TARGET FLAW SIZES AND ACCEPTANCE FLAW … FLAW SIZES AND ACCEPTANCE FLAW SIZES FOR CANDU FERRITIC...

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Page 1 of 45 TARGET FLAW SIZES AND ACCEPTANCE FLAW SIZES FOR CANDU FERRITIC PIPING Songyan Yang, Ph.D., P.Eng. Senior Design Engineer Engineering Mechanics Department, OPG and Member and Chair COG Piping and Vessel Technical Committee

Transcript of TARGET FLAW SIZES AND ACCEPTANCE FLAW … FLAW SIZES AND ACCEPTANCE FLAW SIZES FOR CANDU FERRITIC...

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TARGET FLAW SIZES AND ACCEPTANCE FLAW SIZES FOR

CANDU FERRITIC PIPING

Songyan Yang, Ph.D., P.Eng.

Senior Design Engineer

Engineering Mechanics Department, OPG

and

Member and Chair

COG Piping and Vessel Technical Committee

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Layout of Presentation

� Target Flaw Size (TFS) and Acceptance Flaw Size (AFS) in performance demonstration of NDE system and disposition of detected flaws

� Current TFS revisit. Rationales, scope and purpose of developing new TFS and AFS

� Development of new TFS and AFS

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Target and Acceptance Flaw Sizes

� Acceptance Flaw Size (AFS)

� An existing flaw if smaller than the AFS, the structural integrity of a pressure boundary component is maintained without repair till next inspection.

� Target Flaw Size (TFS)

� A flaw size used to qualify NDE system. The intent is NDEsystem should detect the flaws ≥ TFS with high confidence.

� Combined Target/Acceptance Flaw Size (TAFS)

� A flaw size used to qualify NDE system and to maintain structural integrity. Flaws ≥ TAFS would be detected with high confidence. Missed indications smaller than TAFSwould not challange the structural integrity of the component.

� New TFS and AFS are combined TAFS

• TFS flaw sizes are smaller than AFS flaw sizes

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Acceptance Flaw Size (AFS)

�To safeguard the structural integrity when flaws are left without repair

small large

Flaw size

AFS for common

components under all

loading conditions;

ASME Section XI IWB-

3500 Tables

AFS for a group of

components under all

loading condition.

New AFS

For common

components

For a specific

component

Continued service without repair,

structural integrity will be maintained

AFS for a specific

component under a

specified and known

loading condition.

Flaw disposition

For a group of

components

sharing similar

characteristics

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Target Flaw Size (TFS) in Piping IS

�To demonstrate performance of NDE process

�Structural integrity is not accounted for all cases.

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Current Target Flaw Size (TFS) for

CANDU ferritic Piping� The TFS was defined in CANDU Ferritic Piping Inspection

Specification (IS) and determined by two Technical Justification documents (TJ)

� COG-JP-4027-V06 R1, Piping IS

� COG-JP-4027-V04, for circumferential flaws

� COG-JP-4027-V12, for tilted and axial flaws

� The TFS is not an acceptance flaw size

� Flaw equal to TFS will not pass ASME acceptance criteria Section XI Table IWB-3514-1. The TFS > Table IWB-3514-1.

� Not all flaws equal to TFS were shown to pass disposition by fracture mechanics analysis per ASME Section XI IWB-3640.

� The TFS is for performance demonstration of NDE system.

� The stability of missed inspection of flaws larger than Table IWB-3514-1 and smaller than the TFS is not demonstrated.

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Current TFS for CANDU Ferritic Piping

–Cont’d� The current TFS was based on postulated flaws with

aspect ratio of 6:1

� The bounding loads were not considered in flaw stability analysis. Representative loads were used instead.

� The subcritical flaw growth was not considered.

