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CORROSION OF STEELCORROSION OF STEEL
STRACTUR IN SEA BEDSTRACTUR IN SEA BEDSEDIMENTSEDIMENT
GUIDE BY:
MR.SANJAY KU. SAHOONAME:GAUTAM BEHERA
B TECH 7 th sem
REGD NO:0701105083ROLL NO:26602
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CONTENTS
INTRODUCTION SBS CORROSION FACTOR
SBS CORROSION MECHANISM MEASUREMENT OF METALCORROSION RATE IN SBS
SBS CORROSION EVALUATIONAND PREDICTION CONCLUSIONS
REFERENCE
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INTRODUCTIONv Sea bed sediment (SBS) corrosion is animportant topic in marine environment
corrosion science. In terms of corrosionlocality, marine environment can be dividedinto atmospheric zone, splash zone, tidal
zone, immersed zone, and seabed sedimentzone. Generally it is considered that theseabed sediment zone has leastcorrosiveness. Development in marine oilexploitation and engineering including marine
cables, steel rigs, pipelines and other marinefacilities is increasing demanding integratedinvestigation and research on corrosion.Therefore, scientific solution and referenceto corrosion in marine oil exploitation andsea bed pipelines can be provided.
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SBS COROSION FACTOR
SBS defination: SBS is a special soilbeneath sea water. It is soaked tosome extent. In this two-phasedsystem, there is no sole gas phase.
Physical and chemical character:
Different from land soil,salina soil& tideland soil.
Factors on which SBS corrosion
depends
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ELECTRO CHEMICAL CORROSION FACTOR
Temperature
Particle size
Electrical resistance Salinity
Dissolved oxygen
PH value
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q INFLUENCE OF TEMPERATURE Affect the kinetics process of
electrode reaction Direct relationship
q INFLUENCE OF PARTICLE SIZE SBS division on basis of particle size Relationship between particle size and
corrosion rate
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FIGURE 1 SHOWS THREE YEAR CORROSI RATE OF DIFFERENT STEELS N MUD AN
SAND
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FIGURE 2 SHOWS THE CORROSION RATE WITH DIFFERENT GRAIN SIZE
OF MILD STEEL
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q INFLUENCE OF ELECTRICAL
REISTANCE Reflection of SBS electricalconductivity
Resistance increases with burialdepth
Relationship between electricalresistance and SBS particle size
q INFLUENCE OF SALINITY General salinity including SBS Relationship between salinity and
corrosion rate Effect of CL ions
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q INFLUENCE OF pH VALUE
Sea water a complicated system pH of surface layer SBS Effect of Alkalophilic bacterium on pH
value of SBS Favourable for propagation of
anaerobic bacteria
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MIC FACTOR
Include SRB
Redox potential (Eh)
Sulfur potential (Es) Ratio of Fe to Fe
Organism content
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q SRB CONTENT MIC is mainly SRB corrosion Wider distribution in sea SRB content in Liaodong Bay SBS
is 0 ~ 460 unit per g wet mud SRB content in south china sea
SBS is 0 ~ 9.3
Effect of SRB on corrosion rate
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GRAPH 3 SHOWS CORROSION RATE OF DIFFERENT STEEL IN SEA MUD WITH
BACTERIA
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q , , /Eh Es Fe Feand organismcontent
All affect SRB corrosion Favorable anaerobic condition for SRB
growth
Effect of SRB growth in marineenvironment
Other factors of corrosion
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SBS CORROSION MECHANISM
Electrochemical corrosionmechanism
MIC mechanism
q ELECTROCHEMICAL CORROSIONMECHANISM
Galvanic corrosion Localized corrosion
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Galvanic Corrosion In PipeLine
Localized Corrosion InsideSteel Pipe Line
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Crevice Corrosion In PipeLine
Pitting Corrosion In Pipes
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q MIC MECHANISM
SRB Localized corrosion
Corrosion product Role of SRB King and Miller study
Corrosion rate of SRB is notless than 0.1mm/a
Other function of SRB
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MIC CORROSION PICTURES
MIC Corrosion In SteelPipe Sample
MIC Corrosion In SteelPipe Sample
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Corrosion Pictures
Sea Bed Sediment Corrosion In Marine Pipe
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MEASUREMENT OF METAL CORROSION RATE IN SBS
In situ measurementmethod
Laboratory method
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SBS CORROSION EVALUATION AND PREDICTION Based on weight loss
method
Models to evaluate andpredict corrosion
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CONCLUSION
Research on SBS corrosionis still in developing stage
Some problem need further study
Development in marineindustry demanding moreresearch on SBS corrosion
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REFERENCE
Batt c et al 2002 corros. Eng .sci .&technology.uk 37
Boussiba s 1989 plant cell physiol 30
Dinhhang t et al 2004 nature 427 Fischer k p 1981 mater .perf 20
Jack j r et al 1998 corrosion 54
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Thank You
Any Query?