RT Procedure

PHATECO TECHNICAL SERVICES JOINT STOCK COMPANY

Head Office: 5A/613 Thien Loi str., Vinh Niem wd, Le Chan dist., Hai Phong city, Vietnam Tel: +84 (0) 313 870 870 Fax: +84 (0) 313 313 559 448 Email: [email protected]

Website: www.phateco.com

Project

: Long Phu 1 Thermal Power Plant

Contractor

: AGRIMECO

Location

: Km 10 1A National Road, Thanh Tri District, Ha Noi City, Vietnam

Item

: Circulation Water Piping

No. PTC.LP1.RT.01ASME

Revision No. 0 Date: 18/Aug/2016

Accepted by AGRIMECO

Accepted by Owner

PHATECO

Prepared by

Reviewed by

Approved by

RT Level II

ASNT RT Level III

ACCP RT Level III

NGUYEN QUANG HUY

NGUYEN DUC HIEU

TRAN VAN VUONG

Deputy Manager of Industrial Technical Dept.

Deputy Manager of Quality & Training Dept.

Deputy General Director

RADIOGRAPHIC EXAMINATION PROCEDURE

No.

: PTC.LP1.RT.01ASME

Rev.

:0

Date

: 18-Aug-2016

REVISION RECORD SHEET No

Rev No

1

0

Content of revision First issued

Date of Revision Aug 18th, 2016

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Note: Third column is to be filled in, when the document is being updated/ modified

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CONTENTS 1

INTRODUCTION .................................................................................................................. 4

2

SCOPE .................................................................................................................................... 4

3

APPLICABLE DOCUMENTS .............................................................................................. 4

4

PERSONNEL ......................................................................................................................... 4

5

RADIATION SAFETY .......................................................................................................... 4

6

GENERAL .............................................................................................................................. 4

6.1

RADIATION .......................................................................................................................... 4

6.2

RADIOGRAPHIC FILM ........................................................................................................ 4

6.3

INTENSIFYING SCREEN .................................................................................................... 4

6.4

SCATTERED RADIATION .................................................................................................. 5

6.5

SYSTEM OF IDENTIFICATION.......................................................................................... 5

6.6

RADIOGRAPHIC DENSITY ................................................................................................ 5

6.7

GEOMETRIC UNSHAPNESS .............................................................................................. 6

6.8

FILM PROCESSING.............................................................................................................. 7

6.9

SURFACE PREPARATION .................................................................................................. 8

6.10

VIEWING FACILITIES ......................................................................................................... 8

7

IMAGE QUALITY INDICATOR (IQI) ................................................................................ 8

7.1

IQI MATERIAL ..................................................................................................................... 8

7.2

IQI SELECTION .................................................................................................................... 8

7.3

PLACEMENT OF IQIS........................................................................................................ 10

7.4

NUMBER OF IQIS............................................................................................................... 10

7.5

IQI SENSITIVITY................................................................................................................ 11

8

LOCATION MARKERS ...................................................................................................... 11

8.1

SINGLE-WALL VIEWING ................................................................................................. 12

8.2

DOUBLE-WALL VIEWING ............................................................................................... 13

9

RADIOGRAPHIC TECHNIQUE ........................................................................................ 13

9.1

SINGLE-WALL TECHNIQUE............................................................................................ 13

9.2

DOUBLE-WALL TECHNIQUE.......................................................................................... 13

10

ACCEPTANCE STANDARDS ........................................................................................... 13

10.1

ASME B31.3 ......................................................................................................................... 13

10.2

ASME Section IX, QW-191.1.2.2 ........................................................................................ 16

11

EVALUATION BY PHATECO........................................................................................... 16

12

RADIATION SAFETY ........................................................................................................ 16

13

RECORDS ............................................................................................................................ 17

14

Annex 1 - Rounded Indications Charts Acceptance Standard .............................................. 17

15

Annex 2- ASME Section IX, Maximum acceptable types of rounded indications .............. 24

16

Annex 3 - Radiographic Examination Report Form ............................................................. 25

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RADIOGRAPHIC EXAMINATION PROCEDURE 1

No.

: PTC.LP1.RT.01ASME

Rev.

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INTRODUCTION

This procedure is given to cover the radiographic testing requirements for PHATECO inspectors to perform their works achieving the quality level of services as well as the requirements of Long Phu 1 Extension Thermal Power Plant Project’s Specification. 2

SCOPE

This procedure defines the conditions of performing the radiographic testing for the objects with penetrated thickness up to 62.5 mm. The procedure covers the radiographic examination of materials including castings and welds. 3

APPLICABLE DOCUMENTS

3.1.

