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Pipeline Research Council International,
Inc.
Advances in Pipeline Fitness-for-Service
A PRCI Webinar
SEIKOWAVE
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We will cover
A brief review of corrosion damage assessment methods
Determination of burst pressure – two examples
Integration with NDT tools
3D surface measurements
UT
What’s next?
Pit gage data entry interface
ASME B31G (2012), DNV RP-F101, Kastner
Q&A
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A BRIEF HISTORY OF CORROSION
DAMAGE ASSESSMENT METHODS FOR
PIPELINES
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Barlow’s Formula
Barlow's formula calculated the
maximum internal pressure that a pipe
can withstand using the dimensions
and material properties of the pipe
𝑃 =𝜎𝑜2𝑡
𝐷 Where
P = burst pressure
so = allowable stress
t = pipe wall thickness
D = outside diameter of the pipe
t
D
D
direction of flow
t
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Maxey’s Surface Flaw Equation
Developed in the 1960’s to describe the impact of flaws on reducing the maximum pressure of a pipe; modifies the stress based on the surface flaw geometry
𝜎 = 𝜎𝑜
1 −𝐴𝐴𝑜
1 −𝐴
𝐴𝑜𝑀 Where
𝐴 = 𝐿𝑑
𝑑 = 𝑑𝑒𝑝𝑡ℎ 𝑜𝑓 𝑎 𝑟𝑒𝑐𝑡𝑎𝑛𝑔𝑢𝑙𝑎𝑟 𝑑𝑒𝑓𝑒𝑐𝑡
𝐴𝑜 = 𝐿𝑡
𝑀 = 1 +0.8𝐿2
𝐷𝑡
t
D
D
direction of flow
t
d
L
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Corrosion Assessment Failure Prediction
Based on concepts pioneered by Maxey and Kiefner
Modifications to Barlow’s formula to account for surface flaws
First ASME B31G standard in 1991
Subsequent revisions in 2009, and 2012
RSTRENG
Based on a more detailed assessment of the shape of the corrosion damage
Incorporates more accurate Folias factors
Original development by John F. Kiefner while at Battelle Memorial Institute
Ongoing development and advancement supported by PRCI
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Original B31G
𝑃𝑏𝑢𝑟𝑠𝑡 =𝜎𝑓𝑙𝑜𝑤2𝑡
𝐷
1 −2𝑑3𝑡
1 −2𝑑3𝑡𝑀
Where
𝐴 =2
3𝑑𝐿
𝜎𝑓𝑙𝑜𝑤 = 1.1𝑆𝑀𝑌𝑆
𝑀 = 1 +0.8𝐿2
𝐷𝑡L = defect lengthd = maximum defect depthD = pipe diametert = pipe wall thicknessSMYS = Specified Minimum Yield Strength
For defects defined as 𝐿 ≤ 20𝐷𝑡
t
D
D
direction of flow
t
d
L
Parabolic defect model for defects
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Original B31G
𝑃𝑏𝑢𝑟𝑠𝑡 =𝜎𝑓𝑙𝑜𝑤2𝑡
𝐷1 −
𝑑
𝑡Where
𝐴 = 𝐿𝑑
𝜎𝑓𝑙𝑜𝑤 = 1.1𝑆𝑀𝑌𝑆
L = defect length
d = maximum defect depth
D = pipe diameter
t = pipe wall thickness
SMYS = Specified Minimum Yield Strength
For defects defined as 𝐿 > 20𝐷𝑡
t
D
D
direction of flow
t
d
L
Rectangular defect model for long defects
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0.85dL Method
𝑃𝑏𝑢𝑟𝑠𝑡 =𝜎𝑓𝑙𝑜𝑤2𝑡
𝐷
1 − 0.85𝑑𝑡
1 − 0.85𝑑𝑡𝑀
Where
𝐴 = 0.85𝑑𝐿
𝜎𝑓𝑙𝑜𝑤 = 𝑆𝑀𝑌𝑆 + 10,000𝑝𝑠𝑖
𝑀 = 1 + 0.6275𝐿2
𝐷𝑡− 0.003375
𝐿2
𝐷𝑡
2
L = defect lengthd = maximum defect depthD = pipe diametert = pipe wall thicknessSMYS = Specified Minimum Yield Strength
For defects defined as 𝐿 ≤ 50𝐷𝑡
t
D
D
direction of flow
t
d
L
Bulging stress magnification factor
(Folias factor) depends on defect length
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0.85dL Method
𝑃𝑏𝑢𝑟𝑠𝑡 =𝜎𝑓𝑙𝑜𝑤2𝑡
𝐷
1 − 0.85𝑑𝑡
1 − 0.85𝑑𝑡𝑀
Where
𝐴 = 0.85𝑑𝐿
𝜎𝑓𝑙𝑜𝑤 = 𝑆𝑀𝑌𝑆 + 10,000𝑝𝑠𝑖
𝑀 = 0.032𝐿2
𝐷𝑡+ 3.3
L = defect lengthd = maximum defect depthD = pipe diametert = pipe wall thicknessSMYS = Specified Minimum Yield StrengthFor defects defined as 𝐿 > 50𝐷𝑡
t
D
D
direction of flow
t
d
L
Bulging stress magnification factor
(Folias factor) depends on defect length
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Comparison
Criterion Original B31G 0.85dL Method Effective Area
Flow stress 1.1SMYS SMYS + 10,000psi SMYS + 10,000psi
Defect area𝑑𝐿 𝑜𝑟
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3𝑑𝐿
0.85𝑑𝐿 Effective Area
Transition length 20𝐷𝑡 50𝐷𝑡 50𝐷𝑡
