ULTRASONIC TESTING PROCEDURE · ULTRASONIC EXAMINATION OF WELDINGS PLUS-UT-02 A2 NON DESTRUCTIVE...

Document No Rev. ULTRASONIC EXAMINATION OF

WELDINGS

PLUS-UT-02 A2

NON DESTRUCTIVE TEST PLUS di 21 Confidential, Property of NDT PLUS

NDT PLUS Viale Lombardia, 60

20056 Trezzo sull’Adda (MI)

ULTRASONIC TESTING PROCEDURE

Issued by: Stefano Tarantola Approved by: Giuseppe Rivaroli

By signature and date on the front sheet of this Procedure by the relevant persons, the signature

on each page of this Procedure are waived

REVISIONS

Rev. Date Description

A1 2016/04/01 First issue

A2 2017/04/24 REVISIED ACCORDING TO ITN 07039 REV. 12


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INDEX

1. SCOPE AND APPLICABILITY ........................................................................................................... 4

2. REFERENCE DOCUMENTS ............................................................................................................... 4

3. EQUIPMENT ...................................................................................................................................... 4

6. CALIBRATION ................................................................................................................................... 7

7. EXAMINATION ................................................................................................................................. 9

8. EVALUATION .................................................................................................................................. 10

9. RECORDING LEVEL ........................................................................................................................ 10

10. ACCEPTANCE STANDARD ........................................................................................................... 11

11. PERSONNEL .................................................................................................................................. 11

APPENDIX “A” – Scanning technique - ................................................................................................... 14

APPENDIX “B” – Procedure for the equipment calibration - ................................................................. 15

APPENDIX “C” – Transfer correction - .................................................................................................... 17

APPENDIX “D” – Probes check – ............................................................................................................ 18

APPENDIX “E” – Test report – ................................................................................................................ 20


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1. SCOPE AND APPLICABILITY

1.1. This procedure describes the method to be followed for manual ultrasonic testing of the following :

• Butt welds

• Nozzle to shell and nozzle to ends welds

1.2. This procedure is applicable to the welds of pressure vessels, piping and other welds with any dimension in carbon and low alloy steels with thickness not less than 8 mm.

2. REFERENCE DOCUMENTS

2.1. ASME Section V– Edition 2015 : Article 4

2.2. ASME Sect. VIII Division 1 - Edition 2015 : Appendix 12

2.3. ASNT doc. SNT-TC-1A

2.4. ISO 9712

2.5. ITN 07049 REV.11

2.6. ITN 07039 REV.12

3. EQUIPMENT

3.1. Instrument Requirements

3.1.1. A pulse-echo digital ultrasonic instrument shall be used. The instrument shall be capable of operation at frequencies over the range of at least 1 MHz to 5 MHz and shall be equipped with a stepped gain control in units of 2.0 dB or less. If the instrument has a damping control, it may be used if it does not reduce the sensitivity of the examination. The reject control shall be in the “off” position for all examinations, unless it can be demonstrated that it does not affect the linearity of the examination. The instrument, when required because of the technique being used, shall have both send and receive jacks for operation of dual search units or a single search unit with send and receive transducers.

3.1.2. The ultrasonic instrument shall provide linear vertical presentation within ± 5% of the full screen height for 20% to 100% of the screen height. The procedure for evaluating screen height linearity is given by Appendix B.

3.1.3. Amplitude control shall be accurate over its useful range to ±20% of the nominal amplitude ratio. The procedure for evaluating amplitude control linearity is given in Appendix B procedure.

3.1.4. Screen Height Linearity and Amplitude Control Linearity shall be performed every three months for analog type instruments and one year for digital type instruments, or prior to first use hereafter.

3.2. Search Units

3.2.1. General. The nominal frequency shall be from 1 MHz to 5 MHz unless variables, such as production material grain structure, require the use of other frequencies to assure adequate penetration or better resolution. Search units with contoured contact wedges may be used to aid ultrasonic coupling.

