Ansaldo NDT Specifications 22GRKW v1 0 (1)

8/11/2019 Ansaldo NDT Specifications 22GRKW v1 0 (1)

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TABLE OF CONTENT

1. OBJECT

2. FOREWORD

3. NDE SPECIFICATION

- ANNEX A Ultrasonic Examination of Materials

- ANNEX B Ultrasonic Examination of Weldments

- ANNEX C Radiographic Examination

- ANNEX D Liquid Penetrant Examination

- ANNEX E Eddy Current Examination of non-Ferromgnetic Materials


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1. OBJECT

This set of specifications cover the general requirements for the Non-destructiveExaminations (NDE) to be carried out during fabrication of Toroidal Field Case.

The present document contains the NDE methodologies applicable to thesubject component taking into account the geometry, the material, the thicknessrange of the raw material and the welded joints.

Therefore, the document gives the rules of the following NDE methodologies.

- Ultrasonic Examination of materials

- Ultrasonic Examination of weld

- Radiographic Examination

- Liquid Penetrant Examination

- Eddy Current Examination of non ferromagnetic materials


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2. FOREWORD

Following requirements are mandatory.

Any deviations to this specification, necessitated by special circumstances, shall

be submitted in writing to ITER (also called the Purchaser in the followingparagraphs) for written disposition.

This document applies only to the fabrication of Toroidal Field Cases

Components.

This document does not apply to maintenance, In-service Inspection, or otheroperation not strictly related to fabrication.

Acceptance criteria stated in this document shall be applied only if required byComponent Technical Specification document.

General requirement of this specification may be implemented or superseded

by the requirements of Component Technical Specification document.


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3. NDE SPECIFICATIONS

The Annexes A, B, C, D, and E contain the following Specifications:

- Ultrasonic Examination of materials

- Ultrasonic Examination of weld

- Radiographic Examination

- Liquid Penetrant Examination

- Eddy Current Examination of non ferromagnetic materials


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ANNEX A

ULTRASONIC EXAMINATION OF MATERIALS


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TABLE OF CONTENTS

1.0 SCOPE

2.0 REFERENCE DOCUMENTS

3.0 GENERAL

4.0 EQUIPMENT

5.0 CALIBRATION BLOCKS

6.0 SURFACE PREPARATION

7.0 PERSONNEL QUALIFICATION

8.0 CALIBRATION METHODS

9.0 CALIBRATION AND RECALIBRATION REQUIREMENTS

10.0 SCANNING REQUIREMENTS

11.0 QUALITY LEVEL

12.0 ACCEPTANCE CRITERIA

13.0 REPORTING CRITERIA

14.0 REPAIR AND RETEST

15.0 REPORT

TABLES


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1.0 SCOPE

This specification covers general requirements for the straight and angle beamultrasonic examination of plates, bars, forgings, and tubing in austeniticstainless steel. The requirements herein are intended to supplement those

specified in the ASME Boiler and Pressure Vessel Code.

The applicable Code issue and other requirements will be specified in theequipment specification or procurement document.

This process specification is intended as a guide to the Supplier to prepare the

NDE procedure specifications. The Supplier specifications shall be approved bythe Purchaser prior any NDE being performed.


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2.1 ASME Boiler and Pressure Vessel Code Section V Non-destructiveExamination.

2.2 EN 473 Qualification and certification of NDT personnel General principles.July 1993.

2.3 Additional documents that may be referred in design specification, drawings

and/or procurement documents.


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3.0 GENERAL

3.1 ULTRASONIC EXAMINATION PROCEDURE

Before testing begins, the Supplier shall prepare ultrasonic examinationprocedures and drawings or sketches detailing the essential variables of theexamination, including equipment calibration and acceptance standards. As aminimum, the following parameters and requirements shall be detailed in the

procedure.

a. The scope of the examination describing in detail the material to beinspected, e.g. sizes, geometry, quality level, etc., and the stage or stagesof manufacture at which the examination will be conducted.

b. The degree of surface preparation and description of the finish of the

surfaces to be examined.

c. The mode(s) of sound propagation and test angle(s) to be used.

d. The ultrasonic test System including instrument, transducer types,materials, and sizes. Beam angle in the material as measured on an IIW

(International Institute of Welding) or equivalent reference block shall benoted for contact testing methods. For immersion testing methods, the

angle of incidence and the water path distance shall be noted. The angle ofincidence is that included angle between the direction of the transmitted

wave and the normal to the interface at the point of incidence. The waterpath distance is that distance travelled by the transmitted wave in water.

e. A detailed description of calibration blocks including types, location, sizes,and depths of reference reflectors placed in each block. This descriptionshall be supplemented by a detailed sketch of the calibration block(s).

f. A detailed description of the instrument calibration procedure for each scan

and/or type of test including a sample copy of the calibration data sheet.

g. Type of couplant used and cleaning procedure employed.

h. The direction(s) and extent of scanning. The speed of transducer

movement, the amount of overlap between scans, and the test systemsensibility during scanning shall also be noted.

j. Test frequencies.

k. Qualification and certification of the personnel performing the test.


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i. Specific criteria for acceptance and/or reporting results. A sample copy of

the recording sheet shall also be provided.

l. Automatic alarm, recording equipment, or both, if used.


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Transducers shall be used at their rated frequencies.

4.3 COUPLANT

Glycerine or an equivalent shall be used as a couplant in sufficient quantity tomaintain continuous acoustic coupling between the search unit and test piece,when using the contact method.

If the immersed method is used, the workpiece and the search unit shall beimmersed in a container of couplant (usually water). Couplant for use on

stainless steel shall contain less than 15 ppm chloride, 10 ppm fluoride and 100ppm sulphur.

Other couplant materials may be used with prior approval, if guarantees of

complete removal after testing are provided. Couplant for use on stainless steelshall contain less than 15 ppm chloride, 10 ppm fluoride and 100 ppm sulphur.

After testing ends, the workpiece shall be rinsed with water grade in accordancewith cleanliness classification. .


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5.0 CALIBRATION BLOCKS

5.1 GENERAL

The Supplier shall provide the standard calibration blocks necessary to fullyrepresent the various thickness, geometry, acoustical characteristic, and otherparameters of the production parts.

Calibration test metal distances to reference reflectors shall be sufficient toassure the calibration criteria extend through the complete volume to be

examined.

5.2 MATERIAL

Standard calibration blocks shall be fabricated from production material, wherepossible, or from material of the same specifications, product form, heat-treat

condition, thickness and shape. Whether fabricated from production material orequivalent material, the blocks shall represent to the extent possible the same:

a. Production form (rolled, forged, cast, etc.).

b. Material condition: composition or grade, heat treatment includingtemperatures, times and cycles.

c. Material size, shape, configuration and curvature.

5.3 SURFACE FINISH

The surface finish of the calibration block shall be no better than that of the

parts being examined.

5.4 REFERENCE REFLECTORS

The following reference reflectors shall be placed in calibration blocks or in

production material:

- Drilled Holes - Drilled holes shall be flat bottom holes (FBH) or side drilled(SDH). Required hole diameters for the various quality levels are given in

Tables 1 through 4.


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- Notch Standards - Notch standards shall be 60 to 75 degree included angle,

25 mm long V-notches, located at least 25 mm from any edge or comer.Required notch depths for the various quality levels are given in Table 1

through 4.


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Contact surfaces shall be free of base scale, dirt, paint, weld spatter, or anyother foreign material that might interfere with the free movement of the searchunit or impair efficient transmission of ultrasonic soundwaves into the test piece.

Surface finish shall be RA = 6.3 micron (250 micro in) or better.


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Personnel performing NDE under this specification shall be certified inaccordance with European Standard EN 473 (see 2.3).


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8.1 STRAIGHT BEAM

8.1.1 Back Reflection

Adjust instrument sensitivity to obtain an 80 percent of full screen height first

back refection from the apposite side of the test specimen in an indication freearea.

8.1.2 Flat Bottom Hole (FBH)

A flat bottomed hole shall be drilled into the workpiece or calibration bock to a

depth of 19 mm or one half the part thickness, whichever is smaller, in materialsup to 150 mm thick and to a depth of 32 mm in materials of a thickness greater

than 150 mm. Adjust the instrument controls to obtain a reflection of 75-80percent of full screen height from the flat bottomed hole. This is the 100 percentreference level.

