An Advanced Approach to Fitness-For-Service (FFS) and Corrosion ...

An Advanced Approach to Fitness-For-
Service (FFS) and Corrosion Growth
Assessment to Ensure Effective Pipeline
Integrity Management
by Iain K. Richardson

Iain K. Richardson
BEng(Hons.) CEng MIMechE
Past Experience
� 1996 – 1999 : Applications Engineer with Vickers plc. – Michell Bearings.
� 1999 – 2002 : Development Engineer with PII Pipeline Solutions (GE-PII)
� 2002 – 2009 : Global Sales & Marketing Manager with Rolls-Royce plc. –
Michell Bearings
Current Role (2009 - )
� Senior Integrity Engineer within MACAW's Pipeline Integrity Group
which provides services relating to pipeline risk assessment, corrosion
management, fitness for service and corrosion growth assessments for
clients world-wide.

� Purpose of Presentation
� To demonstrate the steps taken to provide the client with
a Fitness-for-Service Assessment, utilizing detailed
Corrosion Growth methods to ensure ongoing operation
and safety of a 12” x 30 mile refined product pipeline.
� Data Sources
� ROSEN In-Line Inspection Survey Report (0-1000-11210),
August 2009
� ROSEN/MACAW Fitness-For-Service Report, March 2010.

Scope of Work
• Review findings of the latest intelligent pig inspection and
identify potential causes of corrosion.
• Assess significance of the reported anomalies (corrosion / other)
in terms of immediate integrity of the pipeline.
• Identify and prioritise anomalies which require immediate repair
(in-line with DOT 49CFR195 regulations).
• Utilize available pipeline information and recent & previous
inspection data sets to estimate appropriate corrosion growth
rates.
• Develop a rehabilitation plan for the pipeline, including a long
term repair plan.
• Recommend appropriate repair methods for any repairs
identified.
• Identify an appropriate re-inspection interval.

Pipeline Summary
• 12” x 30 mile refined product pipeline.
• Constructed in 1975 from seamless pipe.
• API 5L Grade X42.
• The nominal wall thickness varies from 0.188” to 0.322”.
• Reported Maximum Operating Pressure (MOP) is 850 psi.
• Tar Tape Wrap Coating.
• Impressed current CP system.
• Inspected in 2009 by ROSEN (CDX) and in 2006 by ROSEN
(CDP & EGP).

Summary of Inspection Findings
Feature Type 2006 Inspection 2009 Inspection
External Corrosion 2434 2455
Manufacturing Anomalies 178 196
Girth Weld Anomalies 1 2
Dents 31 43
Deformation Anomalies 715 485
Extra Metal 5 4
Eccentric Casings 5 0
Repairs (metal sleeves &
composite wraps)
0 778

Internal Corrosion
• The pipeline transports refined product.
• Therefore a low level of water would be expected internally.
• A corrosion inhibitor is injected into the product.
• Both the 2006 and the 2009 inspections did not report any
internal corrosion features.
• On this basis the threat of internal corrosion is considered to
be low in this pipeline.

External Corrosion
Orientation - Degrees
360
315
270
225
180
135
90
45
0
0 5 10 15 20 25 30
Distance - miles
External Corrosion Features 10 to 20%WT External Corrosion Features 21 to 30%WT
External Corrosion Features 31 to 40%WT External Corrosion Features 41 to 50%WT
External Corrosion Features 51 to 60%WT External Corrosion Features 61 to 70%WT
External Corrosion Features 71 to 80%WT
• Area of low level external corrosion in the first ~7 miles.
• Concentration of deeper (79%wt) external corrosion features
between ~7.2 - 9.4 miles close to rectifier.
• Two concentrations of deeper external corrosion features at
the end of the pipeline at ~28 miles.
1400
1200
1000
800
600
400
200
0
Elevation (ft)

External Corrosion
• Location 1: 0-7 Miles
– Depleted ground bed at the start of the line - CP underprotection
– Ground bed to be re-instated
• Location 2: 7.2-9.4 Miles
– Coating disbondment
– Rectifier no power (between 2004-2006)
• Location 3: at ~28 Miles
– Two foreign line crossings, potential stray current issue
– Corrosive soil, resistivity of 1000 Ω-cm, poor coating condition
– Rectifier to be installed to raise potentials, or re-coating of ~5
miles
• Large number of repairs completed including remedial work on
CP system
• A potential disbonded coating issue remains

External Corrosion
Signal comparison showing evidence of disbonded coating
• Potential for microbial corrosion to occur in areas of anaerobic
soil

Manufacturing Anomalies
Orientation - degrees
360
315
270
225
180
135
90
45
0
0
0 5 10 15 20 25 30 35
Distance - Miles
Orientation Elevation
• The majority (91%) are

Girth Weld Anomalies
• The 2009 inspection reported 2 metal loss girth weld
features.
• The anomalies are considered to have been introduced
during the construction process.
• Are considered to have survived any pre-service hydrostatic
pressure test.
• In the absence of a growth mechanism, they are not
expected to affect the integrity of the pipeline.