ASME Section V, 2015 Edition, Article 2;

3.2.

ASME Section IX, 2015 Edition;

3.3.

ASME B31.3, 2014 Edition;

3.4.

ASNT's Recommended Practice SNT-TC-1A: Personnel Qualifications and Certification in Non-destructive Testing, 2006 and 2011 edition

3.5.

PHATECO's written practice No. PTC.TDD.NDT.P01.

4

PERSONNEL

4.1.

All individual carries out RT examination shall be qualified in accordance with the requirements of PHATECO’s Written Practice based on SNT-TC-1A.

4.2.

Only qualified and certified Level II or Level III personnel shall interpret test results to determine acceptability.

5

RADIATION SAFETY

All radiographic operations shall follow PHATECO’s Radiation Safety Procedure. 6

GENERAL

6.1

RADIATION

6.1.1. Gamma ray sources such as Ir-192 may be used as following table. The radiation energy employed for any radiographic technique shall be achieved the requirements of density and sensitivity in this procedure. 6.1.2. The source size, source to film distance (SFD) and distance from source side of object to the film (OFD) shall be recorded in the report, and the geometric un-sharpness shall meet the requirements of this procedure. 6.1.3. The distance between the source side of the object and the film surface shall be as small as possible. The unsharpness as described of this procedure shall be satisfied. If the film is not close to the object, the thickness of metal penetrated plus the gap thickness shall be taken instead of specimen thickness described in this procedure. 6.2

RADIOGRAPHIC FILM

Radiographs shall be made using industrial radiographic film. Film brand name is Fuji # 50, # 80, #100 or AGFA D7, D5, D4 (ASTM System Class I or II) 6.3

INTENSIFYING SCREEN

Lead intensifying screen shall be used; however fluorescent shall not be permitted. The minimum thickness of the front screen shall be 0.005 in. (0.13 mm) for Ir-192.

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RADIOGRAPHIC EXAMINATION PROCEDURE 6.4

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SCATTERED RADIATION

6.4.1. To reduce back scattered radiation, back lead screen or back lead plate shall be placed in the film holder or behind the film holder during exposure. 6.4.2. As a check on backscattered radiation, a lead symbol "B", with minimum dimensions of ½ in. (13 mm) in height and 1/16 in. (1.5 mm) in thickness, shall be attached to the back of each film holder. 6.4.3. If a light image of the "B”, appears on a darker background of the radiograph, protection from backscatter is insufficient and the radiograph shall be considered unacceptable. A dark image of the "B" on a lighter background is not cause for rejection. 6.5

SYSTEM OF IDENTIFICATION

6.5.1

A system shall be used to produce permanent identification on each radiograph traceable to the contract, component, weld seam, or part numbers, as appropriate. In addition, the organization's symbol and the date of the radiograph shall be plainly and permanently included on the radiograph. In any case, this information shall not obscure the area of interest. The content of identification shall be agreed upon Clie nt’s requirement.

6.5.2

Repair radiographs shall be identified by R1, R2, etc., as applicable.

6.5.3

All radiographs shall be free from mechanical, chemical, or other blemishes to the extent that they do not mask and are not confused with the image of any discontinuity in the interest of the object being radiographed, such blemishes included, but are not limited to; a) Fogging b) Processing defect such as streaks, water marks, or chemical stains c) Scratches, finger marks, crimps, dirtiness, static marks, smudges, or tears d) False indication due to defective screens.

6.6

RADIOGRAPHIC DENSITY

6.6.1

Density Limitation

6.6.1.1 The transmitted film density through the radiographic image adjacent to the designated wire of a wire IQI and the area of interest shall be 1.8 minimum for single film viewing for radiographs made with an X-ray source and 2.0 minimum for radiographs made with a gamma ray source. 6.6.1.2 For composite viewing of multiple film exposures, each film of the composite set shall have a minimum density of 1.3. 6.6.1.3 The maximum density shall be 4.0 for either single or composite viewing. 6.6.2

Density Variation

If the density of the radiograph anywhere through the area of interest varies by more than minus 15% or plus 30% from the densit y through the body of the hold IQI or adjacent to the designated wire of a wire IQI, within the minimum/maximum allowable density ranges specified in this procedure, then an additional IQI shall be used for each exceptional area or areas and the radiograph retaken. When calculating the allowable variation in density, the calculation shall be rounded to the nearest 0.1 within the range specified in this procedure. 6.6.3

Densitometer and Step Wedge Comparison Films

6.6.3.1 Densitometers. Densitometers shall be calibrated at least every 90 days during use as follows:

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(a)

A national standard step tablet or a step wedge calibration film, traceable to a national standard step tablet and having at least 5 steps with neutral densities from at least 1.0 through 4.0, shall be used. The step wedge calibration film shall be verified within the last year by comparison with a national standard step tablet unless, prior to first use, it was maintained in an original light-tight and waterproof sealed package as supplied by the Film Manufacturer. Step wedge calibration films may be used without verification for one year upon opening, provided it is within the Manufacturer stated shelf life.