8.1.3. Side Drilled Hole (SDH)

A side drilled hole shall be drilled into the workpiece or a calibration block to a

minimum depth of 75 mm. The test distance to the side drilled hole shall assurecomplete volumetric coverage of the part under examination. Adjust the

instrument controls to obtain a reflection of 80 percent of full screen height fromthe side drilled hole. This shall be the 100 percent reference level.

8.1.4. Flat Bottom Hole and Side Drilled Hole Distance-Amplitude Correction:

Establish the distance-amplitude curve (DAC), 100 percent reference levelcurve through the peak responses from the reference holes placed such thattest distances equal _ T, _ T and _ T (where T = thickness of part), using 80percent of full screen height from the reference hole producing the largestreflection as the primary reference point.

8.2 ANGLE BEAM

8.2.1 V-notches


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Establish the distance-amplitude curve (DAC), 100 percent reference line

through the peak responses of the required notches at the hail node and fullnode positions using 80 percent of full screen height from the notch resulting in

the largest reflection as the primary reference point.

If the notch at the full node position cannot be detected, the response from thenotch at the half node position shall represent the 100 percent reference level.


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9.1 CALIBRATION REQUIREMENTS

Calibration shall include the complete ultrasonic system (search units,contoured wedges, cables, couplant, operator, instruments, power supply. orother component of this system). Any change in this system shall be cause forre-calibration.

9.2 RECALIBRATION REQUIREMENTS

Calibration shall be checked at regular intervals, four hours maximum,throughout the inspection period. If during any calibration check, it is determinedthat changes in sweep calibration exceeding 10% and/or a decrease in

amplitude exceeding 20% of full screen height or 2 dB have occurred, thecomplete ultrasonic system shall be recalibrate and all material examined

subsequent to the last acceptable check and calibration shall be re-examined.

9.3. AUTOMATED TESTING TECHNIQUES

For automated testing techniques calibration of the complete ultrasonic system

shall be done with the calibration standard or search unit or both moving in thesame manner, in the same direction, and at the same speed as will be used

during the examination.


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Scanning shall be performed at a gain setting in the range 2x to 5x calibration(+ 6 to + 14 dB). Evaluation shall be performed at the calibration reference level.

The scanning rate shall not exceed 125 mm of search unit movement persecond unless calibration is verified at scanning speed.

Scanning shall be conducted aver 100% of the designated test surface or

surfaces unless otherwise specified, e.g., on a grid basis in the contact orpurchase order. All scanning shall be conducted with a minimum of 15% of

transducer overlap.


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11.0. QUALITY LEVEL

Requirements for the various quality levels are listed in Table 1 through 4.

- Quality level A is given in Table 1.

- Quality level B is given in Table 2.

- Quality level C is given in Table 3.

- Thin wall tubing (2.5 mm wall, maximum), quality level D is given in Table

4.

Quality level A, given in Table 1, and Quality level D, given in Table 4 aremandatory for the TF Coil Cases.

Quality level B, given in Table 2, and Quality level C, given in Table 3 areapplicable when required by Component Technical Specifications.


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12.1 BACK REFLECTION

When calibrated to a back reflection, the part will be rejected if longitudinalwave examination results in one or more discontinuities which produce a loss ofback reflection to 5 percent or less of full screen height. The exception to thisrequirement is a laminar discontinuity in plates where paragraph 12.1.2 is

applicable.

12.1.1 Non parallel surfaces

Any loss of back reflection caused by non-parallel surfaces, changes in partgeometry, and/or surface irregularities shall not be caused for rejection.

However, tests must be conducted and documented to prove the loss of backreflection is a result of the above causes.

12.1.2 Laminar discontinuities in plates

Laminar discontinuities in plates are subject to rejection if they produce acontinuous total loss of back reflection accompanied by indications on the same

plane that cannot be encompassed with a circle whose diameter is 75 mm or _the plates thickness whichever is larger, unless specified otherwise in

applicable Purchaser documents.

12.2 FLAT BOTTOM HOLE, SIDE DRILLED HOLE , V-NOTCH

When calibrated to a single flat bottom hole, side drilled hole, or V-notch, anydiscontinuity producing an indication amplitude equal To or exceeding that of

the 100 percent reference bevel shall be cause for rejection.

12.3 DISTANCE AMPLITUDE CURVE (DAC)

When calibrated to a distance amplitude curve (FBH, SDH, or V-notch), any

discontinuity producing an indication amplitude equal to or exceeding thereference curve shall be cause for rejection.

Individual flaws and multiple linearly aligned flaws whose indications equal or

exceed 50 percent of the calibration standard and exhibit the following aresubject to rejection.


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- In the case of individual flaws, any flaw which exhibits length greater than

or equal to _ to the thickness of part being examined or 50 mm. whicheveris larger. The length of the flaw shall be obtained by recording the position

and location as determined by _ the maximum amplitude for each end ofthe 2 flaws.

- In the case of linearly aligned multiple flaws, two or more flaws whose totallength exceeds _ T (50 mm maximum) in any 2T length, where 2T length istaken in the most unfavourable location relative to the indications beingevaluated. The length of the flaws shall be obtained by recording the

position and location as determined by _ the maximum amplitude for eachend of the flaw.


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All recordable indications as defined below shall be reported per paragraphs15.1.3 and 15.1.4 of this specification.

In the back reflection technique, any reduction of 50 percent or more of the backreflection amplitude shall be reported.

In the back reflection technique, any indications equal to or exceeding the

remaining back reflection shall be recorded.

In the back reflection technique, any area where a loss of the back reflection to5 percent or loss of full screen height occurs shall be recorded. -

All discontinuities producing indication amplitudes equal to or exceeding 50percent of the 100 percent reference level shall be reported.

All discontinues which produce indications which are continuous on the same

plane regardless of amplitude and found over an area larger than twice themajor axis of the search unit shall be reported. The extent of such an indicationshall be accurately measured and reported along with variation in amplitude.


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Unless otherwise specified, rejectable defects may be removed and repairedusing a repair procedure approved by the Purchaser, provided that the repairedarea is retested and complies with all provisions of this specification, the

Purchase order, and the appropriate drawings.


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15.0 REPORT

The Supplier shall prepare a report of all ultrasonic examinations which shallinclude at least the following:

- Date of test, operator, NDE personnel certification level, and other pertinentinformation of that nature.

- All procedures and equipment shall be identified sufficiently to permit

duplication of the examination. This shall include calibration data and anysignificant changes in subsequent re-examination following repair.

- A marked-up drawing or sketch, Including the part or area examined, theitem or piece number and other information including reportable indicationsmapped as to location, extent, size, etc. The drawing or sketch shall alsoshow the reference axes and planes for subsequent relocation purpose.

- A record of the reportable indications showing the maximum amplitude

obtained, the location, extent, and orientation with the part, etc., shall bepresented in sufficient detail to permit evaluation of all discontinuities.

- A record of repaired areas as well as the results of the re-examination of

these areas.

- Items accepted or rejected.


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TABLE 1

QUALITY LEVEL A

Scans Required Reference Standard Reflectors

Product Form Straight Beam Angle Beam Straight Beam Angle Beam Drilled Hole Dia Notch Depth

Plate 100 percent of one major surface

100 percent intwo directionsperpendicular toeach other on onemajor surface

Back reflection orFlat Bottom Holesas required bycontract

V Notches 0.4 mm for each 6mm of thenominal thicknessof the plate orfraction thereof toa max. of 3 mm

3 percent of thenominal sectionthickness to amaximum of 6mm

Round Bar andForgings

100 percent radialand 100 percentaxially from bothends (seefootnote 1)

(see footnote 2) Flat Bottom Holesor Side DrilledHoles

V Notches 0.4 mm for each 6mm of thethickness of theforgings at thetime ofexamination, o rfraction thereof toa max. of 3 mm

3 percent of thethickness of theforgings at thetime ofexamination, to amaximum of 6mm

Bar and Forgings(other than round)

100 percentaxially from bothends and fromtwo perpendicular

sides (seefootnote 1)

(see footnote 2) Flat Bottom Holesor Side DrilledHoles

V Notches

Ring and HollowForgings Forged and BoredTubing over 7.6mm wall thickness

100 percent radialfrom OD, and 100percent axiallyfrom one end (seefootnote 1)

100 percent in 2circumferentialdirections fromOD and/or ID on afull or half nodebasis asnecessary toachieve 100inspection (seefootnote 2)

Flat Bottom Holesor Side DrilledHoles

V Notches

Tubing and Pipeover 2.5 mm wallthickness

Not required 100 percentcircumferential in2 directions and

100 percentaxially in twodirections

Not required V Notches Not applicable 5 percent of nominal wallthickness or 0.10

mm whichever islarger

Note (1) Forging having length/diameter or length/thickness ratios greater than 6/1 shall be examined axially from both ends. Forgingshaving length/diameter or length/thickness ratios greater than 12/1 shall be examined per footnote 2. Section of forgings havinglength/thickness ratios greater than 6 to 1 shall be examined per footnote 2.