Folias factors 1 2 2
Defect model 2 1 Corrosion Profile
Pressure model 2 1 1
• Improved performance achieved by adjusting the bulging stress magnification factor (Folias factor) for the length of the defect
and maintaining a single failure stress (pressure) model
• Effective area is the best method for estimating the remaining strength of the pipe (hence the term rstreng)
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0
2
4
6
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10
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0 10 20 30 40 50 60 70 80 90 100 110 120
ASME B31G Folias Factor Comparison
𝑀0.85𝑑𝐿 = 1 + 0.6275𝐿2
𝐷𝑡− 0.003375
𝐿2
𝐷𝑡
2
𝑀0.85𝑑𝐿 = 0.032𝐿2
𝐷𝑡+ 3.3
𝐿2
𝐷𝑡
𝑀𝐵31𝐺 = 1 +0.8𝐿2
𝐷𝑡
𝐿2
𝐷𝑡≤ 50
𝐿2
𝐷𝑡> 50
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Maxey’s Surface Flaw Equation
A second look
𝜎 = 𝜎𝑜
1 −𝐴𝐴𝑜
1 −𝐴
𝐴𝑜𝑀
𝐴 = 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑑𝑎𝑚𝑎𝑔𝑒
𝑑 = 𝑑𝑒𝑝𝑡ℎ 𝑜𝑓 𝑎 𝑑𝑒𝑓𝑒𝑐𝑡
𝐴𝑜 = 𝐿𝑡
𝑀 = Bulging stress magnification factor (Folias factor)
t
D
D
direction of flow
t
d
L
What’s the best
method to
estimate the area
of damage, A?
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Effective Area
Better calculation of the area of damage
Does not depend on a specific defect model
Parabolic, rectangular, or otherwise
Requires detailed data regarding the shape of the infrastructure damage
One step closer to a FEA (finite element analysis) for damage assessment
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DETERMINATION OF BURST PRESSURE
– TWO EXAMPLES
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• Broad area
corrosion
• Data collected
using a 3D surface
measurement tool
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• Corrosion damage
analyzed to
determine depth
and extent of metal
loss
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ASME B31G-2012 Revision
Fitness for Service Determination
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Defect length = 12.389”
𝐿 ≤ 20𝐷𝑡 = 17.321“
Area model for ASME B31G (1991)
𝐴𝐵31𝐺 =2
3𝐿𝑑 = 1.148 𝑖𝑛2
Area model of 0.85dL
𝐴0.85𝑑𝐿 = 0.85𝑑𝐿 = 1.464 𝑖𝑛2
Area model Effective Area
𝐴𝐸𝐴 = 0.860 𝑖𝑛2
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Effective Area
Area Estimate Comparison
Defines Original ASME B31G
boundary for area estimation
Defines 0.85dL boundary
for area estimation
Area model for ASME B31G (1991)
𝐴𝐵31𝐺 =2
3𝐿𝑑 = 1.148 𝑖𝑛2
Area model of 0.85dL
𝐴0.85𝑑𝐿 = 0.85𝑑𝐿 = 1.464 𝑖𝑛2
Area model Effective Area
𝐴𝐸𝐴 = 0.860 𝑖𝑛2
Corrosion (River bottom) Profile
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• Isolated pits that
likely interact to
form a single
defect
• Data collected
using a 3D surface
measurement tool
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• Isolated pits that
likely interact to
form a single
defect
• Data collected
using a 3D surface
measurement tool
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Defect length = 141mm
𝐿 ≤ 20𝐷𝑡 = 225𝑚𝑚
Area model for ASME B31G (1991)
𝐴𝐵31𝐺 =2
3𝐿𝑑 = 408 𝑚𝑚2
Area model of 0.85dL
𝐴0.85𝑑𝐿 = 0.85𝑑𝐿 = 520 𝑚𝑚2
Area model Effective Area
𝐴𝐸𝐴 = 263 𝑚𝑚2
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Defines Original ASME
B31G boundary for area
estimation
Defines 0.85dL boundary
for area estimation
Corrosion (River bottom) Profile
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INTEGRATION WITH NDT TOOLS
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Integration with NDT tools
Seikowave Tools
3DSL Rhino
3D Toolbox
Ultrasound
Olympus
Other 3D surface measurement tools
Handyscan 700
Coordinate Measurement Machines (e.g. Mitutoyo)
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Need 3D data in
ply or stl format
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WHAT’S NEXT?