3.2.2. The probes to be used, generally, for the examination of welds are the following :

Beam angle Transverse Wave

Frequency (MHz)

Probe size (mm)

45° – 60° - 70° 2 ÷ 4 20 x 22, 14x14, 8x9 0° 2 ÷ 4 Ø10 , Ø20

The smaller probes are used if the curvature of the material is small.


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3.2.3. The base metal adjacent to the joint shall be inspected by longitudinal wave probe in order to detect discontinuities that may have an important influence on the results of welded joint inspection.( see figure 3÷5)

Examination sensitivity shall be determined bringing first back wall echo at 80% FSH.

During inspection the operator shall allow for above discontinuities in order to take measures to avoid disturbances or, if necessary, to limit inspection to those areas which can be efficiently scanned.

3.2.4. In general, it shall be checked the 100% of welding volume. Figures 3 ÷ 5 diagram, shows in general, scanning path to follow for some of the most common geometrical conditions. In any case the scan plan shall is an essential variable of ultrasonic testing and it shall be specified before the inspection on a technique sheet issued and validated

3.2.5. When transverse wave angle beam probes are used, the following checks must be carried out :

✓ Check of the emission point of the ultrasonic beam, see appendix D;

✓ Check of the refraction angle. If a deviation of more than 2° is found, the probe must be corrected or changed, see appendix D.

3.3. Couplant

3.3.1. General - The couplant, including additives, shall not be detrimental to the material being examined.

3.3.2. Control of Contaminants (a) Couplants used on nickel base alloys shall not contain more than 250 ppm of sulfur. (b) Couplants used on austenitic stainless steel or titanium shall not contain more than 250 ppm of halides (chlorides plus fluorides).

3.3.3. For coupling purpose, the NDT FYP gel which satisfies the requirements of 3.3.2 shall be used.

3.3.4. The same coupling medium shall be used for both calibration and examination.

3.4. Calibration Blocks

3.4.1. General 3.4.1.1. Reflectors - Specified reflectors (i.e., side drilled holes, flat bottom holes, notches, etc.)

shall be used to establish primary reference responses of the equipment. 3.4.1.2. Material - The material from which the block is fabricated shall be of the same product form,

and material specification or equivalent P-Number grouping as one of the materials being examined. For the purposes of this paragraph, P-Nos. 1, 3, 4, 5A through 5C and 15A through 15F materials are considered equivalent.

3.4.1.3. Quality - Prior to fabrication, the block material shall be completely examined with a straight beam search unit. Areas that contain an indication exceeding the remaining back-wall reflection shall be excluded from the beam paths required to reach the various calibration reflectors.

3.4.1.4. Heat Treatment - The calibration block shall receive at least the minimum tempering treatment required by the material specification for the type and grade. If the calibration block contains welds other than cladding, and the component weld at the time of the examination has been heat treated, the block shall receive the same heat treatment.

3.4.1.5. Surface Finish The finish on the scanning surfaces of the block shall be representative of the scanning surface finishes on the component to be examined.

3.4.1.6. Block Curvature 3.4.1.6.1. Materials With Diameters Greater Than 20 in. (500 mm) For examinations in materials

where the examination surface diameter is greater than 20 in. (500 mm), a block of essentially the same curvature, or alternatively, a flat basic calibration block, may be used.

3.4.1.6.2. Materials With Diameters 20 in. (500 mm) and Less - For examinations in materials


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where the examination surface diameter is equal to or less than 20 in. (500 mm), a curved block shall be used. Except where otherwise stated in this Article, a single curved basic calibration block may be used for examinations in the range of curvature from 0.9 to 1.5 times the basic calibration block diameter. For example, an 8 in (200 mm) diameter block may be used to calibrate for examinations on surfaces in the range of curvature from 7.2 in. to 12 in. (180 mm to 300 mm) in diameter. The curvature range from 0.94 in. to 20 in. (24 mm to 500 mm) in diameter requires 6 curved blocks for any thickness range.

