Identification & Mitigation of System Corrosion Nate Ver Heul - - PowerPoint PPT Presentation

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Identification & Mitigation of System Corrosion Nate Ver Heul - - PowerPoint PPT Presentation

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MWEA Lagoon Seminar February 21, 2013 Identification & Mitigation of System Corrosion Nate Ver Heul Definition corrosion [k uh -roh-zh uh n] noun The deterioration of a material or its properties because of a reaction with its

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Identification & Mitigation of System Corrosion

Nate Ver Heul

MWEA Lagoon Seminar February 21, 2013

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Definition

cor·ro·sion [kuh-roh-zhuh n] noun

The deterioration of a material or its properties because of a reaction with its environment.

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  • Bacterial
  • Electrochemical

Corrosion in Wastewater Systems

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Bacterial (H2S) Corrosion

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Understanding…H2S Corrosion

  • Colorless, poisonous,

flammable, explosive gas

  • Smells like rotten eggs
  • Desensitizer
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H2S >10 ppm = concern for system integrity

Understanding…H2S Corrosion

Health and Safety Impact of H2S H2S Level (ppm) Health Effects 0.0005 Noticeable smell 0-10 Irritation of eyes, nose and throat 10 Exposure limit 10-50 Headache, dizziness, nausea, difficulty breathing 50-200 Severe respiratory irritation, convulsions, coma and possibly death

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Understanding…H2S Corrosion

  • Sulfate is reduced to sulfide
  • Anaerobic digestion
  • Sulfide combines with Hydrogen

to form H2S gas

  • H2S oxidates to Sulfuric Acid in

presence of moisture

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SLIDE 8

Facultative Lagoon

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Understanding…H2S Corrosion

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Understanding…H2S Corrosion

  • How do sulfates get into

collection systems?

  • Sulfur cycle
  • Corrosion on the rise
  • Less heavy metals
  • Less inflow and infiltration
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Identifying…H2S Corrosion

  • What it looks like/Potential

signs

  • Blackened wastewater or

sludge

  • Concrete
  • Cement is attacked – soft,

easily crumbles

  • Reinforcing steel – rust

bleeding

  • Ferrous Piping, internal and

external

  • Pitting, discoloration
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Identifying...H2S Corrosion

  • Where to look
  • Headworks
  • Transfer Structures
  • Force Mains
  • Low velocities
  • Long detention times
  • Sections not flowing full
  • Air release manholes
  • Discharge manholes
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Look out for high points in force mains

Identifying…H2S Corrosion

585 590 595 600 605 610 615 620 625 630 1000 2000 3000 4000 5000 6000 7000 8000

Elevation (ft) Distance from Lift Station (ft)

Pipe Inv. El. vs. HGL (1,000 gpm in force main)

Pipe Inv El HGL El

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SLIDE 14

Look out for high points in force mains

Identifying…H2S Corrosion

585 590 595 600 605 610 615 620 625 630 1000 2000 3000 4000 5000 6000 7000 8000

Elevation (ft) Distance from Lift Station (ft)

Pipe Inv. El. vs. HGL (820 gpm in force main)

Pipe Inv El HGL El

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Identifying…H2S Corrosion

  • Where to look
  • Underdeveloped/Oversized

Lift station wet wells

  • Sewers
  • Lines with minimal flow
  • Long, flat sewers
  • Turbulence
  • Transition and drop manholes
  • Pipe slope changes
  • Downstream of Industries
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Identifying...H2S Corrosion

  • How to measure
  • Televising, Air Monitoring
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Panoramo MH Viewer

Identifying…H2S Corrosion

Red Arrow Odalogger

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OdaLog Results

Identifying…H2S Corrosion

Red Arrow Odalogger

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OdaLog Results

Identifying…H2S Corrosion

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Coating/Lining

Mitigating…H2S Corrosion

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Polymer Concrete Manholes

Mitigating…H2S Corrosion

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Cured in place pipe

Mitigating…H2S Corrosion

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Chemical addition

Mitigating…H2S Corrosion

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Biofilters

Mitigating…H2S Corrosion

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Aeration

Mitigating…H2S Corrosion

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Electrical Sealoffs

Mitigating…H2S Corrosion

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Electrochemical Corrosion

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Understanding…Electrochemical Corrosion

  • Return of Metals to their Ores
  • Dissipation of energy consumed

by mining, refining and manufacturing

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Understanding…Electrochemical Corrosion

  • Electrical potential
  • Anode
  • Cathode
  • Electrolyte
  • Solution of acids,

bases or salts

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Galvanic Series

(Atlas Steel Technical Note No. 7 "Galvanic Corrosion“)

Understanding…Electrochemical Corrosion

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Iron Corrosion Schematic (chem1.com)

Understanding…Electrochemical Corrosion

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Identifying…Electrochemical Corrosion

  • What it looks like
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Identifying…Electrochemical Corrosion

  • Where to look
  • Ferrous piping or tanks in

aggressive soils

  • Pumping chambers
  • Above grade piping
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Cathodic protection

  • galvanic/

sacrificial anodes

Mitigating…Electrochemical Corrosion

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Cathodic protection

  • Impressed

current

Mitigating…Electrochemical Corrosion

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Anodizing Galvanizing

Mitigating…Electrochemical Corrosion

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Isolation of dissimilar metals

Mitigating…Electrochemical Corrosion

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Polyethylene encasement

Mitigating…Electrochemical Corrosion

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Recommendations

  • Know your system
  • Corrosion Detection and

Monitoring Strategy

  • Maintain records
  • GIS
  • Maintenance procedures
  • Monitor potential problem

areas regularly

  • Proper system design
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Thank You