Dent / Deformation Anomalies
Orientation (degrees)
360
315
270
225
180
135
90
45
0
0
0 5 10 15 20 25 30
Distance (Miles)
• 485 deformation anomalies less than 2% OD
• 43 dents greater than 2% OD, the deepest of which was reported to
be 4.4% OD.
1400
1200
1000
800
600
400
200
Concentration
in particularly
rocky area
Elevation (ft)

Dent / Deformation Anomalies – DOT Requirements
Position of
Feature on
Pipeline
Top of line
(above 4-8
o’clock)
Bottom of line
(between 4-8
o’clock)
On Girth
Weld/Seam
Weld
Priority 1 - Immediate Priority 2 – 60 day Priority 3 – 180 day
Repair
Condition
Depth
>6%OD or
With
associated
metal loss,
cracking or
stress riser
Number of
Features
32
N/A N/A
Repair
Condition
Depth
>3%OD
With
associated
metal loss,
cracking or
stress riser
Number of
Features
2
89
N/A N/A N/A N/A
Repair
Condition
Depth
>2%OD
Depth
>6%OD
Depth
>2%OD
TOTAL 32 91 4
Number of
Features
4
0
0

Extra Metal Anomalies
Orientation - degrees
360
315
270
225
180
135
90
45
0
0
0 5 10 15 20 25 30 35
Distance - Miles
Orientation Elevation
• Extra metal features close to or touching the pipeline can
damage the protective coating and/or affect the performance
of the cathodic protection system.
• There is no external corrosion located in the vicinity of these
features, therefore they are considered to be insignificant in
terms of the integrity of the pipeline.
1400
1200
1000
800
600
400
200
Elevation - ft

Immediate Integrity Assessment
• Assessment Pressure: MAOP 850 psi
• The corrosion anomalies were assessed:
– to Modified B31G in terms of their axial dimensions
– Anomalies that require repair within 5 years have also
been assessed to Detailed RSTRENG
– Kastner in terms of circumferential dimensions
• The manufacturing and girth weld features were assessed to
Shannon and Kastner
• Anomalies require repair if:
– Their reported dimensions exceed the size tolerable at the
MAOP x safety factor (1.39); or
– Their maximum reported depths exceed 80% wt.
• The assessment has been conducted allowing for tool depth
sizing tolerances

Peak Depth (%wt)
Immediate Integrity – Axial Dimensions
100
90
80
70
60
50
40
30
20
10
0
0 5 10 15 20 25 30 35 40
Axial Length (inch)
Modified B31.G @ Assessment Pressure (68% SMYS, 58.6 bar)
Modified B31.G @ Assessment Pressure x 1.39 (95% SMYS, 81.5 bar)
External Corrosion Features
Features Reported as Repaired in ROSOFT
• 45 corrosion features were found to be unacceptable
• Assessment to Detailed RSTRENG reduces the number of
unacceptable corrosion features to 24

Immediate Integrity – Circumferential Dimensions
Peak Depth (%wt)
100
90
80
70
60
50
40
30
20
10
0
0 5 10 15 20 25 30 35 40
Circumferential Length (inches)
Kastner @ Assessment Pressure (34% SMYS, 58.6 bar)
Kastner @ Assessment Pressure x 1.39 (48% SMYS, 81.5 bar)
External Corrosion Features
Features Reported as Repaired in ROSOFT
• 4 external corrosion features were found to be unacceptable
• These were also found to be unacceptable in terms of their
axial and depth dimensions (with tolerances).