Note (2) Forging which cannot be examined axially using a straight beam shall be examined in both axial directions with an angle beamtechnique. Use a 60 degrees V Notch(es) for calibration.


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TABLE 2

QUALITY LEVEL B



Plate 100 percent of one major surface

100 percent intwo directionsperpendicular toeach other on onemajor surface


V Notches 0.8 mm for each 6mm of thenominal thicknessof the plate orfraction thereof toa max. of 6 mm

3 percent of thenominal thicknessof the plate to amaximum of 6mm


100 percent radialand 100 percentaxially from oneend (see footnote1 of Table 1)

(see footnote 2 ofTable 1)


V Notches 0.8 mm for each 6mm of thethickness of theforgings at thetime ofexamination, o rfraction thereof toa max. of 6 mm

3 percent of thethickness of theforgings at thetime ofexamination, to amaximum of 6mm

Bar and Forgings(other than round)

100 percentaxially from oneend and from twoperpendicular

sides (seefootnote 1 ofTable 1)



V Notches


100 percent radialfrom OD, and 100percent axiallyfrom one end (seefootnote 1 ofTable 1)

100 percent in 2circumferentialdirections fromOD and/or ID on afull or half nodebasis asnecessary toachieve 100percent inspection(see footnote 2 ofTable 1)


V Notches

Tubing and Pipe

over 2.5 mm wallthickness

Not required 100 percent

circumferential in2 directions and100 percentaxially in twodirections

Not required V Notches Not applicable 5 percent of

nominal wallthickness or 0.10mm whichever islarger


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TABLE 3

QUALITY LEVEL C



Plate 100 percent of one major surfaceunless gridscanning isspecified bycontract

100 percent intwo directionsperpendicular toeach other on onemajor surfaceunless gridscanning isspecified bycontract


V Notches 6 mm for each 25mm of thenominal thicknessof the plate orfraction thereof toa max. of 12 mm

The lesser of 5percent of thenominal thicknessof the plate or 10mm


100 percent radialand 100 percentaxially from oneend. (see footnote1 of Table 1)



V Notches 6 mm for each 25mm of thethickness of theforgings at thetime ofexamination, o rfraction thereof toa max. of 12 mm

The lesser of 5percent of thethickness of theforging at the timeof inspection or10 mm

Bar and Forgings

(other than round)

100 percent

axially from twoperpendicularsides

(see footnote 2 of

Table 1)

Back reflection or


V Notches


100 percent radialfrom OD, and 100percent axiallyfrom one end (seefootnote 1 ofTable 1)

100 percent in 1circumferentialdirections fromOD and/or ID on afull or half nodebasis asnecessary toachieve 100percent inspection(see footnote 2 ofTable 1)


V Notches

Tubing and Pipe

over 2.5 mm wallthickness

Not required 100 percent

circumferential in2 directions

Not required V Notches Not applicable 5 percent of

nominal wallthickness or 0.10mm whichever islarger


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TABLE 4

QUALITY LEVEL D

THIN WALL TUBING (2.5 mm IN WALL THICKNESS, MAXIMUM)



Class 1:

Thin Wall Tubing(less than 2.5 mmin wall thickness)

See Note 1

Not required 100 percentcircumferential intwo directions

Not required V Notches Not applicable 5 percent wallthickness, ODnotch length shallbe equal to 3 mm.Notch located onID may be of anylength greaterthan transducerdiameter

Class 2:

Thin Wall Tubing(less than 2.5 mmin wall thickness)

Not required 100 percentcircumferential intwo directions.100 percentaxially in twodirections

Not required V Notches Not applicable 5 percent wallthickness, ODnotch length shallbe equal to 3 mm.Notch located onID may be of anylength greaterthan transducer

diameter

Note (1) Ultrasonic testing must be augmented by Eddy Current Testing


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ANNEX B

ULTRASONIC EXAMINATION OF WELDMENTS


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TABLE OF CONTENTS

1.0 SCOPE


3.0 GENERAL

4.0 EQUIPMENT

5.0 REFERENCE BLOCKS






11.0 EVALUATION





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1.0 SCOPE

The pulse-echo ultrasonic test methods described herein shall be employed asa complement to radiography in the inspection of welds and heat affected zonesof Toroidal Field Coil Cases. The objective of this specification is to achieve

reliable detection and evaluation for acceptance of metallurgical and otherdiscontinuities in the welds (WMZ) and heat affected zones (HAZ) of primarypressure boundary components made in austenitic stainless steel.


This process specification is intended as a guide to the Supplier to prepare theNDE procedure specifications. The Supplier specifications shall be approved bythe Purchaser prior any NDE being performed.


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2.3 Handbook on the ultrasonic examination of austenitic welds Compiled by the

COMMISSION V Testing, Measurement, and Control of Welds of TheIntentional Institute of Welding.

2.4 Additional documents that may be referred in design specification, drawingsand/or procurement documents.


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3.0 GENERAL

3.1 ULTRASONIC EXAMINATION PROCEDURE

Before testing begins, the Supplier shall prepare ultrasonic examinationprocedures and drawings or sketches detailing the essential variables of theexamination, including equipment calibration and acceptance standards. As aminimum, the following parameters and requirements shall be detailed in the

procedure.

a. The scope of the examination describing in detail the material to beinspected, e.g. sizes, geometry, quality level, etc., and the stage or stagesof manufacture at which the examination will be conducted.

b. The degree of surface preparation and description of the finish of the

surfaces to be examined.

c. The mode(s) of sound propagation and test angle(s) to be used.

d. The ultrasonic test System including instrument, transducer types,materials, and sizes. Beam angle in the material as measured on an IIW or

equivalent reference block shall be noted for contact testing methods. Forimmersion testing methods, the angle of incidence and the water path

distance shall be noted. The angle of incidence is that included anglebetween the direction of the transmitted wave and the normal to the

interface at the point of incidence. The water path distance is that distancetravelled by the transmitted wave in water.

e. A detailed description of calibration blocks including types, location, sizes,and depths of reference reflectors placed in each block. This descriptionshall be supplemented by a detailed sketch of the calibration block(s).

f. A detailed description of the instrument calibration procedure for each scan

and/or type of test including a sample copy of the calibration data sheet.

g. Type of couplant used and cleaning procedure employed.

h. The direction(s) and extent of scanning. The speed of transducer

movement, the amount of overlap between scans, and the test systemsensibility during scanning shall also be noted.

j. Test frequencies.

k. Qualification and certification of the personnel performing the test.


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i. Specific criteria for acceptance and/or reporting results. A sample copy of

the recording sheet shall also be provided.

l. Automatic alarm and recording equipment, or both, if used.

3.2 TIME OF EXAMINATION

The ultrasonic examination of primary pressure boundary welds may beperformed following completion of all manufacturing and fabrication procedures

including final stress relief or other final heat treatment, coincident with finalradiographic inspection.

3.3 EXAMINATION REQUIREMENTS

Ultrasonic examination of the entire volume of the weld and heat affected zones(HAZ) is required at equivalent detectability levels in at least two (2) directions

perpendicular to the long axis of the weld and in two directions perpendicular(approximate) to the transverse plane of the weld. Both the shear and

longitudinal (compression) modes of sound propagation and/or a combination ofboth may be applied as required by the part size and contour, as well as the

weld shape, location and orientation to achieve the stated objectives. Forevaluation purposes, the weld and HAZ shall be examined in as many ways anddirections as necessary to define the extent and nature of a questioned(reportable, recordable) condition.