(b)

The densitometer manufacturer step-by-step instructions for the operation of the densitometer shall be followed.

(c)

The density steps closest to 1.0, 2.0, 3.0, and 4.0 on the national standard step tablet or step wedge calibration film shall be read.

(d)

The densitometer is acceptable if the density readings do not vary by more than ±0.05 density units from the actual density stated on the national standard step tablet or step wedge calibration film.

6.6.3.2 Step Wedge Comparison Films Step wedge comparison films shall be verified prior to first use, unless performed by the film manufacturer, as follows: (a)

The density of the steps on a step wedge comparison film shall be verified by a calibrated densitometer.

(b)

The step wedge comparison film is acceptable if the density readings do not vary by more than ±0.1 density units from the density stated on the step wedge comparison film.

6.6.3.3 Periodic Verification (a)

Densitometers. Periodic calibration verification checks shall be performed as described above paragraph at the beginning of each shift, after 8 hour of continuous use, or after change of apertures, whichever comes first.

(b)

Step Wedge comparison Films. Verification checks shall be performed annually per above paragraph.

6.7

GEOMETRIC UNSHAPNESS

6.7.1

The geometric unsharpness of the radiographic shall not exceed the following values:

6.7.2

Material thickness, mm

Ug, Maximum, mm

Under 50.8

0.51

50.8 through 76.2

0.76

Over 76.2 through 101.6

1.02

Greater than 101.6

1.78

Geometric unsharpness of the radiograph shall be determined in accordance with below formula: Ug = Fd/D

Where, Ug =

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F = source size, the maximum projected dimension of the radiating source (or effective focal spot) in the plane perpendicular to the distance D from the weld or object being radiographed, mm. D =

distance from source of radiation to weld or object being radiographed, mm.

d =

distance from source side of weld or object being radiographed to the film

6.8

FILM PROCESSING

6.8.1

Development

Normal development is 5 to 8 min in 20 0C. Longer development time generally yields faster film speed and slightly more contrast. The chemical manufacturer’s recommendation should be followed in choosing a development time. When the temperature is higher or lower, development time must be changed. Again, consult’s chemical manufacturer – recommended development time versus temperature charts. Other recommendations of the chemical manufacturer to be followed are replenishment rates, renewal of solutions, and other specific instructions. 6.8.2

Agitation

Shake the film horizontally and vertically, ideally for a few seconds each minute during development. This will help film develop evenly. 6.8.3

Stop Bath or Rinse

After development is complete, the activity of developer remaining in the emulsion should be neutralized by an acid stop bate or, if this is not possible, by rinsing with vigorous agitation in clear water. Follow the film manufacturer's recommendation of stop bath composition. (Or length of alternative rinse), time i mmersed, and life of bath. 6.8.4

Fixing

The films must not touch one another in the fixer. Agitate the hangers vertically for about 10s and again at the end of the first minute, to ensure uniform and rapid fixation. Keep them in the fixer until fixation is complete (that is, at least twice the clearing time), but not more than 15 min in relatively fresh fixer. Frequent agitation wil l shorten the time of fixation. 6.8.5

Fixer Neutralizing

The use of a hypo eliminator or fixer neutralizer between fixation and washing may be advantageous. These materials permit a reduction of both time and amount of water necessary for adequate washing. The recommendations of the manufacturer’s as to preparation, use, and useful life of the baths shall be observed rigorously. 6.8.6

Washing

The washing efficiency is a function of wash water, its temperature, and flow, and the film being washed. Generally, washing is very slow below 16oC. When washing at temperatures above 30oC, care should be exercised not to leave films in the water too long. The films should be washed in batches without contamination from new film brought over from the fixer. If pressed for capacity, as more films are put in the wash, partially washed film should be moved in the direction of the inlet. -

6.8.7

The cascade method of washing uses less water and gives better washing for the same length of time. Divide the wash tank into two sections (may be two tanks). Put the films from the fixer in the outlet section. After partial washing, move the batch of film to the inlet section. This completes the wash in fresh water. For specific washing recommendations, consult the film manufacturer.