� Current TFS by Definition (COG-JP-4027-V06-R1)

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Missing Link 1: Acceptance Flaw Sizes and Current TFS

�IWB-3500 acceptance flaw sizes are too small, or cost is too high, to reliably detect and size by NDE

�Structural integrity of flaws in-between IWB-3500 acceptance flaw sizes and target flaw sizes is not determined

small large

Flaw size

Current piping

target flaw size,

25% tw

Acceptance flaw size by

fracture mechanics

analysis, for example 1Acceptance flaw size by

IWB-3500 tables

X

For example 1, structural

integrity of missed flaw

is not demonstrated

Acceptance flaw size by

fracture mechanics

analysis, for example 2

ok

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Missing Link 2: Flaw Aspect Ratio

�Flaw aspect ratio was arbitrarily set at 6:1 (length:depth) in current piping IS.

�Service induced fatigue cracking tends to be long and shallow.

1. Clearly demonstrated by OPEX

2. Acknowledge by 2010 Edition of Section XI

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Flaw Aspect Ratio: OPEX

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Flaw Aspect Ratio: OPEX

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Flaw Aspect Ratio: Section XI Appendix L

(Operating Plant Fatigue Assessment)

�Flaw aspect ratio of 6:1 was recommended for postulated flaws prior to and including 2007 Code editions

�Flaw aspect ratio other than 6:1 was recommended for piping in 2010 Code edition

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Recommended flaw aspect ratio for ferritic

piping in 2010 Section XI Appendix L

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Requirements for new TFS and AFS

�Both TFS and AFS allow sub-critical crack growth under fatigue. The post-growth TFS and AFScrack sizes are unconditionally stable for all CANDU ferritic piping under all loading conditions (Design and Levels A, B, C and D).

�Sub-critical crack growth happens between two subsequent inspections.

�New TFS (pre-growth) are used for performance demonstration of NDE system.

�New AFS (pre-growth) are to replace Section XI Table IWB-3514-1 as new flaw acceptance criteria to determine continued service.

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Illustration of new TFS and AFS

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Determination of AFS and TFS: Methodology

1. Calculate Critical Flaw Size (CFS) under bounding loading condition and for all credible flaw aspect ratios.

2. Determine AFS from CFS.

3. Perform Fatigue Crack Growth Analysis (FCGA) from AFS to CFS to determine stress cycles.

4. Translate stress cycles to time. Ensure the time is not larger than two consecutive inspections.

5. TFS are determined as the smallest AFS flaw depth with an aspect ratio of 6:1.

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Piping sizes, materials and flaw configuration

�All CANDU ferritic seamless piping, ranging from NPS6 to NPS26 with nominal wall thickness from 11 mm to 85 mm.

�Flaws are located at circumferential fully penetrated butt welds and Heat Affect Zone (HAZ).

�Some weld prep includes counter-boring up to 12.5% of nominal wall thickness.

• Not all counter-bore depths collected in the survey are accommodated. Some counter-bore depths are adjusted to ensure minimum pressure based wall thickness is maintained per ASME Section III NB-3600 Equation (1).

�Flaws are circumferential in the welds or HAZ.

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Piping sizes: Nominal wall thickness

NPS

6

NPS

8

NPS

10

NPS

12

NPS

14

NPS

16

NPS

18

NPS

20

NPS

21

NPS

22

NPS

23

NPS

24

NPS

25

NPS

26

Low thickness 11.0 15.0 18.0 21.0 24.0 26.0 29.0 32.0 32.0 32.0 32.0 38.8 36.0 55.0

High thickness 14.0 19.0 18.0 35.0 28.0 40.0 38.0 46.0 46.0 46.0 70.0 55.0 70.0 85.0

N/A

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

No

min

al

wa

ll t

hic

kn

ess

(m

m)

Range of nominal wall thickness

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Piping sizes: Nominal and local wall thickness

NP

S 6

NP

S 8

NP

S

10

NP

S

12

NP

S

14

NP

S

16

NP

S

18

NP

S

20

NP

S

21

NP

S

22

NP

S

23

NP

S

24

NP

S

25

NP

S

26

Low nominal 11.0 15.0 18.0 21.0 24.0 26.0 29.0 32.0 32.0 32.0 32.0 38.8 36.0 55.0

