TARGET FLAW SIZES AND ACCEPTANCE FLAW … FLAW SIZES AND ACCEPTANCE FLAW SIZES FOR CANDU FERRITIC...
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
Page 31 of 45
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
Page 32 of 45
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
Page 33 of 45
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
Page 34 of 45
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
Page 35 of 45
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
Page 36 of 45
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
Page 37 of 45
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
Page 38 of 45
ASME Section XI Table IWB-3514-1: 2007 Code edition
Page 39 of 45
ASME Section XI Table IWB-3514-1: 2010 Code edition
Page 40 of 45
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
Page 41 of 45
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
Page 42 of 45
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)
Page 43 of 45
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.
Page 44 of 45
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.
Page 45 of 45
Q&A and Discussion