Wetting Agent

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Dip the film for approximately 30's in a wetting agent. This makes water drain evenly off film, which facilitates quick, even drying. 6.8.8

Drying

Drying is a function of film (base and emulsion); processing (hardness of emulsion after washing, use of wetting agent); and drying air (temperature, humidity, flow). Manual drying can vary from still air drying at ambient temperature to as high as 60°C with air circulated by a fan. Film manufacturers should again be contacted for recommended drying conditions. Take precaution to tighten film on hangers, so that it cannot touch in the dryer. Too hot a drying temperature at low humidity can result in uneven drying and should be avoided. 6.9

SURFACE PREPARATION

6.9.1

Materials Including Castings Surfaces shall satisfy the requirements of the applicable materials specification or referencing Code Section, with additional conditioning, if necessary, by any suitable process to such a degree that the resulting radiographic image due to any surface irregularities cannot mask or be confused with the image of any discontinuity.

6.9.2

Welds The weld ripples or weld surface irregularities on both the inside (where accessible) and outside shall be removed by any suitable process to such a degree that the resulting radiographic image due to any surface irregularities cannot mask or be confused with the image of any discontinuity. The finished surface of all butt-welded joints shall be flush with the base material or shall have reasonably uniform crowns, with reinforcement not to exceed that specified in the referencing Code Section.

6.10

VIEWING FACILITIES

Viewing facilities shall provide subdued background lighting of an intensity that will not cause troublesome reflections, shadows, or glare on the radiograph. Equipment used to view radiographs for interpretation shall provide a variable light source sufficient for the designated wire to be visible for the specified density range. The viewing conditions shall be such that light from around the outer edge for the radiograph or coming through lowdensity portions of the radiograph does not interfere with interpretation. 7

IMAGE QUALITY INDICATOR (IQI)

7.1

IQI MATERIAL

IQIs shall be selected from either the same alloy material group or grade as identified in SE747 or from an alloy material group or grade with less radiation absorption than the material being radiographed. 7.2

IQI SELECTION

7.2.1

The designated wire diameter shall be as specified in Table 1. The alternative wire IQI essential wire diameter is equal to or less than the required standard IQI essential wire in Table 1.

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TABLE 1 - IQI SELECTION Wire type IQI

Nominal Single-Wall

SOURCE SIDE

Material Thickness

Wire IQI set Essential

Range (mm)

FILM SIDE

Wire Dia. Wire (mm) Essential

IQI set

Wire Dia. (mm)

Up to 6.4 Incl.

5

1A

0.20

4

1A

0.16

Over 6.4 Through 9.5

6

1A, 1B

0.25

5

1A

0.20


7

1B

0.33

6

1A, 1B

0.25


8

1B

0.41

7

1B

0.33


9

1B

0.51

8

1B

0.41


10

1B

0.64

9

1B

0.51


11

1B, 1C

0.81

10

1B

0.64


12

1C

1.02

11

1B, 1C

0.81


13

1C

1.27

12

1C

1.02

Over 101.6Through 152.4

14

1C

1.60

13

1C

1.27


16

1C, 1D

2.54

14

1C

1.60


17

1D

3.20

16

1C, 1D

2.54


18

1D

4.06

17

1D

3.20


20

1D

6.35

18

1D

4.06


21

1D

8.13

20

1D

6.35

7.2.2

If there is not any special requirement, wire type IQI, in accordance with Table 3, shall be used.

7.2.3

Welds with Reinforcements The thickness on which the IQI is based is the nominal single wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the referencing code section as flowing table 3. Backing rings or strips shall not be considered as part of the thickness in IQI selection. The actual measurement of the weld reinforcement is not required. Table 3: Weld reinforcement Height (ASME B31.3, Table 341.3.2) Weld Thickness, Tw Weld reinforcement mm Height, mm

6.2.4

Tw ≤ 6

1.5

6 < Tw ≤ 13

3

13 < Tw ≤ 25

4

Tw > 25

5

Welds without Reinforcements The thickness on which IQI is based is the nominal single wall thickness. Backing rings or strips shall not be considered as part of the weld thickness in IQI selection. Page 9 of 25


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Table 2- WIRE IQI DESIGNATION, WIRE DIAMETER, AND WIRE IDENTIFY

Set A Wire diameter

Set B Wire

Wire Diameter,

Wire

In.

(mm)

Identify

In.