Low local 10.0 11.0 15.7 18.3 20.0 21.0 25.0 28.0 28.0 28.0 28.0 33.0 31.5 50.5

High nominal 14.0 19.0 35.0 28.0 40.0 38.0 46.0 46.0 46.0 70.0 55.0 70.0 85.0

High local 13.0 15.0 30.6 24.0 35.0 34.0 42.3 41.2 41.1 66.2 50.7 66.5 81.0

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00N

om

ina

l a

nd

lo

cal

wa

ll t

hic

kn

ess

(m

m)

Range of wall thickness (nominal and local)

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Determination of bounding loads

�Pressure and bending moment are considered.

�Pressure is given, including normal operating pressure and emergency pressure

�Bounding bending moment are determined

�Under all loading conditionsLoad Stress limit Source

Design Section III NB-3652

Level B Section III NB-3654.2(a)

Level C Section III NB-3655(a)

Level D Section III NB-3656(a)(2)

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Bounding loads in CFS and AFS

�Level D bounding bending moment plus emergency pressure was used to calculate CFS.

�AFS are assigned 90% of CFS.

�Cyclic loading using in FCGA

• Plus level B bounding bending moment and operating pressure

• Minus level B bounding bending moment and zero pressure

�Stress cycles are determined from FCGA

�Stress cycles are required to be more than those between two consecutive inspections

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Stress cycles and consecutive two inspections

�Stress cycles are determined from FCGA

�Number of station shut-down and re-start cycles between two consecutive inspections is set to 60.

�One stress cycle is assumed to represent one station shut-down and re-start cycle.

�Cycle requirement:

Calculated stress cycles ≥ 60

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Aspect ratios (ARs) of fatigue cracks

�ARs are not fixed in the analysis. ARs are bounded by

• Lower bound: 6

• Upper bound: ASME Section XI (2010) Appendix Table L-3210-1 at ∆σm/∆σg=0.1

�Parametric analyses were on ARs from 6 to the upper bound (11 analyses for evenly distributed between AR=6 to the bounding AR)

�The higher the AR, the lower the CFS and AFSdepth

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Upper bound AR of fatigue cracks

30

35

40

45

50

55

60

65

70

10 30 50 70 90

Fla

w a

spe

ct r

ati

o

Nominal wall thickness (mm)

Upper bound flaw aspect ratio

1. Obtained from ASME Section XI (2010)

Appendix Table L-3210-1 at Δσm/Δσg=0.1.

2. Interpolation is applied

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Description of analysis

�Fracture tolerance analysis to determine CFS

• Elastic Plastic Fracture Mechanics (EPFM) method

• J-integral ductile tearing approach

• Applicable to from brittle to ductile failure mode

�FCGA analysis to determine stress cycles

• Stress Intensity Factor (SIF) based, high cycle fatigue, ASME Section XI Appendix A-4300 (Paris equation)

• Ranges of SIF are checked to ensure validity of method

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Material properties

�Fracture toughness (J-resistance curve)� ASME recommended lower bound at upper-shelf temperature for

carbon steels (Section XI Table C-8321-1) with JIC=105 kJ/m2.

� J-R curve was fitted to power-law J-da formulation

�Tensile properties (Ramberg-Osgood)

• Darlington LBB material testing program, test ID T7,T8,T9

• Sensitivity analysis performed to ensure conservatism

�Tensile properties (Sy and Sm)

• ASME Section II Part D at temperature

�FCGA properties

• ASME Section XI Appendix A-4300 at water environment

2

11

C

R

aCJ

∆⋅= C1 = 189.805 kJ/m2, C2 = 0.258744

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Results: CFS for NPS 12 pipes

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0 10 20 30 40 50 60

Cri

tica

l fla

w d

ep

th (

mm

)

