Ut Procedure Ons

OMKAR NDT SERVICES

ULTRASONIC TESTING PROCEDURE

1/1/2014 PROCEDURE No.: ONS/UT/01 Prepared & Approved By : Rajesh Ahire, ASNT NDT Level-III(UT,RT,MPT,PT)

OMKAR NDT SERVICES ULTRASONI RASONIC C TESTING ING PROC EDURE

PROCEDURE No.: ONS/UT/01 REVISION :00

DATE:01/01/2014

CONTENTS 1. Scope 2. Reference 3. Personnel 4. Equipment 5. Instru Instrume ment nt calibr calibrati ation on 6. Records 7. Exam Examin inat atio ion n techn techniq ique ue 8. Sear Search chin ing g uni units ts 9. Cast Castin ing g cond condit itio ions ns 10. Couplants Couplants 11. Calibration and reference reference block(Straight beam technique) 12. Straight Beam Examination 13. Angle Beam Examinati Examination on 14. Evaluation Evaluation 15. Acceptance Acceptance criteria criteria 16. Conditions of backup backup Radiography Radiography

PREPARED AND APPROVED BY

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PROCEDURE FOR ULTRASONIC EXAMINATION ON CARBON AND LOW ALLOY STEEL CASTINGS 1. SCOPE 1.1 This guideline defines the requirements of equipment calibration, examination procedure and acceptance criteria of heat-treated carbon and low alloy steel castings by straight and angle beam techniques. 1.2 The test is conducted using longitudinal waves and shear waves of high frequency by surface contact on the parent metal such that the entire volume of the material is exam by movement of the probes. 1.3 This method covers technique to be employed at normal temperature, care is to be taken to ensure that the temperature of test pieces is not above the temperature for which the probe is designed. 1.4 This procedure shall be demonstrated prior to qualification. 2. Refe Refere renc nce es ASME Section V Article 5 (2010), ASME SA609, ASME B16-34, ASNT SNT-TC-1A (2006), and Customer approved standard, 3. PERSONNEL All NDE personnel carrying ultrasonic testing shall be qualified to ASNT SNTC-1A Table 1A as a minimum ASNT Level I or equivalent. All NDE personnel carrying out ULTRASONIC Interpretation shall be qualified to ASNT Level II or equivalent. The personnel shall be qualified by ASNT LEVEL III person as per in company written practice. 4. EQUIPMENT 4.1 The equipment is of pulse echo reflection type having a scan presentation capable of generating, receiving amplifying and displaying high frequency pulses usually In the range of 1 MHZ TO 5 MHZ. 5. Instru Instrume ment nt Calibr Calibrati ation: on: 5.1 The electronic equipment shall provide linear vertical presentation with in +or- 5% of full screen height for at least 80% of screen height. 5.2 The equipment shall contain a calibrated attenuator, accurate accurate over occur its range + or – 10% or DB which will allow measurement of signals beyond the linear range of instrument. 5.3 The sweep range linearity shall be checked with IIW/ASTM/DIN testing blocks and the readings shall not deviate more than + or – one minor sub divisions of the equipment.


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5.4. As IIW/DIN/ASTM blocks are not acoustically equivalent to steel castings, the metal path distances may be calibrated with standard reference blocks as in the same material with bottom hole. 5.5 From quantitative analysis of indications, beam spread measurement in vertical as well as horizontal planes may be performed by suitable techniques using a calibration blocks with f lat bottom side drilled holes at various depths. 6. RECORD The following data shall be recorded while performing the Ultrasonic tests 1. Ultrasonic Ultrasonic frequenc frequency y 2. Reje Reject ct 3. Setting Setting range range 4. Sweep Sweep delay 5. DAC boundary boundary 6. Automatic alarm when when required 7. EXAMI EXAMINAT NATION ION TECHNIQU TECHNIQUES ES 7.1 The transmission of waves shall be done by direct contact pulse echo method. 7.2 Manual operation with visual or audio monitoring is to be done. 7.3 The rate of scanning shall not exceed 150mm/sec. The ferrite castings shall be normally tested by straight beam technique. Supplementary angle beam examination shall be performed in areas where a back back reflection cannot cannot be maintained during the straight beam examination shall be performed in areas where a back reflection cannot be maintained during the straight beam examination or where the angle between two surface of the castings is more than 15 degree if required. 8. SEARCHING SEARCHING UNITS UNITS 8.1 Nominal frequency shall be 2 MHZ or 4 MHZ for straight beam techniques. A frequency 1 MHZ may be used for sections over 50 mm in thickness. 8.2 Angle beam search unit unit shall be in the range of 40 to 75 degree degree inclusive measured measured to the perpendicular of the entry surface of the castings under test. The frequency is usually of 2 MHZ. 8.3 Longitudinal search units shall have a maximum active area of 625sq mm with a maximum dimension of 28.6 mm for angle beam scanning search units with a maximum active transducers. Length units may be used for evaluation e valuation and pin pointing indications.