(mm)

Identify

0.0032

(0.08)

1

0.010

(0.25)

6

0.004

(0.10)

2

0.013

(0.33)

7

0.005

(0.13)

3

0.016

(0.41)

8

0.0063

(0.16)

4

0.020

(0.51)

9

0.008

(0.20)

5

0.025

(0.64)

10

0.010

(0.25)

6

0.032

(0.81)

11

Set C Wire diameter

Set D Wire

Wire Diameter,

Wire

In.

(mm)

Identify

In.

(mm)

Identify

0.032

(0.81)

11

0.100

(2.54)

16

0.040

(1.02)

12

0.126

(3.20)

17

0.050

(1.27)

13

0.160

(4.06)

18

0.063

(1.60)

14

0.200

(5.08)

19

0.080

(2.03)

15

0.250

(6.35)

20

0.100

(2.54)

16

0.320

(8.13)

21

7.3

PLACEMENT OF IQIS

7.3.1

Source Side IQIs The IQIs shall be placed on the source side of the part being examined, except in the condition described as below.

7.3.2

Film Side IQIs Where inaccessibility prevents hand placing the IQIs on the source side, it shall be placed on the film side in contact with the part being examined. A lead letter "F" at least as high as the IQI identification number(s) shall be placed adjacent to or on the IQIs.

7.3.3

IQI Placement for Welds - Wire IQIs The IQIs shall be placed on the weld so that the length of the wires is perpendicular to the length of the weld. The identification numbers and, when used, the lead letter “F”, shall not be in the area of interest, except when geometric configuration makes it impractical.

7.3.4

IQI Placement for Materials Other Than Welds The IQIs with the IQI identification number(s), and, when used, the lead letter "F", may be placed in the area of interest.

7.4

NUMBER OF IQIS

When one or more film holders are used for an exposure, at least one IQI image shall appear on each radiograph except as outlined below. 7.4.1

Multiple IQIs

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If the requirements of paragraph 7.6 are met by using more than one IQI, one shall be representative of the lightest area of interest and the other the darkest area of interest; the intervening densities on the radiograph shall be considered as having accept able density. 7.4.2

Special Case

7.4.2.1 For cylindrical components where the source is placed on the axis of the object and one or more film holders are used for a single exposure of a complete circumference, at least three IQIs shall be spaced approximately 120deg. apart. Where sections of longitudinal welds are required under the following conditions: a. When the complete circumference is radiographed using one or more film holders, or; b. When a section or sections of the circumference, where the length between the ends of the outermost sections span 240 or more deg., is radiographed using one or more film holders. Additional film locations may be required to obtain necessary IQI spacing. 7.4.2.2 For cylindrical components where the source is placed on the axis of the component for a single exposure, at least three IQIs, with one placed at each end of span of the circumference radiographed and one in the approximate center of the span, are required under the following conditions: c. When a section of a circumference, the length of which is greater than 120deg. And less than 240deg. is radiographed using just one film holder, or; d. When a section or sections of the circumference, where the length between the ends of the outermost sections span less than 240deg., is radiographed using more than one film holder. 7.4.2.3 In 7.4.2.1 and 7.4.2.2 above, where sections of longitudinal welds adjoining the circumferential weld are radiographed simultaneously with the circumferential weld, an additional IQI shall be placed on each longitudinal weld at the end of section most remote from the junction with the circumferential weld being radiographed. 7.4.2.4 For segments of a flat or a curved (i.e., ellipsoidal, torispherical, toriconical, elliptical, etc.) component where the source is placed perpendicular to the center of a length of weld for a single exposure when using more than three film holders, at least three IQIs, one placed at each end of the radiographed span and one in the approximate center of the span, are required. 7.4.2.5 When an array of components in a circle is radiographed, at least one IQI shall show on each component image. 7.4.2.6 In order to maintain the continuity of records involving subsequent exposures, all radiographs exhibiting IQIs which qualify the techniques permitted in accordance with 6.4.2.1 through 6.4.2.4 above shall be retained. 7.5

IQI SENSITIVITY

Radiography shall be performed with a technique of sufficient sensitivity to display the essential wire of a wire IQI as show in this procedure. The radiographs shall also display the IQI identifying numbers and letters. If the essential wire, do not show on any film in a multiple film technique, but do show in composite film viewing, interpretation shall be permitted only by composite film viewing. 8

LOCATION MARKERS

Location markers (see Figure-1 below), which are to appear as radiographic images on the film, shall be placed on the part, not on the exposure holder/cassette. Their locations shall be permanently marked on the surface of the part being radiographed when permitted, or on Page 11 of 25


