CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …
Transcript of CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …
![Page 1: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/1.jpg)
CLARIFYING MATERIAL SELECTION:
UNDERSTANDING THE CORROSION
MECHANISMS
FOR CLARIFIER MECHANISMS
DOUG SHERMAN, P.E. PRINCIPAL CONSULTANT, CORROSION PROBE, INC.
RANDY NIXON, PRINCIPAL CONSULTANT, CORROSION PROBE, INC.
WEAT Biosolids and Odor and Corrosion Conference
San Marcos, TX
August 5, 2015
![Page 2: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/2.jpg)
Presentation Outline
Introduction
Understanding the Corrosion Mechanisms
General Clarifier Environment
Materials and Their Specific Issues
Coated Steel
Hot-Dip Galvanized Steel
Stainless Steel
Other Materials Considerations
Galvanic Effects
Summary
![Page 3: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/3.jpg)
Introduction
![Page 4: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/4.jpg)
Understanding the Corrosion
Mechanisms
General Clarifier Environment (Immersion)
Corrosion of steel is mainly oxygen-driven
Generally < 10 mpy in aerated wastewater @ 100°F, pH 6 – 8
Stainless steel would not corrode
Where not aerated, acidic environs form
Under deposits, stagnant areas
Sulfide, other ions
Mircrobial reactions
![Page 5: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/5.jpg)
Understanding the Corrosion
Mechanisms
General Clarifier Environment (Immersion)
Corrosion Rates Affected by:
pH – normally 6 to 8; CO2 (covered tanks, bacterial metabolism)
Conductivity – sulfate, sulfide, chloride (coastal, ferric chloride)
Location
![Page 6: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/6.jpg)
Understanding the Corrosion
Mechanisms
Higher
Higher
Lower
Lower
![Page 7: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/7.jpg)
Understanding the Corrosion
Mechanisms
General Clarifier Environment (Immersion)
Corrosion Rates Affected by:
pH – normally 6 to 8; CO2 (covered tanks, bacterial metabolism)
Conductivity – sulfate, sulfide, chloride (coastal, ferric chloride)
Location
Differential cells (aeration, concentration) – potential differences
(anode/cathode)
![Page 8: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/8.jpg)
Understanding the Corrosion
Mechanisms
Above the Waterline
Weathering exposure, high humidity
Primary Clarifiers
Biogenic sulfide corrosion – biogenesis of H2S by SOB (covered
tanks)
Secondary Clarifiers
H2S and other sulfur species mostly gone
Oxygen-driven
![Page 9: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/9.jpg)
Materials and Their Specific Issues
Coated Steel
Organic resin-based
Epoxy
Polyurethane
Replaced coal-tar epoxy
Water, chemical resistance
Film build (12 to 30 mils/coat)
![Page 10: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/10.jpg)
Materials and Their Specific Issues
Coated Steel
Full epoxy below waterline
Epoxy/polyurethane above waterline
UV light resistance
Color/gloss retention
![Page 11: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/11.jpg)
Materials and Their Specific Issues
Coated Steel
Barrier protection
Minimize pinholes, discontinuities
Difficult in clarifiers: steel shapes
Angles, channel, flanged – edges, corners, etc.
![Page 12: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/12.jpg)
Materials and Their Specific Issues
![Page 13: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/13.jpg)
Materials and Their Specific Issues
Coated Steel
Barrier protection
Minimize pinholes, discontinuities
Difficult in clarifiers: steel shapes
Angles, channel, flanged – edges, corners, etc.
Proper selection, application
Edge retention
Film build/coat
“Stripe coating”
Attention to detail in shop and field
![Page 14: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/14.jpg)
Materials and Their Specific Issues
![Page 15: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/15.jpg)
Materials and Their Specific Issues
Coated Steel
Performance
15 to 18 years before major coating repair or recoating
Ongoing inspection, frequent repairs extend life to 30 years
Lower life-cycle cost
![Page 16: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/16.jpg)
Materials and Their Specific Issues
![Page 17: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/17.jpg)
Materials and Their Specific Issues
![Page 18: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/18.jpg)
Materials and Their Specific Issues
Hot-Dip Galvanized (HDG) Steel
Galvanic protection
Anodic to steel
Barrier coating
Atmospheric: zinc → zinc oxide → zinc hydroxide → zinc carbonate
Affected by moisture contact, rate of drying, exposure to
corrodents
“White rust”
Immersion: protective layer of calcium carbonate
![Page 19: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/19.jpg)
Materials and Their Specific Issues
HDG Steel
Corrosion of zinc in water depends on ability to form CaCO3 scale
hydrogen ion concentration (pH; 6 – 12)
total calcium content
total alkalinity
CaCO3 stability
Langelier Index
Ryznar Index
Practical Saturation Index
![Page 20: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/20.jpg)
Materials and Their Specific Issues
HDG Steel
Other factors
O2
CO2
TDS
Chloride
Temperature
Agitation
![Page 21: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/21.jpg)
Materials and Their Specific Issues
HDG Steel
4 – 6 mils, typ.
