settings) Method for determining delay laws if other than on‐board equipment algorithms included in the software revision specified Revision of software used in qualification Scanning device make and model Decrease in sampling rate during scanning for linear scans Flaw discriminating / characterizing method ‐ location and type Type, size and range as applicable, of interfering signal sources e.g.; roots and weld crown conditions, tapers, counterbores
Essential
Summary Table of Procedures Variables for PAUT Examinations
X X X X X X X X
X
X X X X
X
X X X X X X X X X
X X X X
X
X
X X
X X
X
Attachment B Performance Demonstration Program ™ (PDQ) Examinations Personnel shall demonstrate proficiency by satisfactory performance in a qualification exam. The qualification exam shall include the ability of the Phased Array UT (PAUT) personnel to correctly calibrate the PAUT equipment and complete the report associated with the examination as well as evaluate the specimen and discover discontinuities. The test specimens shall be representative of the details of typical welded joints and conditions, which will be encountered in the pipe construction. The PDQ Test Samples will be supplied by the Engineer and administered as follows: 1.0
2.0
The Phased Array Ultrasonic Examination Procedure shall be qualified in accordance with AWS D1.1 Section 6, paragraph 6.36 and 6.37 1.1
The PA procedure shall be qualified to detect acceptable and rejectable flaws in accordance with a Procedure Qualification (PQ) Test Protocol.
1.2
The PA procedure shall be qualified to dimension the length of flaws in accordance with a PQ Test Protocol.
Each certified PAUT Level II or Level III, qualified in accordance with ASNT, shall demonstrate their proficiency in the calibration and setup, data acquisition, and data analysis conduct of an Examiner Qualification Examination, (EQ). 2.1
The Examiner Qualification (EQ) shall be administered by a PAUT Level III designated by the Engineer, and in accordance with a Test Protocol.
2.2
A minimum of 4 Test Plates shall be administered with an approximate weld length of 24 inches per test plate
2.3
The test samples shall be a backing bar weld joint configuration
2.4
Each Test Set shall have flawed and unflawed grading units established.
2.5
The Test Set flaws shall be representative of the typical welding fabrication flaws conducive to the welding process to be used during the field examinations.
2.6
Grading shall be as follows: 2.6.1 2.6.2 2.6.3 2.6.4
Minimum 80% detection Minimum of 80 % flaw characterization Minimum of 80% accuracy No more than 20 % overcalls
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Examples of Scan Plans
Scan Plan at Skew 90‐1 and 270‐1
Figure 5
Scan Plan at Skew 90‐2 and 270‐2
Figure 6
17
