CP3 – Cathodic Protection Technologist
Certification Exam
1. The primary purpose of a cathodic protection survey is to:
A. Determine soil composition
B. Verify protective potentials on the structure
C. Measure pipe diameter
D. Inspect coating color
Answer: B
Explanation: CP surveys confirm that structure potentials are within protective criteria.
2. The most commonly used reference electrode for buried pipelines is:
A. Ag/AgCl
B. Cu/CuSO₄
C. Hg/HgSO₄
D. Zn/ZnSO₄
Answer: B
Explanation: Cu/CuSO₄ reference electrodes are standard for soil environments.
3. IR drop error in CP measurements is caused by:
A. Poor coatings only
B. Resistance in the electrolyte between structure and reference electrode
C. Voltage fluctuations in rectifiers
D. Soil temperature changes
Answer: B
Explanation: IR drop occurs due to current flowing through the soil resistance.
4. The most accurate potential measurement is obtained using:
A. Instant-OFF potential
B. ON potential
C. AC potential
D. Native potential
Answer: A
Explanation: Instant-OFF eliminates IR drop, giving accurate polarization levels.
,5. In CP systems, ‘polarization’ refers to:
A. Change in rectifier voltage
B. Shift in structure’s potential due to CP
C. Temperature rise in soil
D. Pipe movement
Answer: B
Explanation: CP polarizes (shifts) the structure to a more negative potential.
6. A high soil resistivity measurement indicates:
A. Higher corrosion risk
B. Lower corrosion current flow
C. No need for CP
D. Excess moisture
Answer: B
Explanation: High resistivity soils restrict current and can require more CP current.
7. A pipeline with a native potential of –400 mV Cu/CuSO₄ needs CP because:
A. It is too negative
B. It is too positive
C. It is at perfect protection
D. Horizontal drilling changed it
Answer: B
Explanation: –400 mV is not protective; CP shifts pipe to more negative potential.
8. An impressed current anode is typically made of:
A. Zinc
B. Aluminum alloy
C. Graphite, MMO, or high-silicon cast iron
D. Copper
Answer: C
Explanation: ICCP uses durable anodes with long service life.
9. A rectifier output of 25 amps and 12 volts indicates:
A. CP system is off
B. Low current density
C. Power consumption of 300 watts
D. Soil is very dry
,Answer: C
Explanation: P = IV → 25 × 12 = 300 W.
10. The purpose of a bond in CP is to:
A. Electrically isolate pipelines
B. Connect metallic structures to balance potentials
C. Increase resistance
D. Reduce voltage drop
Answer: B
Explanation: Bonds equalize potentials between interconnected systems.
11. The –850 mV protection criterion applies to:
A. Stainless steel
B. Buried ferrous pipelines
C. Aluminum tanks
D. Galvanized systems
Answer: B
Explanation: –850 mV vs Cu/CuSO₄ is the NACE criterion for steel in soil.
12. Coating holidays on pipelines cause:
A. No effect on CP
B. Reduced CP current
C. Increased current demand
D. Reduced rectifier output
Answer: C
Explanation: Bare steel increases current required to reach protection.
13. The best way to eliminate IR drop error in a reading is:
A. Use a digital voltmeter
B. Use instant-OFF techniques
C. Increase current output
D. Use AC measurement
Answer: B
Explanation: Instant-OFF isolates true pipe-to-soil polarization.
14. The primary function of a DC decoupler is to:
, A. Block AC and pass DC
B. Block DC and pass AC fault current
C. Increase CP current
D. Measure stray currents
Answer: B
Explanation: Decouplers allow AC to pass for safety but isolate DC for CP.
15. Current requirement tests determine:
A. Soil type
B. Minimum CP current needed to polarize structure
C. Pipeline diameter
D. Coating color
Answer: B
Explanation: Used to size CP systems.
16. A deep anode bed is used when:
A. Soil is shallow
B. High soil resistivity requires deeper placement
C. Pipeline is above ground
D. No current is needed
Answer: B
Explanation: Deep anode beds reduce resistance and increase current spread.
17. A sudden drop in rectifier voltage may indicate:
A. Stronger polarization
B. Anode grounding or short circuit
C. Good efficiency
D. Higher soil resistivity
Answer: B
Explanation: Shorts reduce circuit resistance → voltage drops.
18. The MOST common cause of pipeline AC corrosion risk is:
A. Soil moisture
B. Parallel high-voltage power lines
C. Marine clay
D. Weld joints
Answer: B
Explanation: Induced AC from HV transmission lines.