Flaw aspect ratio

NPS 12, tnom=tloc=21.0 mm

NPS 12, tnom= 21.0 mm, tloc=18.38 mm

NPS 12, tnom=tloc= 35.0 mm

NPS 12, tnom=35.0 mm, tloc=30.63 mm

8.61

10.43, 221.78

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14

J-in

teg

ral

(kJ/

m2)

Crack depth (mm)

Critical crack depth

Resistance curve

Crack driving force

at failure

NPS 12", Wall thickness 35.0 mm, without considering Counterbore

Crack aspec t ratio: 6

5.68

6.88, 199.17

0

50

100

150

200

250

300

0 2 4 6 8 10 12

J-in

teg

ral

(kJ/

m2)

Crack depth (mm)

Critical crack depth

Resistance curve

Crack driving force

at failure

NPS 12", Wall thickness 35.0 mm, without considering Counterbore

Crack aspec t ratio: 59.37

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CFS, AFS and Section XI Table IWB-3514-1

0

20

40

60

80

100

120

140

160

180

200

220

240

260

1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5

To

tal

fla

w l

en

gth

(m

m)

Flaw depth (mm)Critical flaw size

Acceptance flaw size

IWB 3514-1 acceptance flaw size

NPS 12", Wall thickness 21.0 mm, without considering Counterbore

0

20

40

60

80

100

120

140

160

1.5 2 2.5 3 3.5 4 4.5 5

To

tal

fla

w l

en

gth

(m

m)

Flaw depth (mm)Critical flaw size

Acceptance flaw size

IWB 3514-1 acceptance flaw size

NPS 12", Wall thickness 21.0 mm, 2.63mm Counterbore

NPS 12, nominal wall thickness is 21 mm

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CFS, AFS and Section XI Table IWB-3514-1

020406080

100120140160180200220240260280300320340360

2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5

To

tal

fla

w l

en

gth

(m

m)

Flaw depth (mm)Critical flaw size

Acceptance flaw size

IWB 3514-1 acceptance flaw size

NPS 12", Wall thickness 35.0 mm, without considering Counterbore

0

20

40

60

80

100

120

140

160

180

200

220

240

2.5 3 3.5 4 4.5 5 5.5

To

tal

fla

w l

en

gth

(m

m)

Flaw depth (mm)Critical flaw size

Acceptance flaw size

IWB 3514-1 acceptance flaw size

NPS 12", Wall thickness 35.0 mm, 4.38mm Counterbore

NPS 12, nominal wall thickness is 35 mm

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CFS results: ductile crack extension and crack driving force (or J-R) at failure

185

190

195

200

205

210

215

220

225

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

6 16 26 36 46 56 66

J-in

teg

ral

an

d J

-R a

t fa

ilu

re (

kJ/

m2)

Du

ctil

e c

rack

de

pth

ex

ten

sio

n (

mm

)

Flaw aspect ratio

duct crack ext (mm)

J-tangent (kJ/m^2)

NPS 12", Wall thickness 35.0 mm, without considering Counterbore

175

180

185

190

195

200

205

210

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

6 16 26 36 46 56 66

J-in

teg

ral

an

d J

-R a

t fa

ilu

re (

kJ/

m2)

Du

ctil

e c

rack

de

pth

ex

ten

sio

n (

mm

)

Flaw aspect ratio

duct crack ext (mm)

J-tangent (kJ/m^2)

NPS 12", Wall thickness 35.0 mm, 4.38mm Counterbore

NPS 12, nominal wall thickness is 35 mm

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FCGA results: NPS 12, tnom = 21 mm

Piping

geometry

Level B

bounding

moment

(N⋅⋅⋅⋅m)

Flaw

aspect

ratio,

CFS as end flaw size AFS as start flaw sizeStress

cyclesdepth

(mm)

length

(mm)

depth

(mm)

length

(mm)