3.4.1.6.3. Alternative for Convex Surface - As an alternative to the requirements in 3.4.1.6.1 when examining from the convex surface by the straight beam contact technique, Appendix G of Art. 4 may be used.

3.4.2. Non-Piping Calibration Blocks 3.4.2.1. Basic Calibration Block - The basic calibration block configuration and reflectors shall be as

shown in Fig. 1. The block size and reflector locations shall be adequate to perform calibrations for the beam angles used.

3.4.2.2. Block Thickness - When two or more base material thicknesses are involved, the calibration block thickness shall be determined by the average thickness of the weld. Alternatively, a calibration block having the greater base material thickness may be used provided the reference reflector size is based upon the average or smaller weld thickness.

3.4.2.3. Block Range of Use - When the block thickness ± 1 in. (25 mm) spans two weld thickness ranges as shown in Fig. 1, the block’s use shall be acceptable in those portions of each thickness range covered by 1 in. (25 mm) of the calibration block’s thickness. As an example, a calibration block with a thickness of 1 ½ in. (38 mm) could be used for weld thicknesses of 0.5 in. (13 mm) to 2.5 in. (64 mm).

3.4.2.4. Alternate Block - Alternatively, the block may be constructed as shown in Nonmandatory Appendix J of ASME Sect. V Art. 4, Fig. J-431.

3.4.3. Piping Calibration Blocks - The basic calibration block configuration and reflectors shall be as shown in Fig. T-434.3. The basic calibration block shall be a section of pipe of the same nominal size and schedule. The block size and reflector locations shall be adequate to perform calibration for the beam angles used.

4. MISCELLANEOUS REQUIREMENTS 4.1. Identification of Weld Examination Areas

4.1.1. Weld Locations. Weld locations and their identification shall be recorded on a weld map or in an identification plan.

4.1.2. Marking. If welds are to be permanently marked, low stress stamps and/or vibratooling may be used. Markings applied after final stress relief of the component shall not be any deeper than1.2mm.

4.1.3. Reference System. Each weld shall be located and identified by a system of reference points. The system shall permit identification of each weld center line and designation of regular intervals along the length of the weld. A general system for layout of vessel welds is described in ASME Sect. V Art. 4 Nonmandatory Appendix A; however, a different system may be utilized provided it meets the above requirements.

5. TECHNIQUES (T-450) The techniques described in this Article are intended for applications where either single or dual element search units are used to produce: (a) normal incident longitudinal wave beams for what are generally termed straight beam examinations or

(b) angle beam longitudinal waves, where both refracted longitudinal and shear waves are present in the material under examination. When used for thickness measurement or clad examination, these examinations are generally considered to be straight beam examinations. When used for weld


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examinations, they are generally termed angle beam examinations or (c) angle beam shear waves, where incident angles in wedges produce only refracted shear waves in the material under examination are generally termed angle beam examinations Contact or immersion techniques may be used. Base materials and/or welds with metallurgical structures producing variable attenuations may require that longitudinal angle beams are used instead of shear waves. Additionally, co mputerized imaging techniques may enhance the detectability and evaluation of indications. Other techniques or technology which can be demonstrated to produce equivalent or better examination sensitivity and detectability using search units with more than two transducer elements may be used. The demonstration shall be in accordance with ASME Sect. V Article 1, T-150(a).

5.1. Coarse Grain Materials Ultrasonic examinations of high alloy steels and high nickel alloy weld deposits and dissimilar metal welds between carbon steels and high alloy steels and high nickel alloys are usually more difficult than ferritic weld examinations. Difficulties with ultrasonic examinations can be caused by an inherent coarse-grained and/or a directionally-oriented structure, which can cause marked variations in attenuation, reflection, and refraction at grain boundaries and velocity changes within the grains. It usually is necessary to modify and/or supplement the provisions of this Article in accordance with ASME Sect. V Article 1, T-150(a) when examining such welds in these materials. Additional items, which may be necessary, are weld mockups with reference reflectors in the weld deposit and single or dual element angle beam longitudinal wave transducers.

