8. Aim of Monitoring & Inspection
• Pipelines do not become defective or damaged
• Damage or defects are detected before they cause
serious problems ('reactive' methods).
11. Pipeline Risk Scores for Risk
Source: Anon., 'Interstate Natural Gas Pipelines - Delivering Energy
Safely’, Dept. of Transportation, DoT/NTB, USA, 1994.
12. RBI Analysis
Probability Consequence Risk Inspection
CO2 Corr. H H H UT-WT
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
Sulfide stress corrosion cracking (SSC) and hydrogen-
Hydrogen embrittlement and exfoliation that leads
to various modes of failure.
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.
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
Water free triazine Hot streams: bitumen, fuel oil 1.6
Metal salts Bitumen 2.5
Amine LPG, gas streams 0.33
Water free aldehyde
Hot streams: bitumen, fuel oil 1.15
Non amines: Water based
Crude, finished fuel, water 0.9
Table: H2S scavengers and their applications
16. POTENTIAL PIPE SUPPLIERS
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.
17. POTENTIAL SUPPILERS FOR CORROSION
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.
18. OTHER IMPORTANT FACTORS
WHICH MAY BE OF CONCERN
1. Consistent wetting and drying of splash zone
2. Defects in coating
3. Stray Current
1. Sulphate reducing bacteria- MIC
2. Flow rate
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
Methods to reduce potential issues due to sour fluids:
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 %
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-
A report by Rolf Nyborg, Controlling Internal Corrosion in
Oil and Gas Pipelines.