Corrosion In Soils

Corrosion in Soils Raymond F. Mignogna, MS, PE Metallurgical Engineer

ECONOMICS OF CORROSION ,[object Object],[object Object],[object Object]

THE SOIL CORROSION PROBLEM ,[object Object]

ISSUES RELEVANT TO SOIL CORROSION ,[object Object],[object Object],[object Object],[object Object],[object Object]

OUTLINE ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Affected Facilities ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Corrosion Damage ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Factors Affecting the Corrosion Process ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Aeration More Air = Less Corrosion Drier Environment Reduces Galvanic Action ,[object Object],[object Object],[object Object],[object Object]

Water Retention More Water = More Electrolyte = More Corrosion

Dissolved Salt Content More Dissolved Salt = Higher Conductivity Higher Conductivity = Greater Corrosivity

Soil Resistivity ,[object Object],[object Object]

Resistivity vs Corrosivity ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Soil Acidity ,[object Object],[object Object],[object Object],[object Object],[object Object]

Ionic Species and Microbes ,[object Object]

Active Bacteria are fed by Sulfate Ions (SO4-) ,[object Object],[object Object],[object Object],[object Object],[object Object]

Corrosion Mechanism ,[object Object],[object Object]

Galvanic Corrosion ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Copper (V = -.2) Zinc (V = -1.1) Dissimilar Metal Corrosion in Neutral Soils and Water Cathode Anode Ion Flow

CHEMICAL REACTION ,[object Object],[object Object]

Electric Current Flow Ionic Current Flow Anode Cathode SOIL Corrosion Cell on Buried Metal Surface Poor Aeration Region Good Aeration Region

Stray-Current Corrosion ,[object Object],[object Object],[object Object],[object Object],[object Object]

Corrosion Control ,[object Object],[object Object]

Impressed Current Protection ,[object Object],[object Object],[object Object],Anode Cathode

Structure (cathode) Anode Power Supply + - i GROUND AIR

SOIL Structure (Steel) Anode (Zn or Mg)* Wire SACRIFICIAL ANODE Ion Flow * Zn = Zinc; Mg = Magnesium

ANODE PLACEMENT ,[object Object],[object Object],[object Object]

Modern Practice ,[object Object],[object Object],[object Object]

SUMMARY WHAT WE’VE DISCUSSED ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

REFERENCES ,[object Object],[object Object],[object Object]

QUESTIONS? COMMENTS? NEED MORE INFORMATION? Please email me at [email_address] or visit www.mignogna.net

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