6. CALIBRATION

6.1. Instrument Linearity Checks - The requirements of Appendix C shall be met at intervals not to exceed three months or prior to first use thereafter.

6.2. General Calibration Requirements 6.2.1. Ultrasonic System - Calibrations shall include the complete ultrasonic system and shall be per-

formed prior to use of the system in the thickness range under examination. 6.2.2. Calibration Surface - Calibrations shall be performed from the surface (clad or unclad; convex or

concave) corresponding to the surface of the component from which the examination will be performed.

6.2.3. Couplant - The same couplant to be used during the examination shall be used for calibration. 6.2.4. Contact Wedges - The same contact wedges to be used during the examination shall be used for

calibration. 6.2.5. Instrument Controls - Any control which affects instrument linearity (e.g., filters, reject, or

clipping) shall be in the same position for calibration, calibration checks, instrument linearity checks, and examination.

6.2.6. Temperature - For contact examination, the temperature differential between the calibration block and examination surfaces shall be within 14°C. For immersion examination, the couplant temperature for calibration shall be within 14°C of the couplant temperature for examination.

6.3. Calibration for Non-Piping 6.3.1. System Calibration for Distance Amplitude Techniques

6.3.1.1. Calibration Block(s) - Calibrations shall be performed utilizing the calibration block shown in Fig. 1. Notches are optional.

6.3.1.2. Techniques - Nonmandatory Appendices B and C provide general techniques for both angle beam shear wave and straight beam calibrations. Other techniques may be used. The angle beam shall be directed toward the calibration reflector that yields the maximum response in the area of interest. The gain control shall be set so that this response is 80% ± 5% of full screen height. This shall be the primary reference level. The search unit shall then be manipulated, without changing instrument settings, to obtain the maximum responses from the other calibration reflectors at their beam paths to generate the distance-amplitude correction (DAC) curve. These calibrations


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shall establish both the distance range calibration and the distance amplitude correction.

6.3.1.3. Angle Beam Calibration. As applicable, the calibration shall provide the following measurements (Nonmandatory Appendix B contains general techniques): (a) distance range calibration; (b) distance-amplitude; (c) echo amplitude measurement from the surface notch in the basic calibration block. When

an electronic distance-amplitude correction device is used, the primary reference responses from the basic calibration block shall be equalized over the distance range to be employed in the examination. The response equalization line shall be at a screen height of 40% to 80% of full screen height.

6.3.1.4. Straight Beam Calibration - The calibration shall provide the following measurements (Nonmandatory Appendix C gives a general technique):

6.3.1.4.1. distance range calibration, and; 6.3.1.4.2. distance-amplitude correction in the area of interest. When an electronic distance-

amplitude correction device is used, the primary reference responses from the basic calibration block shall be equalized over the distance range to be employed in the examination. The response equalization line shall be at a screen height of 40% to 80% of full screen height.

6.4. Calibration for Piping 6.4.1. System Calibration for Distance Amplitude Techniques

6.4.1.1. Calibration Block(s) - Calibrations shall be performed utilizing the calibration block shown in Fig. 2

6.4.1.2. Angle Beam Calibration - The angle beam shall be directed toward the calibration reflector that yields the maximum response. The gain control shall be set so that this response is 80% ±5% of full screen height. This shall be the primary reference level. The search unit shall then be manipulated, without changing instrument settings, to obtain the maximum responses from the calibration reflectors at the distance increments necessary to generate a three-point distance-amplitude correction (DAC) curve. Separate calibrations shall be established for both the axial and circumferential notches. These calibrations shall establish both the distance range calibration and the distance amplitude correction.