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COMPRESSION WAVE: A Combined double compression wave probe will be used up to 50 mm wall thickness. Above 50 mm, a single compression probe shall be used in addition. SHEAR WAVE: Shear wave probes shall shall be applied when an effective effective examination of a critical critical area cannot be examined using longitudinal beam as a result of casting design or possible discontinuity orientation.

9. CASTINGS CASTINGS CONDITION CONDITIONS. S. 9.1. Casting shall be heat treated for mechanical properties before being ul trasonically inspected. Test surface of castings shall be free of (SCALE, DIRT, PAINT, OR MACHINING MARKS) any material that will interfere and impair the transmission of ultrasonic vibration. Test surface may be as cast, blasted, ground or machined. 9.2 The ultrasonic inspection shall be conducted prior to any machining that prevents inspection of these areas of the casting. 10. COUPLA COUPLANTS NTS: Oil, grease, liquid soap and cellulose paste are all suitable Couplants. The same Couplants shall be used for calibration and test. Couplants to be removed after use. 11. CALIBRATION AND AND REFERENCE BLOCK (Straight (Straight beam technique) technique) 11.1 References blocks containing flat-bottom holes as shown as per standard are used to establish test sensitivities. Hole diameter shall be 6.25mm for all metal distance and shall be flat with in + or -0.05mm. The hole shall be straight and perpendicular to the entry surface with in ‘0’ deg ‘30’ Min and located with 0.8 mm of longitudinal axis. Counter bore shall be 12.5mm Dia and 3.2mm deep, The ends of the reference block shall be flat and parallel with in 0.25 mm. The hole bottom shall be thoroughly cleaned, dried and immediately plugged to prevent corrosion. 11.2 The reference block f or which the same straight beam search unit guides the maximum signal amplitude for 6.25mm FBH is determined first. The max peak obtained is kept at 80% of screen height with attenuator controls without distributing the settings and controls of the unit, the search unit is kept over the other reference blocks and beamed towards the flat bottoms holes. The height of echo peaks is marked on the CRT screen. These points together with 80% reference mark are joined smooth smooth to form the amplitude reference line. This is the acceptance acceptance quality reference line, based on the above calibration procedure. PREPARED AND APPROVED BY

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11.3 Transfer correction shall be employed, as the casting surface will be normally rough than that the test block. This is achieved as follows, 11.4 The test block, which over all length most closely matches the casting thickness, is selected and search unit is positioned to obtain a back reflection of 80% of screen height. The region of the castings that has parallel walls and a surface condition representative of the rest of the castings are selected and a back wall reflection is obtained from this area with straight beam search unit. The attenuator controls are adjusted to bring it to 80% screen height. The difference in settings is added to the values obtained in accordance by adjusting the settings; The difference in settings is added to the values obtained in accordance by adjusting the settings. The testing is carried out i.e. + or 6 DB (OR) two times the reference level to permit small signal amplitudes to be more readily detected. Signal evaluation is done at reference at level settings. REFERENCE BLOCKS:


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OMKAR NDT SERVICES PROCEDURE No.: ONS/UT/01 REVISION :00

ULTRASONI RASONIC C TESTING ING PROC EDURE

DATE:01/01/2014 Page 7 of 10

TABLE: 1 TABLE OF SIZES HOLE DIAMETER

METAL DISTANCE A

HOLE DEPTH .B

Overall length C

DIAMETER D

¼”

½”

½”

1”

2”

¼”

1”

¾”

1 ¾”

2”

¼”

1 ½”

½”

2”

2”

¼”

2”

¾”

2 ¾”

2”

¼”

2 ½”

½”

3”

2”

¼”

3”

¾”

3 ¾”

2”

¼”

3 ½”

½”