NPS 12

OD: 323.85 mm

tnom: 21.0 mm

tloc:21.0 mm

254172.54

6.00 7.34 44.01 6.60 39.61 96.93

9.88 6.89 68.11 6.20 61.30 93.59

13.76 6.57 90.42 5.91 81.38 91.58

17.64 6.28 110.82 5.65 99.74 90.47

21.52 6.03 129.73 5.43 116.75 89.81

25.40 5.82 147.88 5.24 133.09 89.28

29.28 5.66 165.75 5.10 149.17 88.76

33.16 5.54 183.58 4.98 165.23 88.21

37.04 5.40 200.17 4.86 180.15 87.91

40.92 5.27 215.73 4.75 194.16 87.79

44.80 5.15 230.74 4.64 207.66 87.72

Piping

geometry(N⋅⋅⋅⋅m)

Flaw

aspect

ratio,

CFS as end flaw size AFS as start flaw sizeStress

cycles(mm) (mm) (mm) (mm)

NPS 12

OD: 323.85 mm

tnom: 21.0 mm

tloc:18.38 mm

254172.54

6.00 4.38 26.26 3.94 23.63 84.90

9.88 4.31 42.61 3.88 38.35 82.69

13.76 4.19 57.64 3.77 51.88 81.35

17.64 4.09 72.10 3.68 64.89 80.34

21.52 3.97 85.51 3.58 76.96 79.67

25.40 3.85 97.80 3.47 88.02 79.27

29.28 3.73 109.11 3.35 98.20 79.04

33.16 3.62 120.03 3.26 108.02 78.86

37.04 3.53 130.71 3.18 117.64 78.69

40.92 3.45 141.25 3.11 127.12 78.52

44.80 3.39 151.66 3.05 136.49 78.36

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FCGA results: NPS 12, tnom = 35 mm

Piping

geometry

Level B

bounding

moment

(N⋅⋅⋅⋅m)

Flaw

aspect

ratio,

CFS as end flaw size AFS as start flaw sizeStress

cyclesdepth

(mm)

length

(mm)

depth

(mm)

length

(mm)

NPS 12

OD: 323.85 mm

tnom: 35.0 mm

tloc:35.0 mm

408609.54

6.00 8.61 51.64 7.75 46.48 104.13

11.34 7.86 89.06 7.07 80.15 101.14

16.67 7.24 120.65 6.51 108.59 100.11

22.01 6.78 149.33 6.11 134.40 99.56

27.35 6.47 176.91 5.82 159.22 99.05

32.69 6.21 203.09 5.59 182.78 98.69

38.02 6.06 230.22 5.45 207.19 98.12

43.36 5.94 257.60 5.35 231.84 97.52

48.70 5.83 283.88 5.25 255.49 97.05

54.03 5.75 310.59 5.17 279.53 96.54

59.37 5.68 337.19 5.11 303.47 96.06

Piping

geometry(N⋅⋅⋅⋅m)

Flaw

aspect

ratio,

CFS as end flaw size AFS as start flaw sizeStress

cycles(mm) (mm) (mm) (mm)

NPS 12

OD: 323.85 mm

tnom: 35.0 mm

tloc:30.63 mm

408609.54

6.00 5.16 30.97 4.65 27.87 89.72

11.34 4.85 54.99 4.37 49.49 88.04

16.67 4.54 75.75 4.09 68.18 87.25

22.01 4.34 95.42 3.90 85.88 86.67

27.35 4.19 114.50 3.77 103.05 86.19

32.69 4.08 133.32 3.67 119.99 85.75

38.02 3.97 150.96 3.57 135.86 85.45

43.36 3.87 167.65 3.48 150.89 85.23

48.70 3.76 182.87 3.38 164.58 85.11

54.03 3.65 197.43 3.29 177.68 85.03

59.37 3.58 212.62 3.22 191.35 84.90

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TFS results and Section XI Table IWB-3514-1 (table)

Pipe outer

diameter

Nominal wall

thickness,

(mm)

Local wall

thickness,

(mm)

Target Flaw Size (TFS) Table IWB-3514-1

TFS depth

(mm)

TFS length

(mm)

Aspect ratio

from which

TFS depth is

obtained

TFS depth /

local wall

thickness

Allowable

flaw depth

(mm)