6.4.1.3. Straight Beam Calibration - When required, straight beam calibrations shall be performed to the requirements of Nonmandatory Appendix C using the side drilled hole alternate calibration reflectors of 3.4.1.1. This calibration shall establish both the distance range calibration and the distance amplitude correction.

6.5. Calibration Confirmation 6.5.1. System Changes - When any part of the examination system is changed, a calibration check shall

be made on the basic calibration block to verify that distance range points and sensitivity setting(s) satisfy the requirements of 6.6.3.

6.5.2. Periodic Examination Checks - A calibration check on at least one of the basic reflectors in the basic calibration block or a check using a simulator shall be made at the finish of each examination or series of similar examinations, every 4 hr during the examination, and when examination personnel (except for automated equipment) are changed. The distance range points and sensitivity setting(s) recorded shall satisfy the requirements 6.6.3.

6.5.2.1. Simulator Checks - Any simulator checks that are used shall be correlated with the original calibration on the basic calibration block during the original calibration. The simulator checks may use different types of calibration reflectors or blocks (such as IIW) and/or electronic simulation. However, the simulation used shall be identifiable on the calibration sheet(s). The simulator check shall be made on the entire examination system. The entire system does not have to be checked in one operation; however, for its check, the search unit shall be connected to the ultrasonic instrument and checked against a calibration reflector. Accuracy of the simulator checks shall be confirmed, using the basic calibration block, at the conclusion of each


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period of extended use, or every three months, whichever is less. 6.5.3. Confirmation Acceptance Values

6.5.3.1. Distance Range Points - If any distance range point has moved on the sweep line by more than 10% of the distance reading or 5% of full sweep, whichever is greater, correct the distance range calibration and note the correction in the examination record. All recorded indications since the last valid calibration or calibration check shall be reexamined and their values shall be changed on the data sheets or re-recorded.

6.5.3.2. Sensitivity Settings - If any sensitivity setting has changed by more than 20% or 2 dB of its amplitude, correct the sensitivity calibration and note the correction in the examination record. If the sensitivity setting has decreased, all data sheets since the last valid calibration check shall be marked void and the area covered by the voided data shall be reexamined. If the sensitivity setting has increased, all recorded indications since the last valid calibration or calibration check shall be reexamined and their values shall be changed on the data sheets or re-recorded.

7. EXAMINATION

7.1. General Examination Requirements 7.1.1. Examination Coverage - The volume to be scanned shall be examined by moving the search unit

over the scanning surface so as to scan the entire examination volume for each required search unit.

7.1.1.1. Each pass of the search unit shall overlap a minimum of 10% of the transducer(piezoelectric element) dimension parallel to the direction of scan indexing.

7.1.1.2. Oscillation of the search unit is permitted if it can be demonstrated that overlapping coverage is provided.

7.1.2. Pulse Repetition Rate - The pulse repetition rate shall be small enough to assure that a signal from a reflector located at the maximum distance in the examination volume will arrive back at the search unit before the next pulse is placed on the transducer.

7.1.3. Rate of Search Unit Movement - The rate of search unit movement (scanning speed) shall not exceed 6 in./s (150 mm/s), unless:

7.1.3.1. the ultrasonic instrument pulse repetition rate is sufficient to pulse the search unit at least six times within the time necessary to move one-half the transducer (piezoelectric element) dimension parallel to the direction of the scan at maximum scanning speed; or,

7.1.3.2. a dynamic calibration is performed on multiple reflectors, which are within ±2 dB of a static calibration and the pulse repetition rate meets the requirements of

7.1.4. Scanning Sensitivity Level 7.1.4.1. Distance Amplitude Techniques The scanning sensitivity level shall be set a minimum3 of 6 dB

higher than the reference level gain setting. 7.1.4.2. Non-Distance Amplitude Techniques - The level of gain used for scanning shall be appropriate

for the configuration being examined and shall be capable of detecting the calibration reflectors at the maximum scanning speed.

7.1.5. Surface Preparation - When the base material or weld surface interferes with the examination, the base material or weld shall be prepared as needed to permit the examination.