Immediate Integrity – Manufacturing / Weld Anomalies
Peak Depth (%wt)
100
90
80
70
60
50
40
30
20
10
0
0 1 2 3 4 5 6
Axial Length (inches)
Shannon @ Assessment Pressure (68% SMYS, 58.6 bar)
Shannon @ Assessment Pressure x 1.39 (95% SMYS, 81.5 bar)
Manufacturing/weld Anomalies
Peak Depth (%wt)
100
90
80
70
60
50
40
30
20
10
• All of the
manufacturing /
weld anomalies
were found to be
acceptable
0
0 1 2 3 4 5 6
Circumferential Length (inches)
Kastner @ Assessment Pressure (34% SMYS, 58.6 bar)
Kastner @ Assessment Pressure x 1.39 (48% SMYS, 81.5 bar)
Manufacturing/weld Anomalies

DOT 49CFR195 High Consequence Area Requirements
Immediate Repair
• Calculation of the remaining strength of the pipe (using ASME/ANSI B31G;
RSTRENG) shows a predicted burst pressure less than the established maximum
operating pressure at the location of the anomaly.
• In addition any metal loss greater than 80% wt is also considered to be an
immediate repair regardless of the feature dimensions.
180 – Day Conditions
• Calculation of the remaining strength of the pipe shows an operating pressure
that is less than the current established maximum operating pressure at the
location of the anomaly. For this pipeline this has been calculated by assuming
that the pipeline is operating at 72% SMYS resulting in a safety factor of 1.39.
• An area of general corrosion with a predicted metal loss greater than 50% wt.
• Predicted metal loss greater than 50% of nominal wall that is located at a
crossing of another pipeline, is in an area with widespread circumferential
corrosion, or is in an area than could affect a girth weld.
• Corrosion of, or along a longitudinal seam weld.
To maintain safety prior to any immediate repairs an operator must temporarily
reduce the operating pressure or shut down the pipeline until the operator
completes these repairs.
On the basis of the above, 1 external feature requires immediate repair and 12
external features require remediation within 180 days of the date of discovery.

Corrosion Growth Assessment
• CGA conducted in two stages:
– Feature matching between 2006 and 2009 inspections
– Align inspection data to common distance
– Comparison of reported feature lists to identify features
reported in both inspections
– Estimation of growth rates based on reported
dimensions
– Signal-based comparison to validate the growth rates
– Review of 2006 and 2009 inspection signals for
selected features

Feature Matching Process
Collect recent
inspection
information
(Feature location,
depth, length,
width)
Define search
window size
(standard is ± 10cm)
Does any previous
feature overlap with the search
window?
Yes
Is there more
than one previous feature
overlapping?
Yes
Select the
previous feature
with the maximum
depth
No
Move to next
feature
No
No
Is there more
than one recent feature
overlapping?
MATCH FOUND
Select the recent
feature with the
maximum depth
Yes

Feature Matching Process
• Distance Correlation
– Use the weld distances to align the inspections
– Unique patterns present in weld locations
• Distance Adjustment
– Apply the weld adjustment to the features
• Feature Comparison
– Compare the feature locations in both inspections to find a match

Feature Matching Process
Previous
Inspection
Recent
Inspection
12:00
06:00
12:00
12:00
06:00
12:00
Reported
location
Reported
location
Reported
feature width
Reported
feature length
User defined
search window
size

Feature Matching Process
65%
55%
37%
18%
23%
39%
Previous
Inspection
Recent
Inspection
52%
83%
50%
45%
51%
51%

Depth (%wt)
Corrosion Depth Comparison
100
90
80
70
60
50
40
30
20
10
0
0 5 10 15 20 25 30
Log Distance (miles)
2006 2009 Features Reported as Repaired in ROSOFT
• The majority of the external corrosion occurring on the pipeline
appears to be controlled

Corrosion Growth Signal Comparison
~ 2m / 6.5ft
Previous Inspection
Recent Inspection

Corrosion Growth Signal Reorientation

Corrosion Growth Signal Normalization

Corrosion Growth Signal Comparison
Clear
Evidence
of growth
No clear
Evidence
of growth

Example Signal Comparison
• Feature with highest confirmed external corrosion growth rate

Corrosion Growth Rate (mils/yr)
Signal Comparison Results
60
50
40
30
20
10
0
-10
-20
From
(miles)
To
(miles)
-30
0 5 10 15 20 25 30
Log Distance (Miles)
Corrosion
Growth Rate
Applied
(mils/yr)
0 27.9 11.4
27.9 End of Pipeline 47.5
Existing Corrosion Growth New Corrosion Growth
Features showing evidence of Corrosion Growth Outlier Feature for Investigation
Minimum Statistical CGR Threshold CGR updated following Signal Comparison

Further Investigations
• 1 feature at 37226.75 ft reported as repaired but not present in
2006 inspection
– Confirm that feature has been repaired
• 1 feature showing evidence of new growth at 45578.69 ft, above
statistical limit
Distance
(ft)
– Confirm origin and take steps to remove threat as appropriate
37226.75 MELO-
CORR
45578.69 MELO-
CORR
Type O’clock
Position
Length
(in)
Width
(in)
Depth
(% wt)
Corrosion
Growth Rate
(mils/yr)
04:31 1.535 1.654 64 40
09:25 0.591 0.63 32 20