Angled projection of the ultrasonic sound beam shall be considered the primarymethods of examination. The sound beam angles shall be chosen so as to

provide as near-normal incidence as possible to the expected flaw orientationswhile maintaining a short probe to flaw distance; see Table 1 for suggestedanglethickness relationships. (Note: for flaw evaluation the sameangularthickness relationships (Table 1) may be applied to heavy wall (e.g.

150 mm to 300 mm) welds by considering the weld thickness in increments or

layers equivalent to the material thickness listed, measured from designatedtest surface).

The length of material (test metal distance) examined using either angle orstraight beam procedures in the shear or longitudinal modes shall not exceed

the distance from the search unit to the farthest notch or reference reflectorused in calibration.See also 4.2.2.


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TABLE 1

Sound Beam (Shear Wave) Angle Thickness Relationships

Material (Base) Primary Beam Angle Secondary

Thickness (In Material) Beam Angle

6 mm to 75 mm 70 45

75 mm to 150 mm 60 45

150 mm to 225 mm 50 60

Over 225 mm 45 (+ 5 - 0) 60


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4.0. EQUIPMENT

4.1 ULTRASONIC INSTRUMENT

The ultrasonic test equipment shall be capable of transmitting, receiving anddisplaying signals at set frequencies of 1.0 to 5.0 MHz. The test equipment shallhave linear response within 5% for at least 75% of the vertical screen heightand for at least 75% of the horizontal sweep length, determined using either the

methods prescribed in ASTM E 317 or similar methods designed to provideequivalent data. Signal attenuator, if used, shall be accurate over the range

used to 10% of the nominal attenuation ratio. If the instrument is equippedwith an electronic distance amplitude correction device, the primary referenceresponse shall be equalised at 75% of the linear screen height over thedistance range to be employed in the longitudinal wave and/or shear caveexaminations.

4.2 SEARCH UNITS

The major variables to be considered when selecting a probe are:

1) wave type;2) angle;

3) frequency;4) type of probe;

5) size and geometry of probe and component.

4.2.1 Wave Type

The use of conventional shear wave probes shall always be considered first, ifthe signal-to-noise ratio is insufficient for an effective inspection, special probes

like refracted longitudinal angle beam probes, including the surface wave type

need to be used.

4.2.2 Probe Angle

The probe angle shall be selected to be suitable for the expected defectorientation. This means that if possible, the incident angle shall be chosen to

strike a defect perpendicularly for maximum echo amplitude.

For weld examination, it is therefore necessary to know the weld geometry priorto and after welding; particularly the details of the weld root if this is not

machined or ground flush (full dressed).


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The entire volume of weld and fusion zone can be covered with at least twoangles of incidence as shown in Figure 4.1.

Figure 4.1 - Volumetric Examination

However, this approach does not take into account the above consideration ofpreferred beam to flaw orientation. Nevertheless, in some cases it may only benecessary to examine inner and outer surfaces of the weld to demonstratefitness-for-purpose from a fracture mechanics point of view. In this case, theuse of an additional surface wave probe may be considered. If optimized flawdetection over the whole thickness is required, then a range of probe anglesbetween 60 and 70 should be included to detect lack of sidewall fusion.


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In some cases, one would also consider using 45 angle probes to inspect the

root area in relatively thick welds. However, if the weld penetration is not groundflush, geometrical or false echoes may be generated with a 45 probe, and for

that reason, a probe with a larger angle (for instance 60) may be used toimprove the identification of echoes defect. Therefore, the choice of probe angle

largely depends on the weld preparation and weld surface condition, It shouldalso be remembered that examination at more than half- skip distance is notvery effective due to mode conversion effects at the backwall. To reach thelower part of the weld with large angle probes requires a long sound path andthis can also reduce the effectiveness of the examination.

This is influenced by the total attenuation and is highly material dependent. If all

these different effects are considered, it can generally be concluded that:

- For thin welds and for the near surface area (at the scanning side) of thickwelds, large angle probes provide the best results.

- For all welds, the weld surface shall be dressed smooth to enable the probe

to be scanned across the weld.

- If the weld is narrow, then surface wave probes can still provide a goodexamination of the upper part of the weld.

- Surface wave probes are also well suited for detection of surface breakingdefects and near surface defects in wide welds, provided the welds are full.

As the surface wave probes do not have a significant dead zone, their use canbe considered under all circumstances where the required working depth doesnot extend beyond about 10mm.

For detection of deep lying defects in thick welds, steeper angles must beselected and a compromise found between optimum incidence on flaws andscanning distance. This may result in the selection of a range of angled probes.

Also, a tandem arrangement of longitudinal wave probes or a combination of alongitudinal and shear wave probe(s) should be considered as suggested inFigure 4.2.

As a result of the above approach, thick welds are often considered divided into

thickness zones and examined with different probes whereby each zone isinspected by the most appropriate probe(s)


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Figure 4.2 - Tandem Inspection

4.2.3 Probes Frequency

The frequencies used are generally in the range of 1 to 5 MHz. The interactionbetween grain-size and wavelength dominates the selection of the bestfrequency to optimize signal-to-noise ratio.

Ultimately, the frequency selected is a compromise between the resolution

required and signal to noise ratio. This often leads to the use of probes with alarge bandwidth. In special cases, a selectable bandwidth for the ultrasonicpulse might be appropriate.

Equipment bandwidth should be appropriate to probe type.

In practice, it is found that for welds over 25mm thickness and cast material,frequencies of 2 and 1 MHz are predominantly used.

For welds below 25 mm thickness, the frequencies most commonly used are 4

and 2 MHz.

The side drilled holes in the probe characterisation block provide a means forcomparing different probes with respect to signal-to-noise ratios. The signal isthe echo of a side-drilled hole, whereas the noise can be taken as themaximum level of material grain indications occurring at the same sound path

as the side-drilled hole.

Clearly the signal-to-noise ratio of a probe is not a constant, but dependent onsound path. The signal-to-noise ratio found on the probe characterisation blockrepresents the nominal condition and can change considerably in the presenceof a weld, and it should also be determined on the reference block.


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4.2.4 Probes Type

The main probes in use for austentic weld inspection are:

- single crystal probes;

- twin crystal probes with separate transmitter and receiver crystal (TR).

The selection is often arbitrary.

In order to decrease the number of probes and inspection zones, single crystal

probes are favoured because they do not show so pronounced a distanceamplitude curve as for TR probes.

On the other hand, many single crystal probe designs show a long acousticdead zone, which decreases the efficiency of surface and near surfaceexamination. Occasionally, single crystal point or line-focussing probes can be

are used, particularly where the more conventional probes described above fail.

The use of such purpose built focussing probes is critical because they willbehave only as calculated if all aspects of the examination such as surface

roughness, geometry, and acoustic material properties. etc., are kept withinnarrow tolerance limits.

The above remarks are valid for both immersion and contact techniques.Immersion testing, in particular, requires a very stable and precise mechanicalarrangement because the refractive index is roughly twice that for contactprobes. As a result, small variations in angle of incidence cause considerablevariations in the angle of refraction.

4.2.5 Size and Geometry of Probe and Component

Apart from the beam characteristics necessary for the examination, the probe

shall be of a size which allows manual examination with good acoustic coupling.

Thus, coupling involves an interaction between probe size, roughness, and thegeometry of the component.

If the probe dimension W fails to meet the requirement R < W2 / 4 (where A isthe radius of the curved surface under examination and W is the probe

dimension, in length or width), dimensions in mm, or the coupling gap exceeds0.5 mm, the probe shoe shall be adapted to the geometry of the component.

This can be done by machining or by applying grinding paper on the componentand matching the probe shoe to the component curvature.


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Care shall be taken when operating from curved surfaces. The probe

performance shall be checked after modification of the probe shoe by trials onthe appropriate reference blocks. The probe index point and/or nominal angle

may change if shoe adaptation is not carried out properly.

4.3 COUPLANT

Liquids couplant such as glycerine or water shall be used to complete thesearch unit or probe to the item to be examined. Other couplant materials may

be used with prior approval, if guarantees of complete removal after testing areprovided. Couplant for use on stainless steel shall contain less than 15 ppm

chloride, 10 ppm fluoride and 100 ppm sulphur.

