Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. इंटरनेट मानक “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “प0रा1 को छोड न’ 5 तरफ” Jawaharlal Nehru “Step Out From the Old to the New” “जान1 का अ+धकार, जी1 का अ+धकार” Mazdoor Kisan Shakti Sangathan “The Right to Information, The Right to Live” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 15531 (2004): Recommended Practice for Ultrasonic Testing of Weld Fillets of Non-Linear Joints [MTD 21: Non-Destructive Testing]
Transcript
Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.
इंटरनेट मानक
“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru
“Step Out From the Old to the New”
“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan
“The Right to Information, The Right to Live”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
“Invent a New India Using Knowledge”
है”ह”ह
IS 15531 (2004): Recommended Practice for UltrasonicTesting of Weld Fillets of Non-Linear Joints [MTD 21:Non-Destructive Testing]
IS 15531:2004
Indian Standard
RECOMMENDED PRACTICE FORULTRASONIC TESTING OF
WELD FILLETS OF NON-LINEAR JOINTS
ICS 77.040.20
0 BIS 2004
BUREAU OF IN DIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by theNon-Destructive Testing Sectional Committee had been approved by the Metallurgical Engineering DivisionCouncil.
This standard has been prepared to provide guidance to the testing personnel for testing and inspection of fusionwelded non-linear joints by di~ct contact pulse-echo method. ‘This standard gives detailed procedure ofexamination of weld fillets of non linear joints such as, set on, set through, structural T-joints, and cruciformjoints and node joints.
For the purpose of deciding whether a particular requirement of this standard is complied with, the final valueobserved or calculated, expressing the result of a test or analysis, shall be mun&d off in accomlance withIS 2:1960 ‘Rules for rounding off numerical value (revised)’. The number of significant places retained in therounded off value should be the same as that of the specified value in this standard.
IS 15531:2004
Indian Standard
RECOMMENDED PRACTICE FORULTRASONIC TESTING OF
WELD FILLETS OF NON-LINEAR JOINTS1 SCOPE
1.1 This standard prescribes the method for ultrasonictesting and inspection of fusion welded non-linearjoints by direct contact pulse-echo method. Thismethod is applicable to material thickness over 6 mm.
1.2 The category includes set-on, set-through,structural T-Joints, Cruciform joints and node joints.
1.3 The requirements are established to scan theentire volume of weld heat-affected zone, and bothfusion faces from at least one direction for detection,location and evaluation of discontinuities.
2 REFERENCES
The following standards contain provisions whichthrough reference in this text, constitute provision ofthis standard. At the time of publication, the editionsindicated were valid. All standards are subject torevision, and parties to agreements based on thisstandard are encouraged to investigate the possibilityof applying the most recent editions of the standardsindicated below:
1S No. Title
2417:2003 Glossary of terms relating toultrasonic testing (second revision)
4904:1990 Calibration blocks for use inultrasonic non-destructive testing(third revision)
13805:2004 General standard for qualificationand certification of non-destructivetesting personnel (/hi revision)
3 TERMINOLOGY
For the purpose of this standard the definitions givenin IS 2417 shall apply.
4 EQUIPMENT
4,1 The ultrasonic apparatus shall be capable ofproducing receiving and displaying high frequencyacoustic pulses over the nominal range of 1 MHz to 5MHz and shall be of pulse-echo reflection type.
4.2 The ultrasonic instrument shall provide linearvertical presentation within + 5 percent of full screenheight from 20 percent to 80 percent of the full screen
height. The screen height linearity shall be measuredand recorded in accordance with IS 4904.
4.3 The amplifier of the instrument shall have adynamic range of not less than 24 dB up to 80 percentof full screen height.
4.4 The ultrasonic apparatus shall have an amplitudecontrol in steps of not greater than 2 dB for at least 20dB and have an accuracy of* 2 dB over any 20 dBrange.
4.5 The linearity of the time base shall be as describedin IS 4904.
5 BASIC CALIBRATION BLOCK
5.1 To establish a primary response of the equipmentreference reflectors shall be used.
5.2 The reference reflectors shall be located in a flatbasic calibration block (see Fig. 1).
5.3 The material from which the calibration block iscalibrated shall be of the same material form (namelyplate, forging, tubes, etc) having similar acousticalcharacteristics and surface roughness as that of thematerial to be examined.
5.4 The temperature difference between theexamination and the calibration block surfaces shallbe within 15°C.
5.5 The thickness of the calibration block shall beequal to the maximum thickness of the member fromwhich scanning is to be c&ried, within f 10 percent ofthickness (T).
5.6 For evaluation of all discontinuities in the body ofthe weld three cylindrical holes of diameter 3 mmequally spaced perpendicular to the sound beam axisand parallel to the scanning surface of the calibrationblock shall be used as reference reflectors (see Fig. 1).