Future Integrity
400
350
300
250
200
150
100
50
0
Predicted Investigations/Repairs 0-28 miles
2009 2010 2011 2012 2013 2014
Predicted Repairs per Year 2 1 12 28 44 33
Accumulated Repairs 2 3 15 43 87 120
28 miles to end
of pipeline
360 features over
5 years
Predicted Repairs per Year Accumulated Repairs
400
350
300
250
200
150
100
50
0
Predicted Investigations/Repairs 28 miles to end of Pipeline
2009 2010 2011 2012 2013 2014
Predicted Repairs per Year 7 65 140 148 0 0
Accumulated Repairs 7 72 212 360 360 360
Predicted Repairs per Year Accumulated Repairs
0-28 miles
120 features
over 5 years

Future Integrity
Number of Single Repairs
160
140
120
100
80
60
40
20
0
0 5 10 15 20 25 30
Log Distance (miles)
2009
2010
2011
2012
2013
Year
2014

Rehabilitation Strategy
• Conduct Sectional Repairs/re-coating
• Complete planned mitigation measures
– Replacement of the depleted ground bed at start of pipeline
– Installment of a rectifier and deep well ground bed at 25
miles or recoating of the last 5 miles of the pipeline
– It is noted that if coating disbondment is a particular issue in
this area, then either sectional replacement or recoating of
the pipeline would be required to control the corrosion
• Conduct re-inspection in 3 years, this will:
– Ensure any further areas of coating disbondment are
identified
– Enable confirmation of external corrosion growth rates
predicted here
– Confirm the effectiveness of any planned mitigation
measures
– Ultimately assist in reducing the numbers of repairs required
in subsequent years

Repair Methods
Type of Defect Grinding
Leak or Defect
>80% wt
External
Corrosion

Recommendations – External Corrosion
• Carry out planned mitigation work
• Complete immediate investigations/repairs
• During investigations:
– A check should be made to determine if CP shielding
problems exist due to disbonded coating
– If this is the case then the area should be recoated
– During the removal of any coating the existence of
MIC can be confirmed by the presence of the smell of
hydrogen sulphide
• Investigate two corrosion features which produced
unrepresentatively high calculated corrosion growth rates
• Confirm with available records which features have been
repaired

Recommendations – External Corrosion
• Consider the potential benefits of the suggested
rehabilitation strategy in terms of cost and future
operational requirements
• If in-field investigations confirm that predicted corrosion
growth rates are not conservative, or they are overly
conservative, then the repair schedule should be
redefined on the basis of a revised corrosion growth rate
• The findings of field verification data should be analysed
and compared with the dimensions reported by the ILI
tools
• If the results of the excavations indicate that the addition
of sizing tolerances is an over conservative assumption,
then this study should be reviewed

Recommendations – Dents
• For those features located in HCAs, DOT 195 has
particular time requirements split into:
– Immediate, 60-day and 180-day conditions and
correspond to priority 1, 2 and 3 respectively
– In addition the operating pressure must be
temporarily reduced or the pipeline shut down until
any immediate repairs are completed
• The following dents/deformation anomalies have been
highlighted for investigation:
– 32 features have been highlighted as priority 1
investigations
– 91 features have been highlighted as priority 2
investigations
– 4 features have been highlighted as priority 3
investigations

Recommendations – Re-Inspection Interval
• If it can be confirmed that coating disbondment issues on
the pipeline have been resolved then the re-inspection
interval could in theory be extended to 5 years
• However there is a large uncertainty associated with this
and a risk that features initiated now could fail within 5
years, if they are growing at the rates calculated in this
report.
• Therefore a reinspection interval of 3 years is
recommended i.e. re-inspect before the end of August
2012.

Recommendations – Post Re-Inspection
• An integrity assessment should be carried out to:
– Determine the significance of the reported features
– This should be based on actual depths at the time of
new inspection rather than those predicted from this
inspection
– Provide confirmation that the mitigation measures put
in place have controlled the threat of external
corrosion to this pipeline
– Identify areas of probable CP shielding, where
adequate “off”-potentials have been recorded, but ILI
data show continued growth
• This should assist with ensuring the future integrity of the
pipeline

Iain K. Richardson
MACAW Engineering Ltd
Thank you for your attention
Tel. +44 (0)191 216 4300
Email. iain.richardson@macawengineering.com
Web. www.macawengineering.com