NACE CIP Level 2 Flashcards
__________ is the formation of a protective oxide film on the surface reducing its chemical activity and its ability to corrode.
Passivation
How does oxygen affect corrosion?
Oxygen increases the rate of corrosion.
How does temperature affect corrosion?
Corrosion is usually accelerated with increasing temperatures.
How does chemical salts affect corrosion?
Chemical salts increase the rate of corrosion by increasing the efficiency of the electrolyte.
How does humidity (or wetness) affect corrosion?
The wetter the environment, the more likely corrosion is to occur.
How does pollutants and acid gases affect corrosion?
Acid rain, chemical byproducts, and chlorides all promote corrosion.
What are two broad categories or corrosion described as?
Generalized
Localized
__________ is an electrochemical action of two dissimilar metals in the presence of an electrolyte and an electron conductive path, which occurs when dissimilar metals come into contact.
Galvanic corrosion
__________ is the reduction or elimination of corrosion by making the structure to be protected a cathode by means of an impressed current or attachment to a galvanic anode.
Cathodic protection
Impressed current power sources include:
Generators
Solar Cells
Rectified commercial power
Fuel cells
Thermoelectric cells
Wind-powered cells
__________ is the separation of the coating from the surface through hydroxyl (OH-) formation due to increased (made more negative) potential.
Cathodic disbondment
__________ is the process of removing moisture vapor from the air to lower its dew point.
Dehumidification
When planning enclosures, what minimum requirements should be considered?
Must be large enough to contain the whole work area.
Not be larger than the performance capabilities of the dehumidification equipment.
Be sturdy enough to hold up to intended work activities, potential loads, and possible inclement weather.
Have minimal leakage to maintain proper environmental conditions and ensure the dehumidification system operates efficiently.
What does the air turnover principle do?
Eliminates air stratification, or layering, in large open spaces by recirculating the hot air that becomes trapped in the higher spaces.
What is an “air turn” considered?
The number of times air turnover principle occurs per hour.
At what relative humidity does corrosion virtually cease?
At and below 40%.
What are two ways to reduce the relative humidity of the boundary layer?
Increase the surface temperature.
Reduce moisture content by dehumidification.
What are two types of dehumidification equipment?
Refrigeration
Desiccant
What are some benefits of dehumidification?
Dries the air.
Lowers the dew point.
Permits blasting the entire surface.
Holds the blast with dry air.
Helps in cleaning the surface.
Holds the surface during coating application.
What are some general basic centrifugal blast setups?
Tumbling mill
Multi table
Plan table
Swing Table
Custom designed systems
What are centrifugal blasting conveyor systems commonly used to clean?
Plate
Rolled structural shapes
Large trusses
Girders
What are portable centrifugal blasting systems used on?
Ship decks, hull sides, and bottoms
Storage tanks
Concrete floor
Highways and bridge decks
What elements generally compose a centrifugal blast system?
Centrifugal abrasive throwing wheel
The blast cabinet (or enclosure)
In fixed systems, some type of material handling system
Abrasive recycling system
A dust collector and vent-pipe system
Abrasives
What are some efficiency factors that centrifugal blast wheels depend on?
Abrasive operating mix
Size of the abrasive
Velocity of the abrasive coming off the wheel
Quantity and direction of the thrown abrasive
Condition of the feed parts