After testing ends, the workpiece shall be rinsed with water grade in accordancewith cleanness classification.


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5.0. REFERENCE BLOCKS

5.1 GENERAL

Because of the special effects of austenitic weld metal on ultrasound it isnecessary to produce a reference block in order to:

a) develop an examination procedure;

b) set a preliminary sensitivity level;c) assess the procedure;

d) help to demonstrate the effectiveness of the preliminary examinationprocedure before a definitive procedure is written.

The material from which the block is fabricated should have the samecomposition as the material being examined, i.e. chemical analysis, product

form, fabrication, procedure, heat treatment, cooling rate.

The weld in the reference block should be similar to the weld being examinedand made using the same welding procedure. All variables should be respected,including those which may not be considered essential for the weldingprocedure qualification test pieces, weld preparation, weld position, heat input,

cooling rate, etc.

The geometry and surface condition of the scanning and reverse side of thereference block should be considered, both for the base material and for the

weld deposit. The reference block should generally contain known artificialreflectors, though in some cases, a weld containing real defects may be useful.

5.2 ARTIFICIAL REFLECTORS

Before machining artificial reflectors as described below, the reference block

should be examined by non-destructive methods such as penetrant testing,

ultrasonic testing (straight beam), and radiographic testing to detect possibleunwanted defects which would interfere with its use.

Side drilled holes (in combination with notches) are most commonly used as theartificial reflectors. Holes shall be drilled at regular depth intervals, e.g. 1/4, _

and 3/4 t (where t is weld thickness) for single crystal probes. For twin crystalprobes, which are effective over a particular depth zone, the holes shall be

located at the zone centre and the zone limits (6 dB). Altematively, when a setof twin crystal probes is applied, a series of holes distributed over the thickness,

say every 10 mm, may be used.


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The holes shall be drilled in the fusion zone of the weld to allow comparison of

the sensitivities when the beam passes through the full width of the weld andthrough base material only. In some cases, this may not be practicable, and

separate sets of holes at the weld centre line and within the base material maybe more suitable.

Flat bottom holes can also be used with the flat bottom perpendicular to eitherthe examination surface or to the nominal beam direction. In the latter case, theholes represent flaw detection by reflection from facets and shall be of smalldiameter.

Due to mode conversion (compression into shear) even in fine grain material, a

smooth notch sometimes produces only a small reflection. Hence, whenlongitudinal waves are applied with 45 probes, the use of notches (cornereffect) for sensitivity calibration is not advisable.

Figure 5.1 - Reference block with artificial defects situated at the weld centreline and in the parent metal

In all cases, it is recommended that in addition to the artificial reflectors in theweld, a similar set of reflectors be machined in the adjacent plate or pipe

material of the reference block, as shown in Figure 5.1. This is important in


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order to quantify the effects of the weld structure and to give a reference

reflector for the examination of the parent material near the heat-affected zone.

Drilled holes shall be used to establish reference levels and distance -amplitude correction data. The reference calibration hales shall be drilled

parallel to the contact surface of the reference block.

The locations and diameters of these holes shall be as given in Table 2.

In addition to the drilled hole calibration reflectors, a 75 ( 5) included angle

vee notch shall be provided in the reference block for flaw evaluation purposes.

The vee notch shall have an effective length of 25 mm, maximum and a depthof 3% of the production weld of test material thickness or 9.5 mm whichever issmaller. The notch shall be placed in the surface opposite the proposed primarytest surface of the reference block or production material if permitted.

TABLE 2

Material Thickness Hole Diameter (mm) Hole Location

Up to 25 mm Included 2.5 - _ T -

Over 25 mm Through 50 mm 3.0 - _ T -

Over 50 mm Through 100 mm 5.0 _ T _ T _ T




Over 250 mm 11.0 _ T _ T _ T


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6.0. SURFACE PREPARATION

All test surfaces shall be prepared by machining, grinding and/or polishing for adistance approximately equal to twice the weld thickness on both sides of theweld to be examined, or in limited accessibility situations, for a distance

approximately equal to twice the weld thickness onone side of the weld and tothe extent (two search unit width minimum) possible on the other side.

In all cases all the accessible weld metal surface shall be full dressed. Surfaces

finishes shall be of 6,3 micron (250 micro in) or better.

All test surfaces shall be free from loose scale, machining or grinding particles,paint, other foreign particles and any roughness that will interfere with freemovement of the search unit or probe. All test surfaces shall be sufficientlysmooth and free from waviness to permit a uniform test at the requiredsensitivity levels over the required areas; e. g., changes due to surface

conditions, of 15% or less in back refection amplitude when testing through thebase metal thickness using longitudinal wave straight beam techniques are

considered acceptable. Grooves, score marks etc. (for example: valleysbetween weld beads) are permitted in the flat surfaces, provided the widthdoes not exceed 10% of the effective diameter or width of the transducer andthe individual grooves or marks are separated by at least one diameter or width

of the transducer used.


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7.0 PERSONNEL QUALIFICATIONS



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8.0 CALIBRATION METHOD

Calibration shall be performed establishing a DAC curve by using a referenceblock.

8.1 SENSITIVITY SETTING

For sensitivity setting, the reference block and reference reflectors described in

5.0shall be used.

After selecting the probes for a particular wall thickness and weld geometry anddetermining their characteristics on the probe characterisation block (i.e. thecharacterisation blocks described in the Chapter 6 of the document Handbookon the ultrasonic examination of austenitic welds Compiled by theCOMMISSION V Testing, Measurement, and Control of Welds of The

International Institute of Welding), the examination sensitivity shall be set. Thisis done with the aid of the reference blocks shown in Figure 5.1 using side

drilled holes at the fusion face or at the weld centre line.

Where fusion face holes are used, two calibrations are to be performed perscanning surface:

a) by establishing the echo height of the side drilled holes, with the beam

passing through parent metal only (see Figure 4.1);

b) by establishing their echo height with the beam passing through the weldmetal (see Figure 4.1).

If centre line holes are used (see Figure 5.1), sensitivity setting from both sidesis not required unless dissimilar metals are welded together (e.g. cast andforged austenitic material).

Within the zone over which a particular probe will be used, the echoes from

each of the available holes is maximised. The highest echo should then be setto approximately 80% screen height. Then, without altering the gain setting, thepeaks of the echoes of the other holes are marked on the screen, and a DAC-curve is drawn to connect the points.

This is the 100% Distance Amplitude Correction (DAC) reference line.

In practice, the shape of such a curve can differ considerably from that obtainedon the probe characterisation block; especially when the beam passes through

the weld metal.


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It may sometimes be found that a different probe combination and/or zone

distribution are required from that previously chosen on the basis ofmeasurements on the probe characterisation blocks. For this revised probe

selection, a new set of DAC curves should be established on the referenceblock.

8.2 RECORDING LEVEL

The recording level is specified in terms of a percentage of the reference

reflector-response or the Distance Amplitude Correction (DAC) curve.Two additional curves (50% and 20%) shall be drawn.

The recording level in the appropriate depth zone should be at least 6 dB higherthan the maximum noise level in that depth zone.


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9.1 CALIBRATION REQUIREMENTS

Calibration shall include the complete ultrasonic system (search units,contoured wedges, cables, couplant, operator, instrument, power supply, orother component of the system). Any change in this system shall be cause forrecalibration.

9.2 RECALIBRATION REQUIREMENTS

Calibration shall be checked at regular intervals, four hours maximum,throughout the inspection period. If during any calibration check, it is determinedthat changes in sweep calibration exceeding 10% and/or a decrease in

amplitude exceeding 20% of full screen height or 2dB have occurred, thecomplete ultrasonic system shall be recalibrated and all material examined

subsequent to the last acceptable check and calibration shall ho re-examined.

9.3 AUTOMATED TESTING TECHNIQUES

For automated testing techniques calibration of the complete ultrasonic system

shall be done with the calibration standard or search unit or both moving in thesame manner, in the same direction, and at the same speed as will be used

during the examination.


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All scanning shall be conducted at speeds not exceeding 125 mm per second.Contact and coupling effectiveness during scanning shall be maintained bymonitoring structure noise levels, and reflections or by approved electronic

and/or mechanical devices included in the test equipment.

