Objective 02: Environmental Effect on Corrosion

Question 1

Environment (Corrosion)

Answer 1

The direct and intimate surroundings of a material, which expose the material to substances or conditions that have the potential to interact chemically with the material

Question 2

What are the 2 general environments that must be considered in controlling corrosion?

Answer 2

1. External, natural environment

2. Internal environment

Question 3

What characterizes the Internal Environment for a particular plant?

Answer 3

The unique processes, fluids, and materials inside the piping, vessels, and equipment

Question 4

What are the 3 subdivisions of the External Environment?

Answer 4

1. Air
2. Water
3. Soil

Question 5

What largely affects the quality of the air around a facility?

Answer 5

Adjacent geography and land use

Question 6

What are the 6 categories of common atmospheric influences on External Environment Corrosion at a facility?

Answer 6

1. Industrial or urban surroundings
2. Rural surroudings
3. Coastal location
4. High humidity and wet climate
5. High temperature
6. Excessive sunlight and other radiation

Question 7

How can industrial or urban surroundings contribute to external corrosion?

Answer 7

Nearby industry emissions and urban pollution may cause acid rain

Question 8

How can rural surroudings contribute to external corrosion?

Answer 8

There may be corrosive contaminants in the air due to fertilizers and ammonia

Question 9

How can coastal location surroudings contribute to external corrosion?

Answer 9

Salt water is more corrosive than fresh water and mist from a body of salt water can be very corrosive to the external coverings on vessels, piping, and buildings

Question 10

How can high humidity and wet climate surroudings contribute to external corrosion?

Answer 10

Moisture in the air is corrosive and rain can capture corrosive products, i.e. acid rain

Question 11

How can high temperature surroudings contribute to external corrosion?

Answer 11

Corrosion rates generally increase as temperature increases, unless the air is very dry

Question 12

How does excessive sunlight and other radiation surroudings contribute to external corrosion?

Answer 12

Radiation encourages corrosive elements in the environment to become active

Question 13

What determiness the nature of the water in the External Environment?

Answer 13

The location of the facility in relation to common sources, e.g. lakes, rivers, oceans, and underground wells

Question 14

What must be considered with respect to water from the External Environment and corrosion?

Answer 14

Contaminants in the water may cause direct corrosion or form deposits which may encourage other corrosion mechanisms

Question 15

What are the most common corrosion-enhancing contaminants in water?

Answer 15

1. Dissolved gases, e.g. oxygen, carbon dioxide, and methane
2. Dissolved solids
3. Biological micro-organisms

Question 16

How do dissolved solids in water encourage corrosion?

Answer 16

They can interfere with corrosion inhibiting chemicals and increase the water’s electrical conductivity which strengthens corrosion cells

Question 17

How can dissolved gases in water encourage corrosion?

Answer 17

They can encourag pitting and acid formation

Question 18

How can micro-organisms in water encourage corrosion?

Answer 18

They can contribute to under-deposit corrosion and enhance oxygen generation

Question 19

What must be considered for soil from the External Environment and corrosion?

Answer 19

The nature and variations of the soil within a facility and the interaction of the process with the soil can affect the corrosion of foundations and underground piping or vessels.

Question 20

What 6 factors cause soil corrosion to increase?

Answer 20

1. Moisture content
2. Oxygen content
3. Electrical conductivity
4. Acidity
5. Dissolved salts
6. Sulfate-reducing anaerobic bacteria