Pure Zn layer only 1.5 – 2
mils
When Zn-Fe layers exposed,
→ steel corrosion factors
Eta 100% Zn
Zeta 94% Zn 6% Fe
Delta 90% Zn 10% Fe
Gamma
75% Zn 25% Fe
Steel
![Page 22: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/22.jpg)
Materials and Their Specific Issues
![Page 23: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/23.jpg)
Materials and Their Specific Issues
![Page 24: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/24.jpg)
Materials and Their Specific Issues
![Page 25: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/25.jpg)
Materials and Their Specific Issues
Stainless Steel
Protective oxide film
Resists general corrosion
Susceptible to localized corrosion (pitting, crevice, MIC)
Threshold chloride concentration
PREN
![Page 26: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/26.jpg)
Materials and Their Specific Issues
Stainless Steel
Stainless
Steel Grade
UNS Number
Cr % (Typ.)
Mo % (Typ.) PREN1
Approx. Cl-
Concentration Below
Which Pitting does not Occur (ppm) 2
Relative
Cost (304 = 1.0)
304L S30403 18 0 18 300 1.00
316L S31603 17 2.1 23 1000 1.27
317LMN S31726 18.5 4.1 32 5000 2.28
2205 S32205 22.5 3.3 34 5000 1.24
AL6XN N08367 20.5 6.1 43 Seawater 3.66
1 PREN = Pitting Resistance Equivalent Number; %Cr + 3.3·%Mo + 16·%N, based on minimum composition 2 At 95°F, neutral pH
![Page 27: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/27.jpg)
Materials and Their Specific Issues
Stainless Steel
Fabrication issues
Welds
![Page 28: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/28.jpg)
Materials and Their Specific Issues
![Page 29: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/29.jpg)
Materials and Their Specific Issues
![Page 30: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/30.jpg)
Materials and Their Specific Issues
Stainless Steel
Fabrication issues
Surface finish
![Page 31: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/31.jpg)
Materials and Their Specific Issues
![Page 32: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/32.jpg)
Materials and Their Specific Issues
Stainless Steel
Fabrication issues
Crevices
![Page 33: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/33.jpg)
Materials and Their Specific Issues
![Page 34: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/34.jpg)
Materials and Their Specific Issues
Stainless Steel
Process conditions
Wet/dry cycles
![Page 35: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/35.jpg)
Materials and Their Specific Issues
![Page 36: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/36.jpg)
Materials and Their Specific Issues
![Page 37: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/37.jpg)
Materials and Their Specific Issues
Stainless Steel
Process conditions
Microbial action
Stagnant conditions (< 5 ft/s)
![Page 38: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/38.jpg)
Materials and Their Specific Issues
![Page 39: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/39.jpg)
Materials and Their Specific Issues
![Page 40: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/40.jpg)
Materials and Their Specific Issues Stainless Steel
Stainless
Steel Grade
UNS Number
Cr % (Typ.)
Mo % (Typ.) PREN1
Approx. Cl-
Concentration Below
Which Pitting does not Occur (ppm) 2
Relative
Cost (304 = 1.0)
304L S30403 18 0 18 300 1.00
316L S31603 17 2.1 23 1000 1.27
317LMN S31726 18.5 4.1 32 5000 2.28
2205 S32205 22.5 3.3 34 5000 1.24
AL6XN N08367 20.5 6.1 43 Seawater 3.66
1 PREN = Pitting Resistance Equivalent Number; %Cr + 3.3·%Mo + 16·%N, based on minimum composition 2 At 95°F, neutral pH
![Page 41: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/41.jpg)
Materials and Their Specific Issues
Other Materials Considerations
Galvanic effects
![Page 42: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/42.jpg)
Materials and Their Specific Issues
![Page 43: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/43.jpg)
Summary
For New or Rehab Design, Must Understand:
Operating environment(s)
Candidate materials and their properties
Damage mechanisms caused by interactions between them
Fabrication and erection practices and effects on corrosion
resistance
Coated Steel
Viable
Inspection and maintenance
![Page 44: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/44.jpg)
Summary
HDG Steel
High susceptibility for failure in many WW environs
Metallic → more issues than organic coatings
Inspection and maintenance
Cannot be replaced
Stainless Steel
Step above in most cases
Higher initial material costs offset by lower inspection and repair costs
Can have issues ($$) if not chosen properly
![Page 45: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/45.jpg)
Summary
Any Material Requires:
Tight and enforceable material/fabrication spec
Good QA/QC during fabrication and erection
![Page 46: CLARIFYING MATERIAL SELECTION: UNDERSTANDING THE …](https://reader031.fdocuments.net/reader031/viewer/2022012517/6190e9bdb872d53494725ad9/html5/thumbnails/46.jpg)
Questions?