The area of the base metal through which the sound will travel in the anglebeam examinations shall be completely scanned with a straight beam (0

longitudinal wave) search unit to detect reflectors which might affect theinterpretation of angle beam results. Consideration must be given these

reflectors during interpretation of the weld examination results, but theirdetection is not a basis for rejection of the base material. The coarse grainaustenitic materials will require special fixture to accommodate the straightbeam and refracted longitudinal searching combinations needed to accomplishthis interpretative scanning.

10.1 LONGITUDINAL MODE SCANNING - (Straight Beam to 20)

The sections to be examined shall be scanned by moving the search unit alongand across a sufficient area so as to scan the entire volume of weld and heat

affected zones.

Scanning shall be performed at a gain setting in the range 2x to 5x calibration(+ 6 to + 14 dB). Evaluation shall be performed at the calibration reference level.

Scanning shall be conducted aver 100% of the designated test surface or

surfaces unless otherwise specified, e.g., on a grid basis in the contract orpurchase order. All scanning shall be conducted with a minimum of 15% oftransducer overlap.

Search unit holders, shoes, wedges, guides, etc., shall be used to maintain the

sound beam at the angle designated for the scanning operation.

NOTE: Shoes, wedges, guides, etc., must be included in the calibration.

10.2 ANGLE BEAM (Shear and Longitudinal Mode Scanning)

Place the search unit (properly coupled) on the prepared test surface adjacent

to the weld to be examined with the projected direction of the sound beamnormal to the long axis of the weld. Move the search unit to and from the weld in

a path normal to the axis of the weld.


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Search unit movement to and from the weld shall not be less than a distance

equal to twice the thickness of the weld with the scan path starting at the toe ofthe weld. This scanning procedure shall be repeated, to the extent possible,

from the apposite side of the weld.

Place the search unit (properly coupled) on the prepared test surface adjacentto the weld to be examined with the projected direction of the sound beam at aslight angle, see Table 3, with respect to the long axis of the weld.

TABLE 3

Search unit Direction for axial scanning

Scan Angle Weld Thickness

5 6 mm to 25 mm

5 - 10 25 mm to 75 mm

15 75 mm to 150 mm

15 - 20 Over 225 mm

Move the search unit along the weld maintaining the scan angle per Table 3 in

a path parallel to the axis of the weld. With each pass along the weld, index thesearch unit away from the weld a distance equal to a maximum of 75% of thetransducer (crystal) width until a width of test surface equivalent to the materialthickness is scanned along the entire length of the weld.

Reverse the projected direction of the sound beam, i.e. direct the sound beamin the apposite direction to that of previous Paragraph and repeat the angled

scanning procedure on the same side of the weld.

Repeat the previous described angled scanning procedures on the appositeside of the weld or to the extent possible if accessibility is limited.


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11.0 EVALUATION

11.1 ANGLE BEAM (Shear and/or Longitudinal Wave Mode)

Angle beam (shear and/or longitudinal wave mode) detected discontinuitieswhose indications exceed 20% of the DAC reference line for the particularthickness being tested shall be evaluated to the extent possible for size(determining maximum amplitude obtainable), extent, length, orientation,

location, shape and nature using larger and smaller sound beam angles, higherand/or lower test frequencies and other modes of propagation based on the

side drilled hole and vee notch references in the calibration block.

11.2 STRAIGHT BEAM (Longitudinal Wave Mode)

Longitudinal wave mode detected discontinuities whose indications exceed 20%of the DAC reference line shall be evaluated in the same manner outlined in

11.1.


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Acceptance criteria will be as follows.

- All imperfection which produce a response greater than 20% of the

reference level (100% DAC reference level) shall be evaluated as per 11.1, and evaluated in terms of the acceptance standards given in (a) and(b) below.

(a) Imperfection are unacceptable if the indications exceed the referencelevel amplitude and have lengths exceeding:

(1) 6.35 mm for tup to 19 mm inclusive;

(2) 1/3 tfor tfrom 19 mm to 57 mm inclusive;

(3) 19 mm for tover 57 mm.

Where t is the thickness of the weld being examined. If a weld joinstwo members having different thicknesses at the weld, t is the thinnerof these two thicknesses.

(b) Indications characterised as cracks, lack of fusion, or incompletepenetration are unacceptable regardless of length.


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The Supplier shall prepare a report of the ultrasonic examination which shallcontain the following:

a. All procedures and equipment shall be identified sufficiently to permitduplication of the examination(s) at a later date. This shall include initialcalibration data and calibration transfer test and dimensional data and anysignificant changes in subsequent re-examination following repair. The

procedures shall include at least the following information.

- Weld types and configurations tested including thickness dimensions.

- Automatic defect alarm and recording equipment or both if used.

- Special search units, wedges, guides, or saddles, if used.

- Automatic scanning mechanisms, if used,

- Stage of manufacture when test was made.

- The surface or surface from which the test was performed.

- Surface finish.

- Couplant.

- Mode and method (angles) used.

- Description of the calibration method and method of correlatingindications with defects.

- Scanning directions.

- Type and size of transducer and test frequency.

b. A marked up drawing or sketch indicating the weld(s) examined, the item orpiece number, and other information necessary to identify the weldment.

c. A record of the maximum amplitude, location, orientation, length, extent,shape and predicted nature of all discontinuities producing indications of

amplitude exceeding 90% of the applicable reference amplitude.

d. A record of the repaired areas as well as the results of the re-examinationof the repaired areas.


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Unless otherwise specified, rejectable defects may be removed and repairedusing a repair produce approved by the Purchaser, provided that the repairedarea is retested and complies with all provisions of this specification, the

Purchase order, and the appropriate drawings.


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ANNEX C

RADIOGRAPHIC EXAMINATION


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TABLE OF CONTENTS

1.0 SCOPE


3.0 GENERAL REQUIREMENTS

4.0 EQUIPMENT AND PROCESS

5.0 PREPARATION OF SURFACES TO BE RADIOGRAPHED


7.0 RADIOGRAPHIC INSPECTION SEQUENCE

8.0 TECHNIQUE

9.0 IDENTIFICATION AND MARKING

10.0 RADIOGRAPHIC REPORT

11.0 QUALITY LEVEL


TABLE 1


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1.0 SCOPE

This process covers procedure to be followed in radiographic testing ofmaterials for discontinuities as may be required by various Codes or by generalspecifications under which the equipment is being designed and manufactured.

The requirements herein are intended to supplement those specified in theASME Boiler and Pressure Vessel Code or other governing documents whereapplicable.


This process specification is intended as a guide to the Supplier to prepare theNDE procedure specifications. The Supplier specifications shall be approved bythe Purchaser prior any being performed.


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2.3 Additional documents that may be referred in design specification, drawingsand/or procurement documents.


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3.0 GENERAL REQUIREMENT

3.1 RADIOGRAPHIC EXAMINATION PROCEDURE

Before testing begins, the Supplier shall prepare radiographic examinationprocedures and drawings or sketches detailing the essential variables of theexamination, including equipment and acceptance standards. As a minimum,the following parameters and requirements shall be detailed in the procedure.

a. The scope of the examination describing in detail the material to be

inspected, e.g. sizes, geometry, quality level, etc., and the stage or stagesof manufactures at which the examination will be conducted.

b. The degree of surface preparation and. description of the finish of thesurfaces to be examined.

c. The radiographic test including: instruments, source of radiation, films,

intensifying screen, penetrameters.

d. Qualification and certification of the personnel performing the test.

e. Specific criteria for acceptance and/or reporting results.


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4.0 EQUIPMENT AND PROCESS

4.1 SOURCES OF RADIATION

Sources of Radiation: Either X-rays or gamma rays may be used. Maximumvoltage of the source of radiation shall be in accordance with the applicablesection of the ASME Code.

4.2. SENSING MEDIUM

4.2.1 Films

Radiographs shall be made only on non-flammable, fine grain (Type 1 or Type

2 of ASTM E-94) and high contrast radiographic film free of inherent flaw thatmay interfere with the interpretation of the radiograph except as noted in 8.4.1

(Betatron section).

