Describe Passivation - ANSWER Passivation is the formation of a protective oxide film on
the surface reducing its chemical activity and its ability to corrode.
Describe the following factors and how they affect corrosion: - ANSWER • Oxygen: Oxy-
gen increases the rate of corrosion.
• Temperature: Corrosion usually accelerated with increasing temperature
• Chemical Salts: Increase the rate of corrosion by increasing the efficiency of the electro-
lyte.
• Humidity (or Wetness): The wetter the environment, the more corrosion is likely to occur.
• Pollutants and Acid Gases: Acid rain, chemical byproducts and chlorides all promote corro-
sion.
Two broad categories of corrosion can be described as: - ANSWER General
Localized
Describe Galvanic Corrosion - ANSWER Galvanic corrosion 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.
Describe Cathodic Protection - ANSWER Cathodic protection is the reduction or elimina-
tion of corrosion by making the structure to be protected a cathode by means of an im-
pressed current or attachment to a galvanic anode.
The two primary types of cathodic protection are: - ANSWER Impressed Current
Galvanic (Sacrificial)
1
,Impressed current power sources include: - ANSWER Rectified commercial power
Solar cells
Generators
Fuel cells
Wind-powered cells
Thermoelectric cells
Describe Cathodic Disbondment - ANSWER Cathodic disbondment is the separation of
the coating from the surface through hydroxyl (OH-) formation due to increased (made more
negative) potential.
The principal component of mild carbon steel is - ANSWER A. Iron (Fe)
The formation of a thin surface layer on metals, whether an oxide, carbonate, or other com-
pound, that slows the rate of the corrosion process is called? - ANSWER D. Passivation
Which is the part of a corrosion cell where metal dissolves? - ANSWER A. Anode
Which of these elements is likely to accelerate corrosion on a steel structure? - ANSWER
A. Salts
C. High temperatures
D. Pollutants
In a cathodic protection system the metal being protected is the? - ANSWER B. Cathode
When parts of a metal surface are shielded from full exposure to the environment because
of the close proximity of another metal, corrosion at that location is identified as? - AN-
SWER D. Crevice corrosion
2
,Cathodic protection using impressed current is most commonly used on? - ANSWER C.
Pipelines
Impressed current systems anodes include? - ANSWER A. Graphite
C. High silicon cast iron
Describe dehumidification: - ANSWER Dehumidification is the process of removing mois-
ture vapor from the air to lower its dew point.
When planning enclosures, the following minimum requirements should be considered: -
ANSWER • 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 in-
clement
weather.
• Have minimal leakage to maintain proper environmental conditions and ensure the dehu-
midification
system operates efficiently.
Describe air turns (air changes): - ANSWER • The air turnover principle eliminates air
stratification, or layering, in large open spaces by
recirculating the hot air that becomes trapped in the higher spaces
• The number of times it does this per hour is called air turns.
At and below what relative humidity does corrosion virtually cease? - ANSWER 0.4
Describe two ways to reduce the relative humidity of the boundary layer: - ANSWER • In-
crease the surface temperature
• Reduce moisture content by dehumidification.
3
, Types of dehumidification equipment include: - ANSWER • Refrigeration and desiccant
Describe several benefits of dehumidification: - ANSWER • 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.
You are the coating inspector on a project with dehumidification provided by a rotating bed
type dehumidifier. The silica gel has become contaminated. What do you expect to happen
with the silica gel? - ANSWER D. It can no longer adsorb moisture
What effect does the rotating bed dehumidifier have on the treated ambient air? - AN-
SWER B. It is heated and the humidity decreases
Some general basic centrifugal blast setups include: - ANSWER Tumbling Mill
Multi Table
Plain Table
Swing Table
Custom designed systems
Centrifugal blasting conveyor systems are commonly used for cleaning of: - ANSWER
Plate
Rolled structural shapes
Large trusses
Girders
Portable centrifugal blasting systems can be used on: - ANSWER Ship decks, hull sides,
and bottoms
Storage tanks
4
the surface reducing its chemical activity and its ability to corrode.
