NACE CP2 CATHODIC PROTECTION
TECHNICIAN LEVEL 2 EXAM 2026/2027
— 500 PRACTICE QUESTIONS &
ANSWERS WITH DETAILED
RATIONALES: AMPP CERTIFICATION
PREP | instant download | newest!
1. A buried carbon steel pipeline in a coastal marsh shows pitting corrosion
concentrated at the six o'clock position. The soil pH is 7.2 and dissolved oxygen
levels are lowest at the pipe bottom. Which electrochemical mechanism best
explains this localized attack?
A. Differential aeration cell formation due to oxygen concentration gradients
B. Galvanic coupling with copper grounding rods nearby
C. Microbiologically influenced corrosion from sulfate-reducing bacteria
D. Stray current discharge from an adjacent impressed current system
Correct answer: C. Rationale: Sulfate-reducing bacteria thrive in oxygen-depleted,
moist environments and produce hydrogen sulfide, causing localized pitting at the pipe
bottom.
2. During a pipeline inspection, a technician measures a structure-to-electrolyte
potential of -0.420 V CSE on bare steel in aerated soil. When the cathodic
protection system is energized, the potential shifts to -0.920 V CSE. Which
polarization component contributes most significantly to this 500 mV shift?
A. Concentration polarization from hydroxide ion accumulation
B. Activation polarization at the cathodic surface
C. Ohmic drop through the soil electrolyte path
D. Resistance polarization from surface film formation
Correct answer: B. Rationale: Activation polarization dominates at the cathode during
cathodic protection because the hydrogen evolution reaction requires an overpotential
to drive the reaction.
3. A zinc anode coupled to steel in seawater produces a measured current of 2.3
A. Over six months, the current decays to 1.1 A while the steel potential
remains protective. Which factor is the primary cause of this current reduction?
,A. Increased calcareous deposit formation on the steel cathode
B. Passivation of the zinc anode surface
C. Increased seawater temperature raising conductivity
D. Cathodic disbondment of the pipeline coating
Correct answer: A. Rationale: Calcareous deposits (calcium and magnesium
compounds) form on the cathodically protected steel surface, increasing polarization
resistance.
4. A CP technician observes that a rectifier has been providing stable DC output
for months, but in the past week the DC output current has risen by 30% with
no voltage change. Which cause is MOST likely?
A. Anode bed degradation
B. Improved coating
C. New coating holiday or increased CP demand on the structure
D. Rectifier diode failure
Correct answer: C. Rationale: With DC voltage constant and current rising, circuit
resistance has decreased. The most common cause is a new coating defect or damage
exposing more bare steel to electrolyte.
5. Which technique does a CP Technician use to locate small coating defects
along a pipeline without excavation?
A. Close Interval Potential Survey (CIPS)
B. Direct Current Voltage Gradient (DCVG) survey
C. Over-the-line structure potential at 1 km intervals
D. Pipe-to-electrolyte oscilloscope trace
Correct answer: B. Rationale: DCVG surveys are the primary above-ground technique
for locating and sizing pipeline coating defects.
6. During an instant-off survey on a pipeline with two rectifiers, both
interrupters are synchronized and run for one full cycle. The 'on' potential at
test station TS-15 is -1.080 V CSE and 'off' is -0.840 V CSE. What should the
technician report?
A. The 100 mV -850 mV polarized criterion; additional CP current or investigation is
required
B. The structure is overprotected
C. The interrupter is faulty
Correct answer: A. Rationale: The instant-off (polarized) potential of -0.840 V is less
negative than -0.850 V, so the criterion is NOT met. The IR drop (240 mV) is relatively
large.
7. Which of the following is MOST likely to cause static DC stray current
interference on a buried pipeline?
A. Adjacent DC transit system
B. Another pipeline's operating CP rectifier nearby
,C. Adjacent HVAC transmission line
D. Natural telluric currents
Correct answer: B. Rationale: Static (time-invariant) DC stray current most often comes
from a nearby operating CP rectifier on another pipeline.