Allowable

flaw depth (%

of local wall

thickness)

NPS 6

168.28 mm

11.00 11.00 3.36 20.16 34.37 30.51% 1.25 11.32%

14.00 14.00 3.54 21.24 37.04 25.26% 1.56 11.11%

NPS 8

219.08 mm

15.00 15.00 3.87 23.22 38.02 25.78% 1.66 11.04%

19.00 19.00 4.05 24.30 42.44 21.34% 2.04 10.75%

NPS 10

273.05 mm18.00 18.00 4.30

25.8041.31 23.91% 1.95 10.82%

NPS 12

323.85

21.00 21.00 4.64 27.84 44.80 22.07% 2.23 10.61%

35.00 35.00 5.11 30.66 59.37 14.6% 3.38 9.67%

NPS 14

355.60 mm

24.00 24.00 4.81 28.86 48.88 20.03% 2.49 10.39%

28.00 28.00 4.82 28.92 55.64 17.21% 2.83 10.11%

NPS 16

406.40 mm

26.00 26.00 5.07 30.42 52.04 19.50% 2.66 10.25%

40.00 40.00 5.41 32.46 61.53 13.51% 3.74 9.36%

NPS 18

457.20 mm

29.00 29.00 5.28 31.68 56.97 18.22% 2.91 10.04%

38.00 38.00 5.45 32.70 60.64 14.35% 3.60 9.72%

NPS 20

508.00 mm

32.00 32.00 5.55 33.30 58.14 17.34% 3.15 9.86%

46.00 46.00 5.78 34.68 64.33 12.57% 4.13 8.99%

NPS 21

533.40 mm

32.00 32.00 5.70 34.20 58.14 17.80% 3.15 9.86%

46.00 46.00 5.83 34.98 64.33 12.68% 4.13 8.99%

NPS 22

558.80 mm

32.00 32.00 5.85 35.10 58.14 18.27% 3.15 9.86%

46.00 46.00 5.89 35.34 64.33 12.80% 4.13 8.99%

NPS 23

584.20 mm

32.00 32.00 6.01 36.06 58.14 18.77% 3.15 9.86%

46.00 46.00 5.95 35.70 64.33 12.94% 4.13 8.99%

59.00 59.00 6.28 37.68 68.49 10.64% 4.82 8.16%

70.00 70.00 6.57 39.42 68.49 9.39% 5.22 7.46%

NPS 24

609.60 mm

38.89 38.89 6.06 36.36 61.03 15.59% 3.67 9.43%

55.00 55.00 6.22 37.32 68.49 11.31% 4.63 8.42%

NPS 25

635.00 mm

36.00 36.00 6.22 37.32 59.79 17.27% 3.46 9.61%

70.00 70.00 6.51 39.06 68.49 9.30% 5.22 7.46%

NPS 26

660.40 mm

55.00 55.00 6.31 37.86 68.49 11.47% 4.63 8.42%

63.00 63.00 6.43 38.58 68.49 10.21% 4.98 7.91%

85.00 85.00 6.96 41.76 68.49 8.18% 5.56 6.55%

TFS depth is the smallest AFSamong all crack AR

TFS length is 6 times of TFSdepth

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TFS results and Section XI Table IWB-3514-1 (plot)

y = 1.762ln(x) - 0.7789

R² = 0.908

y = 2.2958ln(x) - 4.6764

R² = 0.987

0

1

2

3

4

5

6

7

8

10 20 30 40 50 60 70 80

Fla

w d

ep

th (

mm

)

Pipe nominal wall thickness (mm)

Flaw depth vs. wall thickness (no counterbore)

Target Flaw depth (mm)

Allowable flaw depth (mm) from IWB-3514-1

Target flaw depth trendline (logarithmic)

Logarithmic trendline for IWB-3514-1

Target flaw length is six times of target flaw depth

IWB-3514-1 flaw depth is based on largest flaw aspect ratio

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AFS results and Section XI Table IWB-3514-1