Describe the following factors and how they affect corrosion: - ANSWER • Oxygen: Oxy-
gen increases the rate of corrosion.
• Temperature: Corrosion usually accelerated with increasing temperature
• Chemical Salts: Increase the rate of corrosion by increasing the efficiency of the electro-
lyte.
• Humidity (or Wetness): The wetter the environment, the more corrosion is likely to occur.
• Pollutants and Acid Gases: Acid rain, chemical byproducts and chlorides all promote corro-
sion.
Two broad categories of corrosion can be described as: - ANSWER General
Localized
Describe Galvanic Corrosion - ANSWER Galvanic corrosion 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.
Describe Cathodic Protection - ANSWER Cathodic protection is the reduction or elimina-
tion of corrosion by making the structure to be protected a cathode by means of an im-
pressed current or attachment to a galvanic anode.
The two primary types of cathodic protection are: - ANSWER Impressed Current
Galvanic (Sacrificial)
1
,Impressed current power sources include: - ANSWER Rectified commercial power
Solar cells
Generators
Fuel cells
Wind-powered cells
Thermoelectric cells
Describe Cathodic Disbondment - ANSWER Cathodic disbondment is the separation of
the coating from the surface through hydroxyl (OH-) formation due to increased (made more
negative) potential.
The principal component of mild carbon steel is - ANSWER A. Iron (Fe)
The formation of a thin surface layer on metals, whether an oxide, carbonate, or other com-
pound, that slows the rate of the corrosion process is called? - ANSWER D. Passivation
Which is the part of a corrosion cell where metal dissolves? - ANSWER A. Anode
Which of these elements is likely to accelerate corrosion on a steel structure? - ANSWER
A. Salts
C. High temperatures
D. Pollutants
In a cathodic protection system the metal being protected is the? - ANSWER B. Cathode
When parts of a metal surface are shielded from full exposure to the environment because
of the close proximity of another metal, corrosion at that location is identified as? - AN-
SWER D. Crevice corrosion
2
,Cathodic protection using impressed current is most commonly used on? - ANSWER C.
Pipelines
Impressed current systems anodes include? - ANSWER A. Graphite
C. High silicon cast iron
Describe dehumidification: - ANSWER Dehumidification is the process of removing mois-
ture vapor from the air to lower its dew point.
When planning enclosures, the following minimum requirements should be considered: -
ANSWER • 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 in-
clement
weather.
• Have minimal leakage to maintain proper environmental conditions and ensure the dehu-
midification
system operates efficiently.
Describe air turns (air changes): - ANSWER • The air turnover principle eliminates air
stratification, or layering, in large open spaces by
recirculating the hot air that becomes trapped in the higher spaces
• The number of times it does this per hour is called air turns.
At and below what relative humidity does corrosion virtually cease? - ANSWER 0.4
Describe two ways to reduce the relative humidity of the boundary layer: - ANSWER • In-
crease the surface temperature
• Reduce moisture content by dehumidification.
3
, Types of dehumidification equipment include: - ANSWER • Refrigeration and desiccant
Describe several benefits of dehumidification: - ANSWER • 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.
You are the coating inspector on a project with dehumidification provided by a rotating bed
type dehumidifier. The silica gel has become contaminated. What do you expect to happen
with the silica gel? - ANSWER D. It can no longer adsorb moisture
What effect does the rotating bed dehumidifier have on the treated ambient air? - AN-
SWER B. It is heated and the humidity decreases
Some general basic centrifugal blast setups include: - ANSWER Tumbling Mill
Multi Table
Plain Table
Swing Table
Custom designed systems
Centrifugal blasting conveyor systems are commonly used for cleaning of: - ANSWER
Plate
Rolled structural shapes
Large trusses
Girders
Portable centrifugal blasting systems can be used on: - ANSWER Ship decks, hull sides,
and bottoms
Storage tanks
4