%7 Where it is not practicable to have more than onecylindrical hole the same shall be located at l/2T.
5.8 Two 25 mm x 1.5 mmx 1.5 mm square notchesshall be used for evaluating discontinuities at or nearthe surface (see Fig. 1).
1
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IS 15531:2004
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FIG.1 BASICCALIBRATIONBLOCK
6 PROBE
6.1 A shear wave probe which produces an angle of45° to 70° in the examination medium is normallyused. The selection of the beam angle is dependent onthe thickness and geometry of the weld. Therecommended beam angles for different thickness ofmaterial are shown below:
Thickness Beam Angle Inside the Medium
(1) (2)
Upto 30 mm 70°‘30 to 50 mm 60”Over 50mm 45°
Probes with a beam angle less than 45° and more than70° may be used, if the geometry of the weld is moreadaptable to the chosen beam angle. Shoes may befound necessary to fit into the probes to suit thecurvature of the surface. Whenever such probes areused for examination Calibration also has to be donewith the same type.
6.2 The nominal frequency shall be in the mnge of 2to 4 MHZ. Unless variables such as productionmaterial, grain structure require the use of otherfrequencies to assure adequate penetration or betterresolution.
7 COUPLANT
A satisfactory couplant, liquid or paste having goodwetting properties to permit the transmission of
mechanical vibrations between the probe and materialunder test shall be used. Oil, glycerine, water, greases,silicone and white lead paste are among the morecommonly used couplant.
8 SURFACE PREPARATIONS
8.1 The base metal on each side of the weld shall befree of weld spatter, surface irregularities or foreignmatter that might interfere with the examination.
8.2 The weld ripples or weld surface irregularitiesshall be removed by any suitable mechanical means tosuch a degree that the resulting ultrasonic examinationfrom any remaining irregularities cannot mask anyobjectionable defects.
8.3 The volume of the base material through whichthe sound will travel in angfe beam examination shallbe completely scanned with a straight beam searchunit, usually of 2 MHZ frequency to defect reflectionswhich might affect interpretation of angle beamresults. This is not intended as an acceptance/rejectionexamination.
8.4 Dual probes comprising a separate transmitter andreceiver acoustically separated from each other maybe employed in plates of thickness 5 to 12 mm forbetter defection of reflectors.
9 DISTANCE AMPLITUDE CORRECTION
9.1 Compensation for the distance transverse by theultrasonic beam as it passes through the material isprovided by the use of DAC curves.
2
9.2 The angle beam probe ‘shall be centrallypositioned on the calibration block surface anddirected towards the reference reflectors. The soundbeam shall be oriented perpendicular to the axis of theside drilled holes. The probe is positioned formaximum response from the side-drilled hole thatgives the highest amplitude. The sensitivity controlsare adjusted to provide 80 percent of full screenindication from the hole. The peak of the indication ismarked on the screen. The probes are positioned atother nodel positions covering their expected
examination range. The corresponding peaks aremarked on the CRT screen. The peaks are joined bya smooth line whose length cover the examinationrange to generate a DAC curve.
9.3 For evaluation of discontinuities orientedperpendicular to a examination surface at or near thesurfaces, the probe is positioned at appropriatedistance necessary for maximum signal amplitudefrom the square notch machined on the oppositesurface of the calibration block. This amplitudereference level is alone chosen for evaluation ofdiscontinuities at or near the surfaces.
9.4 If an electronic distance amplitude correctiondevice is used the reference response shall beequalized at least 50 percent of full screen height overthe distance range employed in the examination.
9.5 When reflector is located at 1/2 T a three pointDAC curve need to be established covering theexamination range.
9.6 For straight beam examination the straight beamprobe is positioned for maximum response from thehole that gives the highest amplitude. The sensitivitycontrols of the unit are to be adjusted to provide 80percent of full screen height. The probe shall bepositioned for maximum responses from the holes andthe peaks of the indication shall be marked on thescreen. The peaks are smoothly connected andextended through the thickness to provide the distanceamplitude curve from the side drilled holes.
10 TRANSFER CORRECTION
10.1 A correction in instrument sensitivities isrequired when the geometry of the material underexamination and calibration block are different.
10.2 Transfer correction shall be achieved byemploying two angle probes of the same type oneacting as a transmitter and the second as a receiver.The probes are directed to each other for a thoroughtransmission echo at one skip distance on thecalibration block and the scanning surface of themember to be examined for maximum response to 80percent of full screen height. The difference inamplitude control settings shall be added to thesensitivity settings of examination.
IS 15531:2004
11 PREPARATION FOR EXAMINATION
11.1 A cross-sectional drawing of joint showing thefusion faces as designed shall be prepared.
11.2 Where the joint geometry changes significantlyaround the circumference of the joint at least twocross-sectional drawings shall be made namelylongitudinal and transverse with respect to the axis ofthe large diameter component.