�Tabulated AFS are grouped to• Pipe geometry (OD, wall thickness)

• Weld prep (counter-bore depth)

• Flaw aspect ratio

�Tabulated AFS are to replace Table IWB-3514-1 as flaw acceptance standard

Piping geometry

Level D

bounding

moment

(kN⋅⋅⋅⋅m)

Flaw

aspect

ratio,

CFS AFSAFS from Section XI Table

IWB-3514-1

depth

(mm)

length

(mm)

depth

(mm)

depth /

tloc

(%)

length

(mm)

depth /

tloc

(%)

depth

(mm)

length

(mm)

NPS 12

OD: 323.85 mm

tnom: 35.0 mm

tloc:35.0 mm

715.9768

6.00 8.61 51.64 7.75 22.13 46.48 12.91 4.52 27.10

11.34 7.86 89.06 7.07 20.20 80.15 10.87 3.80 43.12

16.67 7.24 120.65 6.51 18.61 108.59 10.39 3.64 60.64

22.01 6.78 149.33 6.11 17.45 134.40 10.11 3.54 77.90

27.35 6.47 176.91 5.82 16.63 159.22 9.94 3.48 95.16

32.69 6.21 203.08 5.59 15.98 182.78 9.89 3.46 113.13

38.02 6.05 230.22 5.45 15.57 207.19 9.82 3.44 130.69

43.36 5.94 257.60 5.35 15.28 231.84 9.77 3.42 148.25

48.70 5.83 283.88 5.25 14.99 255.49 9.73 3.40 165.81

54.03 5.75 310.59 5.17 14.78 279.53 9.70 3.39 183.37

59.37 5.68 337.19 5.11 14.60 303.47 9.67 3.38 200.93

AFS table for NPS 12, tnom=tloc=35 mm

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AFS results and Section XI Table IWB-3514-1

(plot)

y = 2.9153ln(x) - 2.3204

R² = 0.9533

y = 3.1136ln(x) - 6.4338

R² = 0.9898

0

2

4

6

8

10

12

10 20 30 40 50 60 70 80

Fla

w d

ep

th (

mm

)

Pipe nominal wall thickness (mm)

Pipe wall thickness vs. flaw depth (no counterbore,

flaw aspect ratio = 6:1)

Allowable Flaw depth (mm)

Allowable flaw depth (mm) from IWB-3514-1

Allowable flaw depth trendline (logarithmic)

Logarithmic trendline for IWB-3514-1

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ASME Section XI Table IWB-3514-1: 2007 Code edition and 2010 Code edition

� Differences in the two Code editions

• 2010 Code edition simplified the Table by harmonizing pre-service and in-service into one single acceptance standard table

• 2010 Code edition tightens the rule for cracks in small wall thickness with flaw AR of 6 or larger, i.e. smaller allowable flaw sizes

• 2010 Code edition relaxes the rule for cracks in large wall thickness, i.e. larger allowable flaw sizes

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ASME Section XI Table IWB-3514-1: 2007 Code edition

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ASME Section XI Table IWB-3514-1: 2010 Code edition

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ASME Section XI Table IWB-3514-1: Comparison

5

7

9

11

13

15

0 0.1 0.2 0.3 0.4 0.5

All

ow

ab

le F

law

siz

e (

% o

f w

all

th

ick

ne

ss)

Flaw aspect ratio (a/l)

Section XI Allowable planar flaw

t=50 mm (2007 Edition)

t=50 mm (2010 Edition)

a/l=0.1667Area covered

in CANDU Piping IS

Area not covered

in CANDU Piping IS

5

7

9

11

13

15

0 0.1 0.2 0.3 0.4 0.5

All

ow

ab

le F

law

siz

e (

% o

f w

all

th

ick

ne

ss)

Flaw aspect ratio (a/l)