4.2.2 Intensifying Screens

Metallic intensifying screens of approximately 0.15 mm thick shall be used in

the production of radiographs except that when radiographing various metalsequivalent to 6.35 mm or less of steel, it may be necessary to remove or not

use such screens in order to produce the best radiographs.Fluorescent type screens are prohibited.

4.2.3 Filters

Objectionable backscatter may be reduced by suitable filtration (filters of greater

atomic number than the material being radiographed).

4.3 PROCESSING

Film shall be processed in accordance with ASTM E-94, Part III.


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5.0 PREPARATION OF SURFACE TO BE radiographed

5.1 MATERIALS

All surfaces shall conform to applicable material specifications. Additionalconditioning may be applied to assure that surface irregularities cannot mask orbe conformed with discontinuities.

5.2 WELDS

When the ground flushing (full dressing) of the welded joints is not required forcarrying out other NDE (i.e. Ultrasonic Examination), all weld ripples or otherweld surface irregularities of joints, on both the outside and, where applicable,the inside, shall be removed by suitable mechanical processes to a degree such

that the resulting radiographic contrast due to remaining irregularities cannotmask or be confused with sub-surface discontinuities. Also, the weld metal shall

merge smoothly into the base metal surface. The finished surface ofreinforcement or butt weld should, have a reasonably uniform crown.

5.3 COMPONENTS

All components shall be free of base sand, oxides, etc. and should haverelatively smooth surfaces free from flash, scale and other surface irregularities

which could obscure internal defects.

NOTE: Any method that induces hot grinding when removing weld ripplesand surface irregularities shall not be used.


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6.0 PERSONNEL QUALIFICATIONS



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7.0 RADIOGRAPHIC INSPECTION SEQUENCE

Exploratory radiographic examination may be conducted at any point in theprocess schedule of a component to determine the presence of defects in areasusually encountered; such as, at points of high stress, abrupt changes in metal

sections, root of welds, questionable visual surface defects, etc., in order thatthe most economical corrective action may be taken to produce a qualitycomponent. After a major defect has been removed, the area should be radio-graphed in order to determine whether the removal of the defect is complete

before repairing. Repairs shall only be made by welders possessingqualifications required by contract.

Any repair welds radiographed shall be identified on the radiography by theletter R.

Specified radiographic examination shall be made on the component in the final

heat treated condition, if such heat treatment consist of solution annealing orquench hardening. Unless otherwise specified, radiographic examination shall

be made on the component or system in accordance with the time ofexamination requirements of the applicable code(a) rules.


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8.0 TECHNIQUE

8.1 SENSITIVITY

All radiographic examinations shall be performed by a technique capable ofindicating Image Quality Indicators (I.Q.I.) outline, identify numbers, and 2T holeor the slit. All I.Q.I. thickness shall conform to ASME Boiler and PressureVessel Code requirements.

Required quality level shall be 2% (2-2T) unless another level is agreed upon by

Purchaser and Supplier.

The two-film technique is recommended.

8.2 IMAGE QUALITY INDICATORS (I.Q.I.) DESIGN

I.Q.I. shall have a radiographic density equal to or less than that of the materialto be radiographed.

Hole-Type Image Quality Indicators (according to ASTM E-1025) shall be used.

If necessary, Wire-Type Image Quality Indicators (according to EN 462 Part 1 or

ASTM E-747) may be used, prior Customer written approval.

8.3 POSITION OF I.Q.I.

When possible, I.Q.I. shall be placed on the side nearest the radiation source.

When more than one exposure is made with the film and source, both outsidethe parameters shall be located on the inside surface of the component

adjacent to the area which the radiograph represents.

When a number of exposures are to be made with the source outside and thefilm inside, the I.Q.I. shall be placed on the outside surface nearest the source.When radiographing an assembly with the source located inside the component,the I.Q.I. shall also be located on the inside surface.

In cases where placement of the I.Q.I. on the source side is impractical without

cutting a hole in the wall of the component, the I.Q.I. may be placed on the filmside. (I.Q.I. placement shall be identified as to F for film side and S for

source side).


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At last two I.Q.I. shall be used, if possible, one at each end of the exposed

length for each exposure. One shall be placed parallel to and the otherperpendicular to the edge of the area under examination, and both shall be

approximately 6.3 mm away from the edge. The I.Q.I. shall be placed at thepoint of maximum obliquity between the source of radiation and the object, with

the small 1T holes being positioned at the point of greatest angularity. Forradiographs of welds, the I.Q.I. shall be placed on the base metal (see Figure8.1).

Figure 8.1 - Positioning of Hole-Type Image Quality Indicators and

identification markers

When the I.Q.I. is placed adjacent to a weld scan and the weld reinforcement isnot removed, a shim of the same radiographic density shall be placed under the

I.Q.I. such that the total thickness being radiographed under the I.Q.I. is thesame as the total thickness through the weld.

Where the thickness of the metal is not uniform, but does not vary by more than

20% of the maximum thickness or by more than 12 mm in section, whichever isthe lesser, over the area covered by a single radiograph, one set of I.Q.I. shall

be required as per Figure 8.1.

If the thickness of the metal covered by a single radiograph varies by more than20% of the maximum thickness or by more than 12 mm whichever is the lesser,suitably sets of I.Q.I. shall be placed at the thinnest and thickest portion beingradiographed.


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8.4 LIMITING DISTANCE

During exposure, the film shall be as close as practicable to the surface of the

object being radiographed.

The focus - film distances shall allow a geometric unsharpness (Ug) which notexceed the following:

Material Thickness, mm Ug Maximum, mm

under 50 0.50

50 through 75 0.75

over 75 to 100 1.00

greater than 100 1.80

Geometric unsharpness (see Figure8.2) is given by the equation: Ug = Ft / do

Where:

Ug = Geometric Unsharpness Ft / do

F = Size of the radiation source

t = specimen thickness, when in contact / do

do = source object distance


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Figure 8.2 - Geometric unsharpness

8.4.1 X - Rays

When using X-rays, the focus-film distance shall be not less than seven timesthe thickness of the metal being radiographed, and, in general, therecommended distance shall not be less than 900 mm except as follows:

When using 140 kV or lower voltage X-ray equipment it may be possible to

obtain satisfactory results with a 600 mm or even shorter focus film distance.The minimum focus-film distance with 1000 kV X-rays is usually 1800 mm.

However, when very loss currents are being used with the 1000 kV equipment,the size of the focal spot shall be correspondingly reduced which will permit


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shorter focus-film distances. Such techniques shall be determined during the

Qualification Test.

When a high energy type machine in the range of 10 to 25 MeV is employed, afocus-film distance of at least 230 mm is recommended. It is desirable to use

very fine grain film for steed thickness less than 150 mm and fine grain film forgreater thickness.

When radiographing flat surface at 250 kV or less, the focus-film distance shallbe not less than the largest linear dimension of the area being radiographed, but

not less than 900 mm.

For Betatron type machines, the linear dimension of flat surfaces that can beradiographed is determined by the beam angle and shall be proven by properlyplaced I.Q.I. at the extremities and central portion of such area.

For linear accelerator type machines having a 1 mm focal spot size, a focus-filmdistance vs. thickness being radiographed relationship as follows is

recommended:

Thickness, mm Optimum ffd, mm Minimum Acceptable ffd, mm

250 1420 710

380 1930 960

500 2440 1220

In those cases where a second radiograph is considered desirable, it will often

be advantageous to alter the position of the source and film in order that thedefect may be registered from a different angle. This will aid in interpretation of

the defect and also determine its exact location. For this type radiograph, thefocal spot should be displaced a distance of approximately 15 to 20% of thefocal-film distance.

8.4.2 Gamma - Rays

When using Gamma-rays from Iridium (192), Cobalt (60) or other isotopes, therecommended focus-film distance for maximum sensitivity will depend upon thestrength of the gamma-ray source capsule and the thickness of metal being


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radiographed. The following tabulation shows the shortest focus-film distance

which shall be used in radiographing various sections of steel with differentsource strengths:

Source Strength Section Thickness, mm

Ci x g 25 (max) 76 (max) 100 (max) Over 100

25 150 225 380 (1)

100 200 250 430 (1)

250 250 300 510 (1)

500 350 400 580 (1)

(2)

(1) Each application shall be negotiated to determine the source strength and

acceptability standard.

(2) Source strength above 500 Ci x g for any thickness be approved by theCustomer.