11.3 The ultrasonic operator shall have details ofcounter bore employed and take this into account whenexamining the weld. The extent of the counter-boreshall be designed long enough such that it does notinterfere with the examination.
11.4 The minimum length of unobstructed straightportion necessary on both sides of the w~ld, forscanning,shall be parent material thickness , ~US20
mm.
12 EXAMINATION COVERAGE
12.1 The full length of the weld shall be examinedalong a number of parallel scan lines across the widthof the weld and heat affected zone.
12.2 The pitch of the scan lines shall not exceed 90percent of the crystal width perpendicular to thedirection of the scan.
12.3 The rate of probe movement shall not exceed150 mm/s.
12.4 During scanning a slight oscillatory rotationalmovement upto 10° on either side of the normal to theweld axis shall be accomplished.
13 PROBE POSITIONS FOR SCANNING
13.1 Set-on Branch, Nozzle and Stub Welds
13.1.1 The side wall of component (see Fig. 2) shallbe scanned from the bore (scan P4) using a normalprobe of 4 MHz wherever possible. The probe issuitably adapted and profiled to fit the inner borecontact surface for examination and shall be chosenfor its minimum beam width at the fusion face.
13.1.2 The weld also shall be scanned between 1/2and 1 skip pesition from the out surface (scan P2).
13.1.3 Where there is no access for scanning from thebore, the weld shall be scanned from both outersurfaces of components A and B. Scans PI, P2 aresufficient from the outer surface of the stub.
13.2 Set Through Nozzle Welds
13.2.1 The side wall of component B (see Fig. 3)shall be scanned from Nozzle bore with a normal beamadapted to fit the contour of the bore.
3
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IS 15531:2004
Bore
Component A
E
P3
I# PI
Compon B‘2 Branch. Nozzle,
“HZZIFIG.2
Bore
SECTIONTHROUGH SET-ONBRANCH NOZZLEOR STUBWELD
~ -.“6
P5 - Comp “A’
Bore ~“ M[
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P4-,
FIG.3 SET-THROUGHNOZZLEWELDS
13.2.2 The side-wall of component A shall be scannedat angle within 10° of the normal using scan P2between 1/2 to 1 skip oppositions from the outersurface or scan P6 from the inner surface or acombination of both scans P1 and P5 depending uponthe material thickness and the consequent maximumbeam path distances required at the optimum angle andon access to the inner surface.
13.2.3 If the nozzle bore is in accessible the side-wallof component B shall be scanned using PI, P2 and P3to cover the full depth of the side wall at optimumangle (a).
13.3 Structural T Joints
13.3.1 The side wall of component A (see Fig. 4) shallbe scanned from the bore (if nozzle) with a normalprobe (Scan P7).
13.3.2 The side wall of component B shall be scannedat angle within 10° of the normal using scans P1, P2,P3 and P4. The above scans shall be from the toe ofthe weld upto 1 skip position form both surfaces ofcomponent B.
13.3.3 When the normal probe scanning P7 is notpracticable scans P5 and P6 from both sides 1 and 2of component A.
13.4 Cruciform Joints
13.4.1 The side wall of component A (see Fig. 5)shall be scanned from the upper and lower surfacesupto 1/2 skip position frctm side 3 or side 4. Scan P1and P4 or P5 and P%
13.4.2 Additional scans from side 1 or side 2 from theupper and lower surfaces also shall be made anexamination with a beam normal to the above fusionface is not possible. Scans P9 and P1O orP11 andP12.
13.4.3 The side-wail of components B shall be scannedfrom the outer surface of sides 3 and 4 upto 1 skipposition. Scans P1, P2, P5 and P6.
13.5 Oblique Node Joints
13.5.1 The circumference of the joint (see Fig. 6) shallbe divided into a minimum of 3 inspection zones.
4
IS 15531:2004
Comp B
P4 .
Side 2
P6
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Bore
FIG.4
F7
STRUCIVRALT JOINTS
Comp A
n Side 1
Pa
Side 3Pa P6 Side 4
Comp.
IP3
Pll -
u ‘ide2
FIG.5 SECTIONTHROUGH CRUCIFORMJOINT
13.5.2 The cross-sectional views through the jointand parent metal shall be used to select the optimumprobe angles and scanning surfaces.
13.5.3 The side wall of component B shall beexamined using a normal probe of minimum 4 MHzfrom the inner bore.
13.5.4 The side wall of component A shall be scannedup to full skip position from the available outer surfaceusing a minimum of two probe angles. Scans PI andP2 using minimum two angle probe.
14 EVALUATION
14.1 Recording of indicationsrespect to the reference level.
shall be made with
14.2 Any imperfection which causes can indication inexcess of 20 percent X)AC shall be investigated toestimate the nature of flaw that can be evaluated interms of acceptance standards.