Certification Exam
1. The primary purpose of a cathodic protection survey is to:
A. Determine soil composition
B. Verify protective potentials on the structure
C. Measure pipe diameter
D. Inspect coating color
Answer: B
Explanation: CP surveys confirm that structure potentials are within protective criteria.
2. The most commonly used reference electrode for buried pipelines is:
A. Ag/AgCl
B. Cu/CuSO₄
C. Hg/HgSO₄
D. Zn/ZnSO₄
Answer: B
Explanation: Cu/CuSO₄ reference electrodes are standard for soil environments.
3. IR drop error in CP measurements is caused by:
A. Poor coatings only
B. Resistance in the electrolyte between structure and reference electrode
C. Voltage fluctuations in rectifiers
D. Soil temperature changes
Answer: B
Explanation: IR drop occurs due to current flowing through the soil resistance.
4. The most accurate potential measurement is obtained using:
A. Instant-OFF potential
B. ON potential
C. AC potential
D. Native potential
Answer: A
Explanation: Instant-OFF eliminates IR drop, giving accurate polarization levels.
,5. In CP systems, ‘polarization’ refers to:
A. Change in rectifier voltage
B. Shift in structure’s potential due to CP
C. Temperature rise in soil
D. Pipe movement
Answer: B
Explanation: CP polarizes (shifts) the structure to a more negative potential.
6. A high soil resistivity measurement indicates:
A. Higher corrosion risk
B. Lower corrosion current flow
C. No need for CP
D. Excess moisture
Answer: B
Explanation: High resistivity soils restrict current and can require more CP current.
7. A pipeline with a native potential of –400 mV Cu/CuSO₄ needs CP because:
A. It is too negative
B. It is too positive
C. It is at perfect protection
D. Horizontal drilling changed it
Answer: B
Explanation: –400 mV is not protective; CP shifts pipe to more negative potential.
8. An impressed current anode is typically made of:
A. Zinc
B. Aluminum alloy
C. Graphite, MMO, or high-silicon cast iron
D. Copper
Answer: C
Explanation: ICCP uses durable anodes with long service life.
9. A rectifier output of 25 amps and 12 volts indicates:
A. CP system is off
B. Low current density
C. Power consumption of 300 watts
D. Soil is very dry
,Answer: C
Explanation: P = IV → 25 × 12 = 300 W.
10. The purpose of a bond in CP is to:
A. Electrically isolate pipelines
B. Connect metallic structures to balance potentials
C. Increase resistance
D. Reduce voltage drop
Answer: B
Explanation: Bonds equalize potentials between interconnected systems.
11. The –850 mV protection criterion applies to:
A. Stainless steel
B. Buried ferrous pipelines
C. Aluminum tanks
D. Galvanized systems
Answer: B
Explanation: –850 mV vs Cu/CuSO₄ is the NACE criterion for steel in soil.
12. Coating holidays on pipelines cause:
A. No effect on CP
B. Reduced CP current
C. Increased current demand
D. Reduced rectifier output
Answer: C
Explanation: Bare steel increases current required to reach protection.
13. The best way to eliminate IR drop error in a reading is:
A. Use a digital voltmeter
B. Use instant-OFF techniques
C. Increase current output
D. Use AC measurement
Answer: B
Explanation: Instant-OFF isolates true pipe-to-soil polarization.
14. The primary function of a DC decoupler is to:
, A. Block AC and pass DC
B. Block DC and pass AC fault current
C. Increase CP current
D. Measure stray currents
Answer: B
Explanation: Decouplers allow AC to pass for safety but isolate DC for CP.
15. Current requirement tests determine:
A. Soil type
B. Minimum CP current needed to polarize structure
C. Pipeline diameter
D. Coating color
Answer: B
Explanation: Used to size CP systems.
16. A deep anode bed is used when:
A. Soil is shallow
B. High soil resistivity requires deeper placement
C. Pipeline is above ground
D. No current is needed
Answer: B
Explanation: Deep anode beds reduce resistance and increase current spread.
17. A sudden drop in rectifier voltage may indicate:
A. Stronger polarization
B. Anode grounding or short circuit
C. Good efficiency
D. Higher soil resistivity
Answer: B
Explanation: Shorts reduce circuit resistance → voltage drops.
18. The MOST common cause of pipeline AC corrosion risk is:
A. Soil moisture
B. Parallel high-voltage power lines
C. Marine clay
D. Weld joints
Answer: B
Explanation: Induced AC from HV transmission lines.