4”

2 ½”

¼”

4”

½”

4 ½”

2 ½”

¼”

6”

¾”

6 ¾”

3”

¼”

10”

¾”

10 ¾”

4”

¼”

E

½”

E+1/2”

5”

12. STRAIGHT STRAIGHT BEAM EXAMINATI EXAMINATION ON 12.1 The ultrasonic beam is introduced perpendicular to the surface. The specified casting section is completely covered with 10% overlap between successive scanning. 12.2. During inspection areas of the areas of the casting having parallel wall areas showing complete loss of back echo are rechecked to determine the loss of back reflection is not evident, either angle beam examination or any other NDT may be used to establish the validity of rejection. 12.3 When continuous indication are observed equal to or greater than the amplitude reference line. 12.4 The boundary of area of indication are marked by moving the search unit away from the center of discontinuity until the echo height falls by 50 %( 6db). 12.5 In certain castings because of very long metal path distance or curvature of the test surface, the area over which a given discontinuity of the casting. In such cases consideration of the beam spread must be used for realistic evaluation of the discontinuity.


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13. ANGLE ANGLE BEAM EXAMINATI EXAMINATION ON Calibration and Reference Blocks 13.1 Reference blocks shall be made of a material material similar in metallurgical structure as the castings being examined including chemical composition and heat treatment. 13.2 The basic calibration blocks as per TABLE 2 13.3 Distance amplitude correction curves shall be established for covering the completed examination distance range. The first point on the curves shall be obtained by placing the search unit not less than 3/8-vee path to the calibration holes and positioning for maximum response. Similarly th the search unit is placed at 5/8 th, 7/8 nodal points, without changing on the CRT screen. These points are joined by smooth line to form the D.A.C curve. 13.4 Transfer method shall be used to correlate the responses from the basic calibration block and from the casting to compensate the difference in attenuation resulting from surface or material difference. PREPARED AND APPROVED BY

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13.5 For all indications, which equals or exceed the D.A.C curve the boundary of the area has to be established by moving the search unit from the center of discontinuity until the echo height falls by 50% (6 db drop method) 13.6 In certain castings because of very long metal path distance or curvature of the examination surfaces; the surface area over which a given discontinuity is detected may be considerably longer or small than the actual area of the discontinuity of the casting. In such cases, consideration of the beam spread must be used for realistic evaluation of the discontinuity. Dimensions of calibration calibration blocks for Angle Beam Examination: Examination: TABLE 2 NORMAL PRODUCTION CALIBRATION BLOCK HOLE DIAMETER (d) mm Material thickness mm Thickness (t) mm (+/-0.05) Up to 25 inch 25 2.4 Over 25 to 50 50 3.2 Over 50 to 100 100 4.8 Over 100 to 150 150 6.3 Over 150 to 200 200 7.9 Over 200 to 250 250 9.5 Over 250 As produced material See note 1 thickness NOTE: 1 For each increase in 50 mm, or a fraction there of the hole diameter shall increase increase in 1.6mm NOTE: 2 For block sizes over 75mm in thickness t , the distance from the hole to end of the block shall be ½”t min, to prevent coincident reflections from the hole and the corner. Blocks FABRICATED WITH A 50 MM minimum dimensions need not be modified if the corner and hole indications can be easily resolved. 14. EVALUATION EVALUATION.. Evaluation of defects shall be decided according to ANSI B 16.34 or customer approved standard when required. 15. Acceptance Acceptance criteria criteria 15.1 Straight Beam examination: Indications which are equal (or) exceed the DAC are unacceptable. unacceptable. Any reduction of back reflection of 75% or greater that has been determined to be caused by a discontinuity over an area of 10 cm sq with a minimum length of 55 mm is unacceptable. PREPARED AND APPROVED BY

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0

15.2 Angle beam examination: Indication which are equal to or exceed those obtained 60 V notch 25.4mm long and having a depth of 5% of the nominal wall thickness in a test piece are unacceptable. 16. Conditions of back up radiography radiography Discontinuities of borderline acceptability from ultrasonic examination shall be radiographed to determine their acceptability, if so required. Where casting orientation is such that a proven ultrasonic operator or someone of a comparable or higher authority in the manufacturing associate facility only. In the event of radiography being necessary, this shall be carried out in accordance with the procedure with acceptance standard as laid down in ANSI B16.34.


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