Term
| Types of Corrosive Atmospheres |
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Definition
*Industrial
*Marine
*Rural
*Indoor |
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Term
| Characterized by pollution composed mainly of sulfur & nitrogen oxides |
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Definition
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Term
| Laden with sea-salt (chlorides such as NaCl) |
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Definition
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Term
| Contains organic & inorganic dusts |
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Definition
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Term
*No typical contaminant or set of conditions
*Can contain mild or severe fumes |
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Definition
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Term
| The ratio of the quantity of water vapor present in the atmosphere to the saturation quantity at a given temperature |
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Definition
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Term
| 60% is critical for iron without pollutants |
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Definition
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Term
| Lower % when pollutants are present |
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Definition
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Term
| ___ ___calculated from RH data |
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Definition
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Term
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Definition
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Term
*Physical configuration of the system
*Chemistry of the water
*Presence of solids in the water
*Flow rate
*Temperature of the water
*Presence of bacteria |
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Definition
| Factors Influencing Water System Corrosion |
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Term
| Most corrosion damage to equipment & structures occurs in the ___, as opposed to liquid immersion. |
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Definition
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Term
| Laden w/ fine particles of sea-salt mist carried by the wind to settle on exposed surfaces. |
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Definition
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Term
| Its principal corrosive constituent is moisture and gaseous elements such as oxygen and carbon dioxide. |
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Definition
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Term
| Most important factor in atmospheric corrosion, overriding pollution or lack of it, is ___, either in the form of rain, dew, condensation, or high relative humidity. |
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Definition
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Term
| In the absence of ____, most contaminants have little or no corrosive effect. |
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Definition
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Term
| what are the 2 ways that Temp. play an important role in atmospheric corrosion |
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Definition
*The normal increase in corrosion activity
*Temperature lag of metallic objects, bc of their heat capacity, behind changes in the ambient temp |
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Term
| Dispersion of a liquid in a gas or a solid in a gas |
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Definition
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Term
*Produced by ejection into the atmosphere:
*Sea spray
*Wind-blown dust |
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Definition
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Term
Produced by physical and chemical processes within the atmosphere:
*Atmospheric gases reacting and condensing
*Cooling vapor condensation |
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Definition
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Term
*Product of combustion of fuels (coal, diesel, gas)
*Produces sulfuric acid |
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Definition
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Term
*Product of combustion (vehicle exhaust fumes)
*Produces nitric acid |
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Definition
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Term
*SO2 + NOx + Aerosol particles react with moisture & UV light
*50% of haze is a combination of sulfuric & nitric acids |
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Definition
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Term
Sulfur Dioxide
Nitrogen Oxides
Haze or SMOG |
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Definition
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Term
| The ___ refers to the period of time during which the atmospheric conditions are favorable for the formation of a surface layer of moisture on a metal or alloy. |
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Definition
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Term
*Relative humidity greater than 80%
*Temperature greater than 00C |
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Definition
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Term
| is measured with special sensors that can be tailored to measure the presence of moisture such as precipitation, condensation or splash, which forms a conductive path between the sensor elements. |
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Definition
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Term
| are interlaced on a thin, nonconductive substrate |
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Definition
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Term
| When moisture condenses the ___, it activates the cell, producing a small voltage across the resistor. |
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Definition
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Term
| Not corrosive without dissolved gases or pollutants |
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Definition
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Term
(PURE WATER)
*Oxygen
*Carbon dioxide
*Nitrogen
*Ammonia
*Sulfurous gases |
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Definition
| Corrosive dissolved gases |
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Term
Chlorides
Calcium (Mild)
Sulfides
Mineral deposits
Acids
Metal ions |
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Definition
| Corrosive Constituents in Water (excluding Gases) |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
| refers to the content of gaseous and suspended salt in the atmosphere |
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Definition
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Term
| is measured in μg/m3 (Airborne Chlorides) |
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Definition
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Term
| is measured in mg/m2/day (Airborne Chlorides) |
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Definition
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Term
| Measured by the wet candle method |
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Definition
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Term
| Measures atmospheric chloride deposition (amount of chloride salts deposited from the atmosphere on a given area per unit time). |
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Definition
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Term
| The simplest form of direct atmospheric-corrosion measurement is by ___ exposures. |
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Definition
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Term
| ___ coupon measurements have extremely long exposure times |
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Definition
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Term
| ____ coupons are more sensitive and reduce exposure time |
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Definition
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Term
*Measurement of Corrosion:
-Loss in weight or reduction in thickness/time
-Change in tensile strength
Time to fracture (SCC) |
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Definition
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Term
*Accelerated Tests:
---Salt spray test
---Wet-dry mixed salt-spray tests
---High-chloride cyclic salt-spray tests |
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Definition
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Term
| The use of bimetallic specimens in which a helical wire is wrapped around a coarsely threaded bolt. |
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Definition
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Term
Relative Corrosion Rates in the Atmosphere:
--Carbon Steel |
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Definition
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Term
Relative Corrosion Rates in the Atmosphere:
--Cast Iron |
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Definition
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Term
Relative Corrosion Rates in the Atmosphere:
--copper |
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Definition
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Term
Relative Corrosion Rates in the Atmosphere:
--zinc |
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Definition
| Low, except around acid fumes or when coupled |
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Term
Relative Corrosion Rates in the Atmosphere:
--aluminum |
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Definition
| Low, except when coupled or copper alloyed |
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Term
Relative Corrosion Rates in the Atmosphere:
--stainless steel |
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Definition
| Low, except some alloys will pit if chlorides are present |
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Term