7.2. Weld Joint Distance Amplitude Technique - When the referencing Code Section specifies a distance amplitude technique, weld joints shall be scanned with an angle beam search unit in both parallel and transverse directions (4 scans) to the weld axis. Before performing the angle beam examinations, a straight beam examination shall be performed on the volume of base material through which the angle beams will travel to locate any reflectors that can limit the ability of the angle beam to examine the weld volume.

7.2.1. Angle Beam Technique 7.2.1.1. Beam Angle - The search unit and beam angle selected shall be 45 deg or an angle appropriate

for the configuration being examined and shall be capable of detecting the calibration reflectors, over the required angle beam path.

7.2.1.2. Reflectors Parallel to the Weld Seam - The angle beam shall be directed at approximate right


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angles to the weld axis from both sides of the weld (i.e., from two directions) on the same surface when possible. The search unit shall be manipulated so that the ultrasonic energy passes through the required volume of weld and adjacent base material.

7.2.1.3. Reflectors Transverse to the Weld Seam - The angle beam shall be directed essentially parallel to the weld axis. The search unit shall be manipulated so that the ultrasonic energy passes through the required volume of weld and adjacent base material. The search unit shall be rotated 180 deg and the examination repeated. If the weld cap is not machined or ground flat, the examination shall be performed from the base metal on both sides of the weld cap in both weld axis directions.

7.2.2. Restricted Access Welds - Welds that cannot be fully examined from two directions using the angle beam technique (e.g., corner and tee joints) shall also be examined, if possible, with a straight beam technique. These areas of restricted access shall be noted in the examination report.

7.2.3. Inaccessible Welds (- Welds that cannot be examined from at least one side (edge) using the angle beam technique shall be noted in the examination report. For flange welds, the weld may be examined with a straight beam or low angle longitudinal waves from the flange face provided the examination volume can be covered.

8. EVALUATION

8.1. General - It is recognized that not all ultrasonic reflectors indicate flaws, since certain metallurgical discontinuities and geometric conditions may produce indications that are not relevant. Included in this cat e- gory are plate segregates in the heat-affected zone that become reflective after fabrication. Under straight beam examination, these may appear as spot or line indications. Under angle beam examination, indications that are determined to originate from surface conditions (such as weld root geometry) or variations in metallurgical structure in austenitic materials (such as the automatic-to-manual weld clad interface) may be classified as geometric indications. The identity, maximum amplitude, location, and extent of reflector causing a geometric indication shall be recorded. The following steps shall be taken to classify an indication as geometric:

8.1.1. Interpret the area containing the reflector in accordance with the applicable examination procedure. 8.1.2. Plot and verify the reflector coordinates. Prepare a cross-sectional sketch showing the reflector

position and surface discontinuities such as root and counterbore. 8.1.3. Review fabrication or weld preparation drawings. Other ultrasonic techniques or nondestructive examination methods may be helpful in determining a reflector’s true position, size, and orientation.

8.2. Evaluation Level 8.2.1. Distance Amplitude Techniques - All indications greater than 20% of the reference level shall be

investigated to the extent that they can be evaluated in terms of the acceptance criteria of the referencing Code Section.

8.2.1.1. The length of the indications shall be determined by the 50% DAC method. 8.2.2. Non-Distance Amplitude Techniques - All indications longer than 40% of the rejectable flaw size

shall be investigated to the extent that they can be evaluated in terms of the acceptance criteria of the referencing Code Section.

8.3. Evaluation of Laminar Reflectors - Reflectors evaluated as laminar reflectors in base material which interfere with the scanning of examination volumes shall require the angle beam examination technique to be modified such that the maximum feasible volume is examined, and shall be noted in the record of the examination (10.3).

8.4. Alternative Evaluations - Reflector dimensions exceeding the referencing Code Section requirements may be evaluated to any alternative standards provided by the referencing Code Section.