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• Complexity
• Difficult to acquire the
data
• Difficult to perform the
calculation
• Conservatism
• More conservative
generally means more
cost to maintain
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ASME B31G-2012 includes
• Expanded definition of flow stress
• Applicability to metal loss in field bends,
induction bends and elbows
ASMEB31G-2012 does not include
• Preferential corrosion affecting pipe
seams or girth welds
• Metal loss in fittings other than bends
and elbows
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ASME B31G (2012) Flow Stress
Material SMYS Temperature Flow Stress
Carbon Steel T < 250F (120C) sflow = 1.1 X SMYS
sflow < SMTS
Carbon Steel
and low-alloy
Steel
T < 250F (120C) sflow = SMYS + 10kpsi (69MPa)
sflow < SMTS
Carbon Steel
and low-alloy
Steel
sflow = (sYT + sUT)/2
sYT and sUT are specified at the
operating temperature (YT is
the yield strength and UT is the
ultimate strength in tension)
ASME B31G-2012 Revision
𝑆𝑀𝑌𝑆 ≤ 70𝑘𝑝𝑠𝑖 (483MPa)
𝑆𝑀𝑌𝑆 ≤ 80𝑘𝑝𝑠𝑖 (551MPa)
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Flow Stress Examples
SMYS SMTS 1.1 SMYS
SMYS + 10kpsi
(69MPa) (SMYS+SMTS)/2
ksi Mpa ksi Mpa ksi Mpa ksi Mpa ksi Mpa
X65 65 448 77 531 71.5 493 75 517 71 490
X80 80 551 90 621 88 607 90 621 85 587
X100 100 690 110 759 110 759 110 759 105 725
𝑃𝑏𝑢𝑟𝑠𝑡 =𝜎𝑓𝑙𝑜𝑤2𝑡
𝐷
1 −2𝑑3𝑡
1 −2𝑑3𝑡𝑀
• For X65, Pburst is higher when using SMYS + 10kpsi
• For X80, SMYS + 10kpsi equals SMTS
• For X100, 1.1SMYS and SMYS + 10kpsi = SMTS
• Average of SMYS and SMTS is more conservative but
• ASME B31G-2012 does not cover pipe with SMYS > 80kpsi
Subject of ongoing PRCI studies
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Remaining Strength Assessment
What’s Available Now
Original ASME B31G
Modified 0.85dL
Effective Area
API 579
Level 1 and Level 2
What’s Next (Q2 2016)
Pit Gage Data Entry
Robotic Collection
Additional Capabilities
Expanded definition of flow stress
DNV RP-F101
• Per DNV RP-F101, applicable for corrosion in girth welds and seam welds
• Applicable for temperatures above 250F (120C)
Kastner (Circumferential corrosion analysis)
• Better solution for examining extensive circumferential corrosion
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Pit Gage Data Entry
Data from NDT tools is not always available
Sometimes a pit gage is all you have
Data entry in a grid format that matches the grid drawn on the pipeline
Integrates with existing database
Integrates with existing flaw detection and interaction rule software
Integrates with Pipeline FFS for fitness for service calculations
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.034 0.037 0.035 0.000 0.000 0.000
0.000 0.000 0.036 0.050 0.058 0.056 0.038 0.000 0.000
0.034 0.034 0.039 0.052 0.060 0.059 0.048 0.000 0.000
0.037 0.037 0.040 0.052 0.054 0.221 0.049 0.042 0.041
0.036 0.037 0.037 0.035 0.041 0.043 0.041 0.044 0.048
0.000 0.033 0.035 0.039 0.040 0.038 0.139 0.111 0.045
0.000 0.000 0.045 0.090 0.122 0.038 0.037 0.041 0.041
0.000 0.000 0.036 0.037 0.036 0.036 0.038 0.041 0.041
0.000 0.000 0.000 0.000 0.037 0.038 0.041 0.041 0.039
0.000 0.000 0.000 0.035 0.039 0.038 0.039 0.039 0.034
0.000 0.000 0.000 0.034 0.034 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000
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Robotic data collection
Seikowave robotic systems can move omni-directionally over surfaces and can be operated remotely enabling collection of3D inspection data
Other inspection data (e.g. UT, eddy current)
UntetheredAble to operate as far as 300
meters from the base station
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Seikowave systems
navigating and
measuring inside and
outside of pipes (1)
(1) Photos courtesy of Asahi and ExxonMobil
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FEA – Under Development
𝑃𝑐𝑜𝑚𝑝𝑢𝑡𝑒𝑑
𝑃𝑏𝑢𝑟𝑠𝑡 𝑡𝑒𝑠𝑡< 1 𝑡ℎ𝑒𝑛 𝑐𝑜𝑚𝑝𝑢𝑡𝑎𝑡𝑖𝑜𝑛 𝑖𝑠 𝑐𝑜𝑛𝑠𝑒𝑟𝑣𝑎𝑡𝑖𝑣𝑒
More work still needed but shows promise
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COME TO THE PRCI RESEARCH
EXCHANGE TO LEARN MORE
February 2-4, 2016 at the Omni San Diego Hotel in San Diego, CA