1. Design of an
Export Pipeline
Group 14
Sarah Busef, Barathkumar Krishnan, Siyu Zhang
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2. Outline
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3. Introduction
 Offshore Pipeline Design
 Environment: Temperature, Flow rate, Pressure,
Flow Density, CO2, Nacl, Bicabonate
 Material: X-65 carbon steel
 Cost-Effective
 Safe and Durable(better weldability and tensile
stress.)
 Environmentally Friendly
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4. Pipeline Specifications
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Inlet Temperature 55 °C
Flow Pressure 100 bar
107 Pa
Length 150 km
Throughput 1.5×106 bbl/d
Water Cut 1.1 - 2 %
Fluid Density 800 kg/m3
Design Lifetime 25 Years
Empirical constant, C 1 122 -
Design Factor 1 0.72 -
Yield Strength 2 450 MPa
Corrosion Allowance, CA 8 mm
Fluid Flow Rate
2.76 m3/s
Critical Fluid Flow Rate for
Erosion
4.31 m3/s
Pipe Inner Diameter
903 mm
Pipe Outer Diameter
930 mm
Pipe Thickness
13.5 mm + compensation for
loss
Pipe Cross Sectional Area
0.640 m2
1 BS ISO13703:2000
2 Stock Specifications: Pipes ArcelorMittal (2013)

5. Plain-end Line Pipe
Dimensions (API 5L)
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Source: API 5L: Specification for Line Pipe
Dimension Calculated (in.) Standard (in.)
Outer Diameter 36.60/37.23 38
Wall Thickness 0.532/0.847 0.562/0.875
Inner Diameter 35.54 36.876/36.250

6. Corrosion Rate: Norsok
 Uninhibited Corrosion Rate: 5 mm/y
 Pipe Thickness: 22 mm
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7. Level of Inhibition
 Required Availability (A%): 95%
 Required Concentration: 100 ppm
 CA: 0.30 mm/y
 Corrosion Inhibitor Risk: High
 Inhibition required for lifetime available from day 1
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90
91
92
93
94
95
96
97
98
99
100
0 10 20 30 40 50 60 70 80 90 100 110
Efficiency(%)
Concentration (ppm)
𝐴% =
100 𝐶𝐴−𝐶𝑅 𝑢× 𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒
𝐿𝑖𝑓𝑒𝑡𝑖𝑚𝑒× 𝐶𝑅 𝑖−𝐶𝑅 𝑢
𝐴% =
−468
𝐶𝑅 𝑖−5
Concentration
(ppm)
Efficiency
(%)
CRi A%
10 91 0.45 102.86
20 95 0.25 98.53
30 97 0.15 96.49
40 97.5 0.125 96.00
50 98 0.1 95.51
100 99 0.05 94.55

8. Aim of Monitoring & Inspection
• Pipelines do not become defective or damaged
('proactive' methods)
• Damage or defects are detected before they cause
serious problems ('reactive' methods).
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9. Conditions to Consider:
Monitoring
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• Environment
• Corrosion types
• Size of pipeline
• Time we need to monitor
• Economic cost
Corrosion coupons or ER probes

10. RBI
Hydrostatic
test
RBI
MFL
pigging
Inspection
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• Cost-effective
• Less operators
• Run in operation
but
• Need launch and
receive facilities
• Big enough for pig
• Provides limited information
about the condition
• Higher cost
• Cost-effective
• Group
inspection
• Identify
corrosion risk

11. Pipeline Risk Scores for Risk
Based Inspection
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Source: Anon., 'Interstate Natural Gas Pipelines - Delivering Energy
Safely’, Dept. of Transportation, DoT/NTB, USA, 1994.