15 PROCEDURE FOR DETERMINING THELOCATION AND SIZE OF THE FLAW
15.1 Flaw location
15.1.1 The position of the flaw within the weld maybe estimated from the position of the flaw echo on theCRT screen of oscilloscope. The distance between theflaw echo and the initial pulse as read from thecalibrated time base on the fluorescent screens is theactual beam path distance W of flaw. From the knownbeam angle of the probe used, the precise location ofthe flaw from the entry surface can be calculated using
5
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IS 15531:2004
p
Et
6A Plan View of Typical Oblique Node Joint
P2
PI
Comp B
P3
6C Sections Through Zone A
ZoneA
6B Side View of Node Joint ShowingScanning Zones
Bore
f 1
6D ‘Zone B’
P2
~cmp””‘c‘
6E 6,5 Zone ‘C’
FIG.6 OBLIQUENODEJOINTS
the formula t= Wcos et, where ‘t’ is the thickness ofcomponent on which the probe is placed within halfskip distance from the centre of the weld. When thecrystal is placed between half and full skip distance theformula is to be corrected as 2 t – Wcosa.Alternatively a flaw location rule or accurate sketchesmay be drawn to locate the flaws in a weld.
15.2 Size of the Flaw
15.2.1 In order to estimate the size of a flaw in anyparticular direction, the effective beam width at theflaw position has to be known. In the flaw size
investigation is to be determined first, whether theflaw is a large reflector or a small reflector. Largereflector is one that is larger than the sound beam at itsposition, and a small reflector’s is one that is smallerthan the sound beam at its position.
15.2.2 The size of a large reflector is determined byscanning the borders of the flaw with the ultrasonicbeam, by moving the prove from the centre of thediscontinuity until the height of the echo drops to 50percent of its original height (6 dB drop). Thisoperation is repeated to establish the boundary. This
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1
IS 15531:2004
is true for straight beam probes and in horizontal,vertical plane for angle beam probes.
15.2.3 Incaseof asmallreflector using angle beamprobes measurements of beam spread in the verticalplane shall be made on the side drilled holes as givenin Fig.1 forappropriate thickness atdifferent distancesfromthe shear weave probe. Toestimate the flaw sizethe probe is scanned so that the beam moves parallelto vertical direction and the distance within which theflaw echo amplitude in within 6 dB of the maximumdetermined, The flaw size is given by the differencebetween the probe distance moved to touch the edgesof the calibration hole and flaw in the weld multipliedby the cosine of the beam angle inside the medium.The calibration hole chosen shall be appropriate to thescanning path of the flaw.
pores, types elongated (worm hole) and planer flawsare usually differentiated by various scanningtechniques.
16.1.1 Isolated pores are indicated by a constant echosignal height using a swivel scan.
16.1.2 Elongated cylindrical flaws are indicated by aconstant signal height over a significant length and asharp peak for a shorter length in lateral and depthscanning depending upon the orientation of the flawto the weld axis.
16.1.3 Planer flaws produce sharp peaks whenscanned normal to their direction and drops suddenlywhen the prove is swiveled.
17 ACCEPTANCE
15.2.4 To obtain the boundary in the horizontal plane, Ultrasonic acceptance or rejection criteria forthe shear wave prove is moved parallel to the blind side individual butt welds shal] be based on a realisticdrilled hole described in 4.2. Until 6 dB from its appraisal of service requirements that shall bemaximum at different distances from the probe The established between the. purchaser and manufacturerdistance from the edge of the block to the position of on the basis of the quality that can normally becrystal subtracted from the depth of hole gives obtained in such welds.half-beam width. To estimate the flaw size in ahorizontal plane the probe is moved laterally so that 18 PERSONNEL REQUIREMENTS
the beam axis moves parallel to the lateral directionand the distance is within which the flaw echo Personnel performing ultrasonic examination to the
amplitude is within 6 dB of the maximum isrequirements of this article shall be qualified as
determined. The flaw size is given by the difference required by IS 13805.
between this dimensions an~ effective fi,dl beam 19 ~PoRTSwidth.
16 NATURE OF FLAWSA report of the examination shall be made. The reportshall include a record indicating the weld or volume
16.1 On determining the location and size of the flaw examined, the location of each ;ecorded reflector and
and from the knowledge of defects normally the identification of the operator who carried out each
encountered in different welding processes, an examination or part there of. The report shall be filed
estimate of the nature of flaw may be made. The and maintained in accordance with the referencingdifferent types may be classified, namely, isblated . code section.
*
6-
!’
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This Indian Standard has been developed from Dot: No. MTD 21 (3369).
Amendments Issued Since Publication
Amend No. Date of Issue Text Affected
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