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a map, in a manner permitting the area of interest on a radiograph to be accurately traceable to its location on the part, for the required retention period of the radiograph. Evidence shall also be provided on the radiograph that the required coverage of the region being examined has been obtained. Location markers shall be placed as follows. 8.1

SINGLE-WALL VIEWING

8.1.1

Source Side Markers

Source side location markers shall be used when radiographing the following: (1) Flat components or longitudinal joints in cylindrical or conical components; (2) Curved or spherical components whose concave side is toward the source and when the "source-to-material" distance is less than the inside radius of the component; (3) Curved or spherical components whose convex side is toward the source. 8.1.2

Film Side Markers

(1) Film side location markers shall be used when radiographing either curved or spherical components whose concave side is toward the source and when the "source-to-material" distance is greater than the inside radius. (2) As an alternative for source side markers, film side markers may be used when the radiograph shows coverage beyond the location markers to the extent demonstrated by Figure-1 (e) and when this alternate is documented in the record.

Figure 1 – Location Marker Sketches 8.1.3

Either Side Markers

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Either source side or film side location markers may be used when radiographing either curved or spherical components whose concave side is toward the source and the "sourceto-material" distance equals the inside radius of the component. 8.2

DOUBLE-WALL VIEWING

At least one location marker shall be placed on the outside surface adjacent to the weld (or on the material in the area of interest) for each radiograph. 9

RADIOGRAPHIC TECHNIQUE

A single-wall exposure technique shall be used for radiography whenever practical. When it is not practical to use a single-wall technique, a double-wall technique shall be used. An adequate number of exposures shall be made to demonstrate that the required coverage has been obtained 9.1

SINGLE-WALL TECHNIQUE

In the single-wall technique, the radiation passes through only one wall of the weld (material), which is viewed for acceptance on the radiograph. 9.2

DOUBLE-WALL TECHNIQUE

When it is not practical to use a single-wall technique, one of the following double-wall techniques shall be used. 9.2.1

Single-Wall Viewing For materials and for welds in components, a technique may be used in which the radiation passes through two walls and only the weld (material) on the film side wall is viewed for acceptance on the radiograph. When complete coverage is required for circumferential welds (materials), a minimum of three exposures taken 120 deg. to each other shall be made.

9.2.2

Double-Wall Viewing For materials and for welds in components 3½ in.(89mm) or less in nominal outside diameter, a technique may be used in which the radiation passes through two walls and the weld (material) in both walls is viewed for acceptance on the same radiograph. For doublewall viewing, only a source side IQI shall be used. Care shall be exercised to ensure that the required geometric un-sharpness is not exceeded. If the geometric un-sharpness requirement cannot be met, then single-wall viewing shall be used. (1) For welds, the radiation beam may be offset from the plane of the weld at an angle sufficient to separate the images of the source side and film side portions of the weld so that there is no overlap of the areas to be interpreted. When complete coverage is required, a minimum of two exposures taken 90deg. to each other shall be made for each joint. (2) As an alternative, the weld may be radiographed with the radiation beam positioned so that the images of both walls are superimposed. When complete coverage is required, a minimum of three exposures taken at either 60deg. or 120deg. to each other shall be made for each joint. (3) Additional exposures shall be made if the required radiographic coverage cannot be obtained using the minimum number of exposures indicated in (a) or (b) above.

10

ACCEPTANCE STANDARDS

10.1

ASME B31.3

Acceptance Criteria refer to ASME B31.3, Table 341.3.2 Acceptance criteria for welds and examination methods for evaluating weld imperfections. Page 13 of 25


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Criteria (A to M) for Types of Welds and for Service Conditions [Note (1)] Normal and Category M Fluid Service Type of Weld

Severe Cyclic Conditions

Category D Fluid Service

Type of Weld

Type of Weld

] ) 3 ( e t o N [ e v o o r G l a n i d u t i g n o L

h c n a r ] ) 2 B ] ) & ( e 4 t ( e o e v N t o [ o o r n N [ G i o t t r e e c l l i e i t F M n n o , C h t r i G


] ) 4 ( e t o N [ t e l l i F

A

A

A

A

A

A

A

A

A

B

A

N/A

E

E

N/A

h c n a r B ) 2 e & t e o n v ( o n o r i o g t r e c e t i n n M o , c h t r i G

e v o o r G r e t i M , h t r i G


] ) 4 ( e t o N [ t e l l i F

] ) 2 ( e t o N [ n o i t c e n n o C h c n a r B

A

A

A

A

A

Crack

A

A

C

A

N/A

A

Lack of fusion

A

A

N/A

C

A

N/A

B

Incomplete penetration

D

D

N/A

N/A

N/A

N/A

N/A

Round indication Internal slag inclusion, tungsten inclusion, or elongated indication

