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

MWEA Lagoon Seminar February 21, 2013 Identification & Mitigation of System Corrosion Nate Ver Heul

Definition cor·ro·sion [k uh -roh-zh uh n] noun The deterioration of a material or its properties because of a reaction with its environment.

Corrosion in Wastewater Systems • Bacterial • Electrochemical

Bacterial (H 2 S) Corrosion

Understanding…H 2 S Corrosion • Colorless, poisonous, flammable, explosive gas • Smells like rotten eggs • Desensitizer

Understanding…H 2 S Corrosion Health and Safety Impact of H 2 S H 2 S Level (ppm) Health Effects 0.0005 Noticeable smell 0-10 Irritation of eyes, nose and throat 10 Exposure limit H 2 S >10 ppm = Headache, dizziness, nausea, difficulty 10-50 concern for breathing system integrity Severe respiratory irritation, convulsions, 50-200 coma and possibly death

Understanding…H 2 S Corrosion • Sulfate is reduced to sulfide • Anaerobic digestion • Sulfide combines with Hydrogen to form H 2 S gas • H 2 S oxidates to Sulfuric Acid in presence of moisture

Facultative Lagoon

Understanding…H 2 S Corrosion

Understanding…H 2 S Corrosion • How do sulfates get into collection systems? • Sulfur cycle • Corrosion on the rise • Less heavy metals • Less inflow and infiltration

Identifying…H 2 S 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

Identifying...H 2 S Corrosion • Where to look • Headworks • Transfer Structures • Force Mains • Low velocities • Long detention times • Sections not flowing full • Air release manholes • Discharge manholes

Identifying…H 2 S Corrosion Pipe Inv. El. vs. HGL (1,000 gpm in force main) 630 625 620 Look out for 615 Elevation (ft) high points in 610 force mains 605 600 595 Pipe Inv El 590 HGL El 585 0 1000 2000 3000 4000 5000 6000 7000 8000 Distance from Lift Station (ft)

Identifying…H 2 S Corrosion Pipe Inv. El. vs. HGL (820 gpm in force main) 630 625 620 Look out for 615 Elevation (ft) high points in 610 force mains 605 600 595 Pipe Inv El 590 HGL El 585 0 1000 2000 3000 4000 5000 6000 7000 8000 Distance from Lift Station (ft)

Identifying…H 2 S 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

Identifying...H 2 S Corrosion • How to measure • Televising, Air Monitoring

Identifying…H 2 S Corrosion Panoramo MH Red Arrow Odalogger Viewer

Identifying…H 2 S Corrosion OdaLog Results Red Arrow Odalogger

Identifying…H 2 S Corrosion OdaLog Results

Mitigating…H 2 S Corrosion Coating/Lining

Mitigating…H 2 S Corrosion Polymer Concrete Manholes

Mitigating…H 2 S Corrosion Cured in place pipe

Mitigating…H 2 S Corrosion Chemical addition

Mitigating…H 2 S Corrosion Biofilters

Mitigating…H 2 S Corrosion Aeration

Mitigating…H 2 S Corrosion Electrical Sealoffs

Electrochemical Corrosion

Understanding…Electrochemical Corrosion • Return of Metals to their Ores • Dissipation of energy consumed by mining, refining and manufacturing

Understanding…Electrochemical Corrosion • Electrical potential • Anode • Cathode • Electrolyte • Solution of acids, bases or salts

Understanding…Electrochemical Corrosion Galvanic Series (Atlas Steel Technical Note No. 7 "Galvanic Corrosion“)

Understanding…Electrochemical Corrosion Iron Corrosion Schematic (chem1.com)

Identifying…Electrochemical Corrosion • What it looks like

Identifying…Electrochemical Corrosion • Where to look • Ferrous piping or tanks in aggressive soils • Pumping chambers • Above grade piping

Mitigating…Electrochemical Corrosion Cathodic protection - galvanic/ sacrificial anodes

Mitigating…Electrochemical Corrosion Cathodic protection - Impressed current

Mitigating…Electrochemical Corrosion Anodizing Galvanizing

Mitigating…Electrochemical Corrosion Isolation of dissimilar metals

Mitigating…Electrochemical Corrosion Polyethylene encasement

Recommendations • Know your system • Corrosion Detection and Monitoring Strategy • Maintain records • GIS • Maintenance procedures • Monitor potential problem areas regularly • Proper system design

Thank You