API RP 571 3.8 Atmospheric Corrosion
Final Exam Version 1 Questions And
Accurate Answers.
3.8.1 Description of Damage - correct answers Corrosion that occurs from moisture associated with
atmospheric conditions. Marine environments and moist, polluted industrial environments with
airborne contaminants are the most severe. Dry rural environments cause very little corrosion.
3.8.2 Affected Materials - correct answers Carbon steel, low-alloy steels, and copper alloyed aluminum.
3.8.3 Critical Factors - correct answers a) The physical location of the plant (industrial, marine, urban,
rural).
b) The amount of moisture (humidity, rainfall) typically present or the presence of cooling tower mist.
c) The presence of salts, sulfur compounds, dirt, or other contaminants in the air.
d) Chlorides, H2S, fly ash, and other airborne contaminants from cooling tower and wet gas scrubber
drift, furnace stacks, and other equipment accelerate corrosion.
e) Orientation to the prevailing wind and rain.
f) Corrosion rates increase with temperature up to about 250°F (120°C). Above 250°F (120°C), surfaces
are usually too dry for corrosion to occur except under insulation. (See 3.22)
g) Designs that trap water or moisture in crevices or other configurations are more prone to attack.
h) Marine environments can be very corrosive (about 20 mpy) as are industrial environments that
contain acids or sulfur compounds that can form acids (about 5mpy to 10mpy).
i) Inland locations exposed to a moderate amount of precipitation or humidity are considered
moderately corrosive environments (about 1mpy to 3mpy).
j) Dry rural environments usually have verylow corrosion rates (<1mpy).
k) Bird droppings can also cause accelerated corrosion and unsightly stains.
3.8.4 Affected Units or Equipment - correct answers a) Unpainted, uninsulated carbon steel and low-
alloy steel piping and equipment operating below 250°F (120°C) where moisture can contact the
surface.
Final Exam Version 1 Questions And
Accurate Answers.
3.8.1 Description of Damage - correct answers Corrosion that occurs from moisture associated with
atmospheric conditions. Marine environments and moist, polluted industrial environments with
airborne contaminants are the most severe. Dry rural environments cause very little corrosion.
3.8.2 Affected Materials - correct answers Carbon steel, low-alloy steels, and copper alloyed aluminum.
3.8.3 Critical Factors - correct answers a) The physical location of the plant (industrial, marine, urban,
rural).
b) The amount of moisture (humidity, rainfall) typically present or the presence of cooling tower mist.
c) The presence of salts, sulfur compounds, dirt, or other contaminants in the air.
d) Chlorides, H2S, fly ash, and other airborne contaminants from cooling tower and wet gas scrubber
drift, furnace stacks, and other equipment accelerate corrosion.
e) Orientation to the prevailing wind and rain.
f) Corrosion rates increase with temperature up to about 250°F (120°C). Above 250°F (120°C), surfaces
are usually too dry for corrosion to occur except under insulation. (See 3.22)
g) Designs that trap water or moisture in crevices or other configurations are more prone to attack.
h) Marine environments can be very corrosive (about 20 mpy) as are industrial environments that
contain acids or sulfur compounds that can form acids (about 5mpy to 10mpy).
i) Inland locations exposed to a moderate amount of precipitation or humidity are considered
moderately corrosive environments (about 1mpy to 3mpy).
j) Dry rural environments usually have verylow corrosion rates (<1mpy).
k) Bird droppings can also cause accelerated corrosion and unsightly stains.
3.8.4 Affected Units or Equipment - correct answers a) Unpainted, uninsulated carbon steel and low-
alloy steel piping and equipment operating below 250°F (120°C) where moisture can contact the
surface.