Weld Imperfections

G

G

N/A

F

F

N/A

N/A

N/A

N/A

N/A

H

A

H

A

A

A

I

A

H

H

Undercutting

K

K

N/A

K

K

N/A

K

K

N/A

K

Concave surface

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Criterion Sym -bol

Measurement

Acceptable Value limits (Note 5)

A

Extent of imperfection

Zero (no evident imperfection)

B

Cumulative length of Incomplete penetration

≤ 38 mm in any 150 mm weld length or 25% of total weld length, whichever is less

C

Cumulative length of lack of fusion and incomplete ≤ 38mm (1.5in.) in any 150mm weld length penetration or 25% of total weld length, whichever is less

D

Size and distribution of round indication

See BPV Code, Section VIII, Division l. Appendix 4 (see Annex I in this procedure)

E

Size and distribution of round indication

For Tw ≤ 6mm, limit is same as D For Tw > 6mm, limit is 1.5 x D

F

G

H

Slag inclusion, tungsten inclusion, or elongated indication Individual length

≤ Tw/3

Individual width

≤ 2.5mm and ≤ Tw/2

Cumulative length

≤ Tw in any 12Tw weld length

Slag inclusion, tungsten inclusion, or elongated indication Individual length

≤ 2Tw

Individual width

≤ 3 mm and ≤Tw/2

Cumulative length

≤ 4Tw in any 150mm weld length

Depth of undercut

≤ 1 mm and ≤ Tw/4

Depth of undercut

≤ 1.5 mm and ≤ (Tw/4 or 1mm)

Depth of surface concavity

Total joint thickness, incl. weld reinf., ≥ Tw

(*)

I (*)

K (**)

N/A

None Application

Notes: (1) Criteria given are for required examination. More stringent criteria may be specified in the engineering design. (2) Branch connection weld includes pressure containing welds in branches and fabricated laps (3) Longitudinal groove weld includes straight and spiral seam. (4) Fillet weld includes socket and seal welds, and attachment welds for slip-on flanges, branch reinforcement, and supports.

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(5) Where two limiting values are separated by "and," the lesser of the values determines acceptance. Where two sets of values is separated by "or," the larger value is acceptable. Tw is the nominal wall thickness of the thinner of two components joined by a butt weld. (*) Undercuts shall be inspected by visual examination, if appeared on the radiograph it shall be checked against visual examination result for the final acceptance. (**) When surface concavity appears on radiograph with the density more than the density on base metal, it shall be rejected. Otherwise it will be accepted.

10.2

ASME Section IX, QW-191.1.2.2

Welder and welding operator performance tests by radiography of welds in test assemblies shall be judged unacceptable when the radiograph exhibits any imperfections in excess of the limits specified below (a)

Linear Indications (1) any type of crack or zone of incomplete fusion or penetr ation (2) any elongated slag inclusion which has a length greater than (-a) 1/8 in. (3 mm) for t up to 3 /8 in. (10 mm), inclusive (-b) 1/3t for t over 3/8 in. (10 mm) to 2 ¼ in. (57 mm), inclusive (-c) ¾ in. (19 mm) for t over 2 ¼ in. (57 mm) (3) any group of slag inclusions in line that have an aggregate length greater than t in a length of 12t , except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfec tion in the group (b) Rounded Indications (1) The maximum permissible dimension for rounded indications shall be 20% of t or 1/8 in. (3 mm), whichever is smaller. (2) For welds in material less than 1/ 8 in. (3 mm) in thickness, the maximum number of acceptable rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionately fewer number of rounded indications shall be permitted in welds less than 6 in. (150 mm) in length. (3) For welds in material 1/ 8 in. (3 mm) or greater in thickness, the charts in ASME Section IX Figure QW-191.1.2.2(b)(4) (see Annex 2 in this procedure) represent the maximum acceptable types of rounded indications illustrated in typically clustered, assorted, and randomly dispersed configurations. Rounded indications less than 1/32 in. (0.8 mm) in maximum diameter shall not be considered in the radiographic acceptance tests of welders and welding operators in these ranges of material thicknesses.