9. RECORDING LEVEL

Imperfections which produce a response greater than 20% of the reference level shall be investigated to the extent that the operator can determine the shape, identity, and location of all such imperfections and evaluate them


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in terms of the acceptance standards.

10. ACCEPTANCE STANDARD

Discontinuities interpreted as crack, lack of fusion or incomplete penetration are unacceptable, regardless of their size. Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths which exceed: - 6 mm for welds with thickness ≤19 mm; - 1/3 t, when the wall thickness t is > 19 and ≤ 57 mm; - 19 mm. for welds with thickness > 57 mm; If edges of different thickness are joined in the weld, the thickness to be considered is the lesser of the thickness under examination. All discontinuities considered unacceptable shall be removed from the weld, and the weld shall be repaired by the appropriate procedures; the repaired areas of the weld and their adjacent areas shall be re-examined by ultrasonic test as described in this procedure.

11. PERSONNEL

Personnel performing ultrasonic examination and evaluating the results shall be qualified to at least the level II in

accordance with the recommendations of ASNT Doc. SNT -TC-1A o ISO 9712.

12. DOCUMENTATION 12.1. Recording Indications

12.1.1. Non-Rejectable Indications - Non-rejectable indications shall be recorded as specified by the referencing Code Section.

12.1.2. Rejectable Indications - Rejectable indications shall be recorded. As a minimum, the type of indication (i.e., crack, non-fusion, slag, etc.), location, and extent (i.e., length) shall be recorded.

12.2. Examination report - For each ultrasonic examination, the following information shall be recorded: 12.2.1 Manufacturer; 12.2.2. Procedure identification and revision; 12.2.3. Job order, drawing, denomination, serial numbers of unit examined; 12.2.4. Customer, inspection authority; 12.2.5. Extension of examination and/or stage of intervention 12.2.6. Operating conditions such as:

- present conditions of surfaces examined; - coupling means; - instrument identification (including manufacturer’s serial number); -probe identification (including manufacturer’s serial number, frequency, and size); -search unit cable(s) used, type and length; - calibration block; -instruments reference level gain;

12.2.7 Recording of indication as specified at point 9. 12.2.8. Results and date of examination; 12.2.9. Identification and signature of operator and/or level II technician in charge.


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Figure 1– Non Piping basic calibration block


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Figure 2– Piping basic calibration block


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APPENDIX “A” – Scanning technique -

Figure 3: scanning techniqe for butt weld.

Figure 4: scanning technique for nozzle welds.

Figure 5: scanning technique for nozzle welds.

* to be performed for

diameter > 300 mm only


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APPENDIX “B” – Procedure for the equipment calibration - HORIZONTAL LINEARITY Using direct beam, longitudinal-wave probe and a steel block as shown in the following figure 1: Material

Carbon or low alloys steel

Surface roughness < 3,2 micron (125 micro inches) Holes A, B, C diameter 3 ± 0,1 mm Tolerance on dimensions ± 0,1 mm Block thickness 25 mm

Position the probe on the 25mm thick area of the block, and use the commands on the device to adjust the time axis so that 11 (eleven) back wallas echo appear. For positioning and measuring the postion of the time axis, adjust the amplification so that each back wall echo is at 50% FSH (full screen heigth) during measurement. Adjust the initial front of the signals corresponding to the third and to the ninth back walls echi to 20% and 80% respectively of the time scale. Note the position of the other background returns and enter the results as specified in table 1. These readings should be approximated to 1% of the time axis. Reading values should be within the acceptance indicated in the table A VERTICAL LINEARITY Use a transverse-wave probe with beam inclined 45° or 60° and a steel block as diagrammed in fig. 1. Adjust the probe to a position such as to obtain the response from holes A and B (located at ½ and ¾ of the thickness) in 2:1 ratio with the highest echo adjusted at 80% FSH. Without moving the probe, adjust the amplification so as to bring the echo from hole A from 100% FSH to 10% FSH at steps of 10% FSH. Read the heigth of the response from hole B and record the values as specified in the table B. These readings should have an accuracy of 1% FSH. Readings values be within the acceptance limits indicated in the table B. DEVICE FOR REGULATING AMPLIFICATION Use a transverse-wave probe with beam inclined 45° or 60° and steel block as diagramed in fig. 1. Position the probe so as to evidence on the screen hole C located at ½ thichness and subsequently:


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Adjust the corresponding echo according to the instruction given in the table C. Adjust the amplification control to make changes specifiedin the table . Read the heigth of the resulting echo and record it with an accurancy of 1% FSH. Readings values should be withhin the acceptance limits indicated in the table.

Table A

Table B

Table C


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APPENDIX “C” – Transfer correction - TRANSFER CORRECTION GENERAL Unless the test sensivity is set on a test block which is acustically representative of the object, a transfer correction shall be determined, and applied if necessary as follow. STRAIGTH BEAM PROBE The probe is placed on the reference block and the gain setting required to bring the first and second backwall echo up to the same height on the screen are recorded (values V1 % V2 in figure A). The values are then plotted against sound path length and a line 2 draw through them. The probe is then positioned on the test object and the above procedure repeated (value V3 and V4 and line 1 in figure A), the transfer correction is given by difference between the two lines (see figure A). ANGLE BEAM PROBE The probes are positioned on the referece block, first in V formation, second in W formation, and the gain setting required to bring the echoes to the same heigth on the screen are recorded ( values V1 & V2 in figure A). The probe are then similary positioned on the test object, and the procedure repeated (value V3 & V4 and Line 1 in figure A)

Line 1 : curve of the test object

Line 2: curve of the refence block

- If transfer correction is less then 2 dB, no any correction is necessary.

- If the transfer correction is between 2 ÷ 12 dB the difference shall be added to refence level.

- If the transfer correction is over 12 dB a investigation is necessary for define understand the reason and technique can

be change and revision of procedure may be necessary.

SOUND PATH

GA

IN

TRANSFER

CORRECTION

Line 1

Line 2

V1

V2

V3

V4


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APPENDIX “D” – Probes check – The probe shall be inspected to check that they function correctly. As preliminary activity the exit point and the refracted angle shall be verified as follow. Using a reference block I.I.W. n.1. If a significant difference between theoretical and actual values (greater than 2 mm for exit point or greater than 1° for the refracted angle) is noted, the actual values shall be marked on the probe. Using the same ultrasonic apparatus, set at 80% FSH the signal from the reflectors placed on the calibration blocks normally used for the inspection (side drilled holes or flat -bottomed), positioned 70 to 100 mm and 150 to 200 mm from the scanning surface, and record the amplification. The results shall be compared with previous test results and the results of other probes with the same nominal frequency and size of crystal. Should the results differ by more than 6 dB, the probe is not to be considered acceptable.

EXIT POINT AND REFRACTED ANGLE VERIFICATION EXIT POINT:

• Position the search unit as shown of the picture • Move the search unit back and forth until the peak signal from the curve is obtained • Verify the correspondence between the notch and the exit point marked on the probe.


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PLUS-UT-02 A2




REFRACTED ANGLE

• Position the search unit on scale “A” or “B” • Move the search unit back and forth until the peak signal from the hole is obtained • Read the refracted angle from the position on scale “A” or “B” coinciding with the point -of-incidence.


WELDINGS

PLUS-UT-02 A2




APPENDIX “E” – Test report –


WELDINGS

PLUS-UT-02 A2




ULTRASONIC TESTING PROCEDURE · ULTRASONIC EXAMINATION OF WELDINGS PLUS-UT-02 A2 NON DESTRUCTIVE...

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Transcript of ULTRASONIC TESTING PROCEDURE · ULTRASONIC EXAMINATION OF WELDINGS PLUS-UT-02 A2 NON DESTRUCTIVE...