Cathodic Protection in Materials Techniques Engineering

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What is the purpose of the continuous current source in the impressed current cathodic protection method?

To create a potential difference between the metal body and the ground bed
To convert the alternating current source into a direct current (correct)
To provide a steady flow of current to the metal body being protected
To control the amount of current being applied to the system

What is the purpose of the ground bed in the impressed current cathodic protection method?

To provide a source of current for the metal body being protected
To provide a path for the current to flow from the metal body to the ground
To control the amount of current being applied to the system
To act as the positive end of the current source (correct)

What is the purpose of burying the anodes in coke breeze backfill in the impressed current cathodic protection method?

To increase the surface area of the anodes
To control the amount of current being applied to the system
To provide a source of current for the metal body being protected
To reduce the anode-soil contact resistance (correct)

What is the purpose of using shallow ground beds in the impressed current cathodic protection method?

To provide a path for the current to flow from the metal body to the ground (D) Signup and view all the answers

What is the purpose of using vertical ground beds in the impressed current cathodic protection method?

To reach the soil layers of low resistance (D) Signup and view all the answers

What is the purpose of the whole structure being at one potential in cathodic protection?

To eliminate the need for anode and cathode sites (A) Signup and view all the answers

What is the purpose of digging deep wells of the closed type in areas with very high specific resistance?

To reach the lower layers with small specific resistance (C) Signup and view all the answers

What material is commonly used for sacrificial anodes in cathodic protection systems?

Magnesium (A) Signup and view all the answers

What role does the sacrificial anode play in a cathodic protection system?

It corrodes sacrificially to protect the structure (B) Signup and view all the answers

Why is a metallic connection installed between the sacrificial anode and the structure in a cathodic protection system?

To create a return current path for electrons (A) Signup and view all the answers

In order for the sacrificial anode method to work, what two other conditions must exist besides the anode and cathode?

A return current path and an electrolyte (D) Signup and view all the answers

What does Step 1 of designing an Impressed Current Cathodic Protection System involve?

Reviewing soil resistivity (B) Signup and view all the answers

What is the primary purpose of Step 1 in the design process?

To determine the current requirement for the cathodic protection system (B) Signup and view all the answers

Which step involves calculating the number of anodes needed to satisfy the manufacturer's current density limitations?

Step 4 (B) Signup and view all the answers

What variable represents the recommended maximum current density output in the equation given in Step 4?

I1 (B) Signup and view all the answers

In the equation given in Step 5, what does the variable 'n' represent?

The design life in years (B) Signup and view all the answers

Which variable in the equation given in Step 6 represents the soil resistivity?

p (B) Signup and view all the answers

According to Step 7, what determines the final number of anodes to be used in the design?

The highest number calculated from Steps 4, 5, and 6 (B) Signup and view all the answers

What is the first step in designing a galvanic cathodic protection system?

Review soil resistivity (D) Signup and view all the answers

Which equation is used to calculate the anode groundbed resistance in an impressed current cathodic protection system design?

Ra = ρ / (2πr) (D) Signup and view all the answers

What is the purpose of calculating the total circuit resistance in an impressed current cathodic protection system design?

To calculate the rectifier size needed (B) Signup and view all the answers

Which step in the galvanic cathodic protection system design involves selecting the number of anodes to be used?

Step 6 (C) Signup and view all the answers

What is the purpose of calculating the groundbed header cable resistance in an impressed current cathodic protection system design?

To calculate the total circuit resistance (B) Signup and view all the answers

Which step in the impressed current cathodic protection system design involves preparing plans and specifications?

Step 13 (A) Signup and view all the answers

What is the primary purpose of cathodic protection?

To control the corrosion of a metal surface by making it the cathode (D) Signup and view all the answers

How does cathodic protection work to reduce corrosion?

By applying an external current to the metal to be protected (A) Signup and view all the answers

What is the relationship between the electric current and the corrosion rate in a metal?

The higher the electric current, the greater the corrosion rate (A) Signup and view all the answers

What is the key principle behind cathodic protection?

Reducing the difference in potential between the anode and cathode (D) Signup and view all the answers

What is the primary way that cathodic protection is applied to a structure?

By applying a current to the structure from an outside source (B) Signup and view all the answers