11

EVALUATION BY PHATECO

The PHATECO shall be responsible for the review, interpretation, evaluation, and acceptance of the completed radiographs to assure compliance with the requirements of Article 2, ASME Section V and the referencing Code Section. The radiographic technique details and the radiograph review form documentation shall accompany the radiographs. Acceptance shall be completed prior to presentation of the radiographs and accompanying documentation to the Inspector. 12

RADIATION SAFETY

All radiographic work carried out by PHATECO personnel will conform to PHATECO safety procedure and local statutory safety equipment. PHATECO Safety Officer will conduct periodic safety inspection at all work locations and will have the authority to Page 16 of 25


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suspend work if not satisfied with safety procedures adopted. Personnel found not adhering to the standard safety procedures may be subjected to disciplinary action. 13

RECORDS

13.1

The results shall be recorded in the attached form by the certified personnel who perform the radiographic examination. Radiographic examination records including radiographic films shall be handover to the Manufacturer and Manufacturer shall retain as requirement in Manufacturer’s manual.

13.2

The PHATECO shall prepare and document the radiographic technique details. As a minimum, the following information shall be provided. (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12)

14

Identification Dimensional map (if used) of marker placement Number of radiographs (exposures) X-ray voltage or isotope type used Source size Base material type and thickness, weld thickness, weld reinforcement thickness, as applicable Source-to-object distance Distance from source side of object to film Film manufacturer and their assigned type/ designation Number of film in each film holder/cassette Single- or double-wall exposure Single-or double-wall viewing

Annex 1 - Rounded Indications Charts Acceptance Standard

(1) Applicability of These Standards These standards are applicable to ferritic, austenitic, and nonferrous materials. (2) Terminology (a) Rounded Indications. Indications with a maximum length of three times the width or less on the radiograph are defined as rounded indications. These indications may be circular, elliptical, conical, or irregular in shape and may have tails. When evaluating the size of an indication, the tail shall be included. The indication may be from any imperfection in the weld, such as porosity, slag, or tungsten. (b) Aligned Indications. A sequence of four or more rounded indications shall be considered to be aligned when they touch a line parallel to the length of the weld drawn through the center of the two outer rounded indications. (c) Thickness t . t is the thickness of the weld, excluding any allowable reinforcement. For a butt weld joining two members having different t hickness at the weld, t is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in t. (3) Acceptance Criteria (a) Image Density. Density within the image of the indication may vary and is not a criterion for acceptance or rejection. (b) Relevant Indications. Only those round indications which exceed the following dimensions shall be considered relevant.

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RADIOGRAPHIC EXAMINATION PROCEDURE -

1/10 t for t less than 3 mm

-

0.4 mm for t equal to 3 mm to 6 mm, incl.

-

0.8 mm for t greater than 6 mm to 50 mm, incl

-

1.6 mm for t greater than 50 mm

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(c) Maximum Size of Rounded Indication. (See table 4.1 for example) The maximum permissible size of any indication shall be 1/4t , or 4 mm, whichever is smaller; except that an isolated indication separated from an adjacent indication by 25 mm or more may be 1/3t, or 6 mm, whichever is less. For t greater than 50 mm, the maximum permissible size of an isolated indication shall be increased to 10 mm.

Table 4.1 Maximum Size of Acceptable Rounded Indication

(d) Aligned Rounded Indications. Aligned rounded indications are acceptable when the summation of the diameters of the indications is less than t in a length of 12t . The length of groups of aligned rounded indications and the spacing between the groups shall meet the requirements of following Figure. (e) Spacing The distance between adjacent rounded indications is not a factor in determining acceptance or rejection, except as required for isolated indications or groups of aligned indications. (f) Rounded Indication Charts. The rounded indications characterized as imperfections shall not exceed that shown in the charts. The following charts illustrate various types of assorted, randomly

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dispersed and clustered rounded indications for different weld thicknesses greater than 3 mm. These charts represent the maximum acceptable concentration limits for rounded indications. The charts for each thickness range represent full scale 150 mm radiographs, and shall not be enlarged or reduced. The distributions shown are not necessarily the patterns that may appear on the radiograph, but are typical of the concentration and size of indications permitted. (g) Weld Thickness t less than 3 mm For t less than 3 mm, the maximum number of rounded indications shall not exceed 12 in a 150 mm length of weld. A proportionally fewer number of indications shall be permitted in welds less than 150 mm in length. (h) Clustered Indications. The illustrations for clustered indications show up to four times as many indications in a local area, as that shown in the illustrations for random indications. The length of an acceptable cluster shall not exceed the lesser of 25 mm or 2t . Where more than one cluster is present, the sum of the lengths of the clusters shall not exceed 25 mm in a 150 mm length weld.

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Annex 2- ASME Section IX, Maximum acceptable types of rounded indications

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Annex 3 - Radiographic Examination Report Form

AGRIMECO

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RT Procedure

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