Section XI Allowable planar flaw

t=75 mm (2007 Edition)

t=75 mm (2010 Edition)

a/l=0.1667Area covered

in CANDU Piping IS

Area not covered

in CANDU Piping IS

5

7

9

11

13

15

0 0.1 0.2 0.3 0.4 0.5

All

ow

ab

le F

law

siz

e (

% o

f w

all

th

ick

ne

ss)

Flaw aspect ratio (a/l)

Section XI Allowable planar flaw

t=8 mm (2007 Edition)

t=8 mm (2010 Edition)

a/l=0.1667Area covered

in CANDU Piping IS

Area not covered

in CANDU Piping IS

5

7

9

11

13

15

0 0.1 0.2 0.3 0.4 0.5

All

ow

ab

le F

law

siz

e (

% o

f w

all

th

ick

ne

ss)

Flaw aspect ratio (a/l)

Section XI Allowable planar flaw

t=25 mm (2007 Edition)

t=25 mm (2010 Edition)

a/l=0.1667Area covered

in CANDU Piping IS

Area not covered

in CANDU Piping IS

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Impact of 2010 IWB-3514-1 on the new TFS

y = 1.762ln(x) - 0.7789

R² = 0.908

y = 2.2958ln(x) - 4.6764

R² = 0.987

y = 0.1x + 3E-05

R² = 1

0

1

2

3

4

5

6

7

8

9

10 20 30 40 50 60 70 80

Fla

w d

ep

th (

mm

)

Pipe nominal wall thickness (mm)

Flaw depth vs. wall thickness (no counterbore)

Target Flaw depth

Allowable flaw depth from IWB-3514-1 (2007)

Allowable flaw depth from IWB-3514-1 (2010)

Target flaw depth trendline (logarithmic)

Logarithmic trendline for IWB-3514-1 (2007)

Linear trendline for IWB-3514-1 (2010)

Target flaw length is six times of target flaw depth

IWB-3514-1 flaw depth is based on largest flaw aspect ratio

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Impact of 2010 IWB-3514-1 on the new AFS

y = 2.9153ln(x) - 2.3204

R² = 0.9533

y = 3.1136ln(x) - 6.4338

R² = 0.9898

y = 0.1514x - 0.2854

R² = 0.9998

0

2

4

6

8

10

12

14

10 20 30 40 50 60 70 80

Fla

w d

ep

th (

mm

)

Pipe nominal wall thickness (mm)

Pipe wall thickness vs. flaw depth (no counterbore,

flaw aspect ratio = 6:1)

Allowable Flaw depth

Allowable flaw depth from IWB-3514-1Allowable flaw depth from IWB-3514-1 (2010)

Allowable flaw depth trendline (logarithmic)

Logarithmic trendline for IWB-3514-1

Linear trendline for IWB-3514-1 (2010)

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Impact of 2010 IWB-3514-1 on the new TFS and AFS

� For smaller pipes, or more precisely for pipes with wall thickness less than about 70 mm, the newly proposed TFSand AFS are larger than respective 2010 IWB-3514-1 acceptance flaw sizes. The smaller the wall thickness, the larger the margin.

� For pipe with wall thickness larger than 70 mm, the newly proposed TFS and AFS are smaller than respective 2010 IWB-3514-1 acceptance flaw size.

� For all studied pipe wall thickness, the newly proposed TFS and AFS are larger than respective 2007 IWB-3514-1 acceptance flaw size.

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Recommendation on 2010 IWB-3514-1 on the new TFSand AFS

� For vast majority of CANDU piping covered in the Piping IS that is less than 70 mm in wall thickness, the adoption of the newly proposed TFS and AFS would result in a) less stringent requirements for NDE systems and b) more inspected flaws being accepted for continued service without further flaw analysis.

� For very small number CANDU piping with a wall thickness larger than 70 mm, the newly proposed TFS are large enough for most NDE systems to easily and reliably detect and sizing, it is recommended that

• New TFS be used to qualify NDE system

• 2010 Section XI IWB-3514-1 flaw acceptance standard be used to determine whether a detected flaw is acceptable for continued service.

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Q&A and Discussion