*Oxygen, ozone, and moisture act with sunlight to degrade plastics:
--Continued polymerization
--Crystallization
--Evaporation of plasticizer
--Oxidation of polymer chains |
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Definition
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Term
*Indications of damage
--Blushing
--Chalking
--Color Change |
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Definition
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Term
| Atmospheric Corrosion Prevention |
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Definition
*Protective Coatings (Most common)
*Material Selection:
--Protective Scale Properties
--Low Energy Materials
*Control of the Atmosphere |
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Term
-is the most widely used)
-pH effect on CaCO3 saturation (scaling index) |
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Definition
| Langelier Saturation Index (LSI) |
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Term
| -CaCO3 thickness and stability in municipal water systems (scaling index) |
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Definition
| Ryznar Stability Index (RSI) |
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Term
| -buffering capacity of water incorporated (scaling index) |
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Definition
| Puckorius Scaling Index (PSI) |
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Term
| Great Lakes water (scaling index) |
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Definition
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Term
| CO2 and pH effects + phases correction (scaling index) |
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Definition
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Term
| Common ion effect correction (scaling index) |
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Definition
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Term
| Tests used to indirectly measure the organic compounds in water. |
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Definition
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Term
| Used for sludge studies, pollution, & other chemical analysis of sewage and industrial waste plant efficiencies |
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Definition
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Term
| Most applications of COD determine the amount of organic pollutants found in surface waters (e.g. lakes and rivers), making COD a useful measure of water quality. |
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Definition
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Term
| The BOD value indicates the amount of oxygen in water needed for ____ ___ of organic compounds dissolved in wastewater. |
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Definition
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Term
| For BOD determination, ____ are added to the water sample. After a predefined time interval, usually 5 days, the oxygen consumed by bacteria during decomposition of organic compounds in the water sample is determined. |
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Definition
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Term
*Soil Conductivity (µS/cm)
*Soil Resistivity (Ohm-cm)
*Other key factors in Soil |
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Definition
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Term
*Ions and moisture lower the resistivity:
--1,000 ohm-cm is very low
--5,000 ohm-cm is average
--10,000 ohm-cm is very high |
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Definition
| Soil Resistivity (Ohm-cm) |
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Term
| Other key factors in Soil |
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Definition
*Oxygen
*pH
*Variety of Corrosion Cells |
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Term
| Concentration cells (corrosion cells in soils) |
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Definition
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Term
Galvanic cells
Temperature cells
Surface-Film cells
Resistivity / Conductivity changes |
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Definition
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Term
Soil changes
Oxygen access
Pipe impurities
Cold bends, stresses
Weld effects
Stray current
Biological Organisms
Others |
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Definition
Pipe-Line Corrosion
(corrosion cells in soil) |
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Term
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Definition
Gases at the anode
Gases at the cathode |
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Term
Oxygen
Chlorine
Carbon monoxide
Carbon dioxide
Local acidity |
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Definition
Gases at the anode
(effects of CP in soil) |
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Term
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Definition
Gases at the cathode
(effects of CP in soil) |
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Term
Electro-endosmosis
Cathode scale
Dis-bonding
Interference |
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Definition
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Term
| use of bimetallic specimens inwhich a helical wire is wrappped around a coarsely threaded bolt |
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Definition
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Term
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Definition
1. pH control
2. scale inhibitors
3. Remove scales |
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Term
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Definition
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Term
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Definition
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Term
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Definition
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Term
*once thru systems
*re-circulated systems:
--closed systems
--open systems |
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Definition
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Term
*corrosion inhibition
*scale control
*microorganisms control
*silt control
*foaming, emulsions, density control |
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Definition
| reasons for water treatment |
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Term
Deposition
Oxygen exclusion
Feedwater makeup
Corrosion products
Bacteria
Shut-down problems
Special alloys |
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Definition
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Term
| copper plating on turbine blades, silica plating, metal ions |
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Definition
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Term
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Definition
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Term
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Definition
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Term
| slime, acids, H2S production |
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Definition
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Term
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Definition
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Term
| current flows in what direction |
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Definition
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Term
| anywhere where current collets ( ___ ) is going to be protected |
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Definition
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Term
| coldside becomes cathode/anode? (temp.cells) |
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Definition
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Term
| area of high temp. anode/cathode? |
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Definition
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Term
| hydrogen gas at the anode/cathode |
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Definition
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Term
| a copper wire line is electrically coupled to a cast iron water main. The copper water line is the anode/cathode? |
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Definition
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Term
| get another metal that is more negative to become the new anode, making the old old anode a cathode. |
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Definition
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Term
*pipeline bends
*cold work from mishandling
*fabrication stresses
*sharp rocks
*expansion & contraction |
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Definition
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Term
| is mill scale cathodic/anodic to steel |
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Definition
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Term
Reduces the CP current requirement
May shield CP if adhesion is inadequate
Holidays may cause local cells before CP
Coating must be compatible with CP
Over protection may damage coatings |
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Definition
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Term
Resistivity survey
Potential survey (Annual & CIS)
pH survey
Coating evaluation surveys |
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Definition
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Term
DCVG
ACVG
Pearson
Conductance testing |
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Definition
| Coating evaluation surveys |
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Term
Distribution systems
Gathering systems
Plant piping
Well casings
UST’s, AST’s
Steel piling
Towers, Footings, Grounds |
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Definition
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Term
Cast iron
Aluminum
Zinc
Lead
Stainless Steel
Copper
Concrete
Polymeric
--PVC, ABS, PE
--Fiberglass |
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Definition
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