12. RBI Analysis
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Probability Consequence Risk Inspection
Technique
CO2 Corr. H H H UT-WT
Chloride
Pitting
H H H UT-WT
SSC H H H UT-WT
Erosion Corr. L H L UT-WT
Oxygen Corr. L H L UT-WT
Microbial Corr. L H L UT-WT
Crevice Corr. L H L UT-WT
Fatigue H H H ECL
External Corr. H H H CVI
UT-WT: Ultrasonic technique- Wall thickness
ECL: Eddy Current Inspection
CVI: Close: Visual Inspection

13. Methods to Minimize Potential
Issues due to Sour Fluids
 Materials in the sour environment are susceptible
to:
 Sulfide stress corrosion cracking (SSC) and hydrogen-
induced cracking,
 Hydrogen embrittlement and exfoliation that leads
to various modes of failure.
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14. pH STABILIZATION
 Corrosion rate due to the transport of sour fluids can be reduced
by increasing the pH of the water phase.
 Enhances the precipitation of protective corrosion product films on
the steel surface.
 FeS films are formed as protective film.
 Corrosion rate decreases: pH 4-5
 Corrosion rate increases: pH 6-8.
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15. H2S SCAVENGERS
 Proper selection and application can effectively lower H2S levels
 Important selection criteria: properties, effectiveness and impacts of
chemicals used to reduce H2S
 In oilfield, Triazine: benchmark H2S scavenger used for decades.
Chemical Family Application Relative treat rate (l/kg H2S)
Water based triazine Crude, LPG, finished fuel, gas
stream
1
Water free triazine Hot streams: bitumen, fuel oil 1.6
Metal salts Bitumen 2.5
Amine LPG, gas streams 0.33
Water free aldehyde
derivatives
Hot streams: bitumen, fuel oil 1.15
Non amines: Water based
aliphatic aldehydes
Crude, finished fuel, water 0.9
Table: H2S scavengers and their applications
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16. POTENTIAL PIPE SUPPLIERS
 KELLY PIPE:
Based in California-USA, Kelly pipe has been the industry leader
amongst carbon steel pipe suppliers in US and abroad since 1898.
 MAY OILFIELD PIPE:
Based in the USA, they are in the market for almost 60 years.
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17. POTENTIAL SUPPILERS FOR CORROSION
INHIBITORS
 INTERNATIONAL CHEMICAL COMPANY:
Based in Philadelphia-USA, International Chemical Company have been
manufacturing chemicals for the past 100 years.
 WEGO CHEMICAL GROUP:
Based in USA, Wego has been operating for over 35 years as a
renowned and reliable international chemical supplier.
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18. OTHER IMPORTANT FACTORS
WHICH MAY BE OF CONCERN
 External corrosion:
1. Consistent wetting and drying of splash zone
2. Defects in coating
3. Stray Current
 Internal corrosion:
1. Sulphate reducing bacteria- MIC
2. Flow rate
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19. Summary and Conclusion

 Monitoring & Inspection
 Depends on corrosion environment and economic cost, ER probes
are suitable for monitoring in this case, RBI can be used for
inspection part
 Methods to reduce potential issues due to sour fluids:
 pH stabilization
 H2S scavenger
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Pipeline Inner Diameter 36 in.
Pipeline Outer Diameter 38 in.
Minimum Wall Thickness 1 in.
Uninhibited Corrosion Rate 5 mm/y, 197 mpy
Inhibited Corrosion Rate 0.30 mm/y, 12 mpy
Inhibitor Concentration 100 ppm
Inhibitor Availability 95 %

20. Thank you
Questions?
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21. References
 http://petrowiki.org/Corrosion_problems_in_production
 Jiabin Han, Jinsuo Zhang, J. Wiliam Carey, Volume 5, Issue
6, November 2011, Pages 1680–1683, Effect of bicarbonate
on corrosion of carbon steel in CO2saturated brines.
 Michael Baker Jr., Inc., November 2008, Pipeline Corrosion-
Final Report.
 A report by Rolf Nyborg, Controlling Internal Corrosion in
Oil and Gas Pipelines.
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22. Extra Slide:
Inhibition/Concentration
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0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 20 40 60 80 100 120
CORROSIONRATE(MM/Y)
INHIBITOR CONCENTRATION (PPM)
INHIBITED CORROSION RATE VS.
INHIBITOR CONCENTRATION