8.5 EXP0SURE

All two film radiographic techniques shall consist of two films sandwichedbetween sheets of lead in the following order:

Lead-film-lead-film-lead, except the middle lead can be omitted when using

techniques below 125 kV and for the 1.000.000 volt and up machines, andwhen film of different speeds are used in the radiographic technique.

Single wall thickness radiography shall be used except as otherwise provided

for in this specification.

When radiographing piping or cylindrical shapes, the OD of which is less than90 mm, a technique may be used in which radiation passes through two wallsand both walls are viewed for acceptance on the same film (double-wallviewing). At least four exposures are required around the circumference, thecassette being placed flat against the outside surface of the pipe and the source

located apposite in such a manner that the rays pass through the pipe at an


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angle of not less than 15 degrees to a plane passing through the area being

examined. The quadrant area of the portion being radiographed shall bepositioned nearest the film.

When radiographing piping or cylindrical shapes, the OD of which is 90 mm or

greater, the cassettes should be placed inside the pipe, where practical, in orderthat the rays shall be required to penetrate a single wall thickness of metal. Atleast four exposures should be made in radiographing the full extent of thecircumferential area.

In location where it is impractical to place the cassettes inside the pipe, theoutside of which is 90 mm or greater, the inspection may be conducted as in the

case of pipe which OD is less than 90 mm.

When the diameter of the pipe or cylinder is such that the source of radiationmay be located inside without reducing the focus-film distance below the

requirements of 8.4, the cassettes may be grouped panoramically around theouter surface of the pipe or cylinder. With such an arrangement it may be

possible to radiograph a complete circumferential area with one exposure. It willnormally be necessary to block holes and edges of components being

radiographed in order to prevent halation and undercutting.

8.6 NEGATIVE REQUIREMENTS

Technique shall be such that normal development of negatives shall yield anindividual film density of 1.5 to 4,0, or a double, composite film density of 2 to4.0. Each film of a composite set shall have a minimum density of 1.0.Interpretation shall be made either as single or composite film, whichever is

better suited for interpretation. However, in single film viewing when two filmtechnique is used, if defects is shown it is necessary to view the second filmbefore making a decision regarding the defect. Photographic density may bemeasured by a densitometer or visually comparison step wedge films.

Densitometers shall be calibrated by calibration step wedge films.

Radiographs of welds shall produce negatives with film density through the weldof 2.0 minimum for single viewing and 2.6 minimum for composite viewing.

Each film of a composite set shall have minimum density of 1.3.

Where thickness varies in a section sufficiently to cause difficulty in meetingdensity requirements ( 8.3) and two I.Q.I. must be used, film density minimumshall be 1.3 for single viewing and 2.0 for composite viewing. Each film of acomposite set shall have minimum density of 1.0.

All radiographs shall be free from processing or other film defects which wouldinterfere with proper interpretation of the radiograph. When an apparent defect


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is indicated by a radiograph which, by comparison with the object being

radiographed, is shown conclusively to be entirely on the surface, the area onthe radiograph shall be encircled by the Inspector and identified ad a surface

imperfection by letter S placed immediately adjacent to the encircled area.Take great care to ascertain that such markings are due entirely to surface

markings and not partly due to underlying internal defects. Also, particularlyobserve the area obscured by the I.Q.I. and lead identification markers for thepresence of underlying defects.


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9.0 IDENTIFICATION AND MARKING

9.1 IDENTIFICATION MARKERS

Lead identification markers shall be placed on the section being radiographedso that at least two markers shall be visible on each radiograph to identify theactual length being examined. These markers shall be placed an the sourceside. Whenever identification markers must be placed on the film side, the

technique shall be such that sufficient film overlap is provided to assurecomplete coverage of the full sectional thickness due to angularity. There shall

also be an indication on each film showing the shop order, drawing number anditem of the part being radiographed, Suppliers symbol, and date if spacepermits.

Otherwise, such information shall be supplied with the radiographs.

The letter R shall be marked on all radiographs of repair welds. All I.Q.I. shall

be identified by permanently attached lead numbers at least 2.6 mm high.

9.2 IDENTIFICATION AND MARKING COMPONENTS

The location of identification markers shall be accurately and permanently

stamped, if permission has been obtained in writing from the Purchaser, on themetal surfaces of the component, upon completion of radiography by the

radiograph technician in order that the orientation of the radiograph may beestablished.

These markings shall be maintained on the component throughout thefabrication cycle. In cases where this stamping must be removed as a result ofsubsequent machining, it shall be re-established by the machinist or personremoving same. Every effort shall be made to restore the mark in the exact

location where removed. Also, the radiograph technician shall mark the exact

location of the identification markers on the appropriate drawing and file thedrawing permanently with the films.

When permanent stamping is prohibited or impractical, temporary marking ofthe identification markers shall be made an the metal surfaces of the

component. This type marking shall be maintained until it has been establishedthat the area under examination is satisfactory. In these cases, it is of the

utmost importance that the radiograph technician prepare the marked print veryclearly and accurately as this will be the only medium with which to establish

identity with the part and the radiograph.


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It is very important that work on which radiograph examination has been

performed be shipped with proper identification of the radiograph serial numberand the area stencil numbers intact.


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10.0 RADIOGRAPHIC REPORT

The radiographic technician shall furnish a written report, together with allradiographs for all of the radiographic examinations performed, to thePurchaser. The report shall contain all of the technical data, including the

source size and strength, concerning the radiographic process and techniqueused, together with a sketch or marked up drawing correlating his techniqueincluding an interpretation of each individual gammagraph or radiograph.

The final interpretation of radiographs shall be the responsibility of thePurchaser. Interpretation shall be made by comparison to acceptable standards,

as specified on the manufacturing drawing or specification.


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11.0. QUALITY LEVEL

Requirements for the quality levels from A to C are listed in Table 1.

Quality level A is mandatory for the TF Coil Cases.

Quality level B is applicable when required by Component TechnicalSpecifications.


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12.1 CASTINGS

The acceptability of ferrous and non-ferrous casting examined in accordancewith this specification shall be judged, for X-ray or gamma-ray as specified onthe ordering information, by comparison to the following ASTM Specifications.

E-446 Reference Radiographs for Steel Castings up to 51 mm in Tickness.

E-186 Reference Radiographs for Heavy-Walled (51 to 114 mm) SteelCastings.

E-280 Reference Radiographs for Heavy-Walled (114 to 305 mm) SteelCastings.

12.2 WROUGHT MATERIALS

The acceptability of wrought materials (other than castings) examined inaccordance with this specification shall be agreed upon between the Supplier

and Purchaser.

12.3 WELDMENTS

Unless otherwise specified, the acceptability of all welds, regardless of the

thickness or throat depth of the weld, examined in accordance with therequirements of Quality Level A of Table 1.


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TABLE 1

QUALITY LEVEL A

Material Form Material Thickness Sensitivity Acceptance Criteria

Less than 100 mm 2 1 TWelds

100 mm and greater 1 1 T

Linear, or linearly aligned, flaws arerejectable. Porosity or inclusions greaterthan 1/10 T or 0.8 mm whichever is lessare rejectable

Less than 100 mm 2 1 TCastings


The acceptance Standards of ASTM E-446 Class I shall apply

QUALITY LEVEL B


Less than 100 mm 2 2 TWelds


Indications characterised as crack orincomplete fusion or penetration arerejectable. Other elongated indicationwhich has a length greater than _ T are

rejectable. Porosity or roundedinclusions greater than 1/10 T or 3.0 mm,whichever is less, are rejectable

Less than 100 mm 2 2 TCastings


The acceptance Standards of ASTM E-446 Class II shall apply

QUALITY LEVEL C


Welds All thickness 2 4 T Cracks are rejectable. Lack of fusion or lack of penetration greater than 10% ofthe section thickness are rejectable

Castings All thickness 2 4 T The acceptance Standards of ASTM E-446 Class III shall apply

Note: - T = Material thickness.

- For Quality Level A Type 1 or finer grain film is required.


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ANNEX D

LIQUID PENETRANT EXAMINATION

Ansaldo NDT Specifications 22GRKW v1 0 (1)

Documents

Transcript of Ansaldo NDT Specifications 22GRKW v1 0 (1)