8. A pipeline crossing a high-voltage AC transmission corridor shows 45 V AC
induced voltage at a test station. Per NACE SP0177 personnel safety guidance,
what action should the CP Technician take?
A. Continue normal work with insulated gloves
B. Stop work, mitigate induced AC to below the 15 V AC personnel safety threshold,
and notify supervision
C. Ignore it because CP is unaffected
D. Disconnect the bond
Correct answer: B. Rationale: NACE SP0177 identifies 15 V AC as a conservative
threshold for personnel safety.
9. A CP Technician measures a rectifier output of 14.0 V DC and 8.0 A DC. What
is the approximate DC output power?
A. 22 W
B. 1.75 W
C. 112 W
D. 80 W
Correct answer: C. Rationale: P = V × I = 14.0 V × 8.0 A = 112 W DC output power.
10. Which reference electrode conversion is correct?
A. Reading vs Ag/AgCl (sat KCl) ≈ Reading vs CSE + 119 mV (i.e., CSE reading is more
negative)
B. Reading vs CSE ≈ Reading vs SHE + 318 mV
C. Reading vs Zn reference ≈ 0
D. Reading vs Ag/AgCl is always 250 mV more negative than CSE
Correct answer: A. Rationale: CSE (+0.318 V vs SHE) is ~119 mV more positive than
saturated Ag/AgCl (+0.199 V vs SHE).
11. Why does a CP Technician use a 4-wire linear line-current test station
instead of a 2-wire shunt at remote pipeline locations?
A. Lower cost
B. The 4-wire (Kelvin) configuration eliminates lead resistance error when reading very
small mV drops along a known pipe span, giving accurate line-current measurement
C. 4 wires supply more current
D. Redundancy only
Correct answer: B. Rationale: The 4-wire configuration eliminates lead resistance error
when reading very small mV drops.
, 12. Which impressed-current anode type is DIMENSIONALLY STABLE (consumes
very little material during service)?
A. High-silicon cast iron (HSCI)
B. Graphite
C. Mixed-metal oxide (MMO) on titanium
D. Aluminum-zinc-indium
Correct answer: C. Rationale: MMO coated titanium anodes have extremely low
consumption rates (typically <1 mg/A·yr) and are considered dimensionally stable.
13. What is the PRIMARY reason to install a polarization cell replacement (PCR)
or solid-state decoupler on a bonded-to-ground CP system?
A. Pass lightning and AC fault current to ground while blocking steady-state DC CP
current
B. Increase anode current
C. Replace a rectifier
D. Measure pipe temperature
Correct answer: A. Rationale: Solid-state decouplers provide high DC impedance
(blocking CP current from draining to ground) while presenting low AC impedance.
14. In cathodic protection, the fundamental objective is to reduce the corrosion
rate of a metallic structure by shifting its electrochemical behavior in the
cathodic direction. Which statement best describes the mechanism by which
cathodic protection reduces corrosion of a steel pipeline?
A. It eliminates all electrochemical reactions on the pipeline surface by making the
steel electrically neutral
B. It causes the protected structure to function preferentially as a cathode, reducing the
tendency for metal oxidation at anodic sites
C. It increases the rate of oxygen reduction at the cathode
D. It increases the rate of metal dissolution at the anode
Correct answer: B. Rationale: Cathodic protection works by making the protected
structure the cathode of an electrochemical cell, reducing oxidation.
15. A buried carbon-steel pipeline is protected by an impressed-current
cathodic protection system. During a routine survey, the technician observes
that the rectifier output current has gradually decreased while the rectifier
voltage has increased. The structure-to-electrolyte potentials are also becoming
less negative. Which interpretation is most technically appropriate?
A. The system is necessarily overprotecting the pipeline because the rectifier voltage
has increased
B. The increasing voltage and decreasing current may indicate increasing circuit
resistance, requiring investigation of anodes, cables, connections, soil conditions, or
other circuit components
C. The pipeline coating must have become substantially better because less current is
being delivered
TECHNICIAN LEVEL 2 EXAM 2026/2027
— 500 PRACTICE QUESTIONS &
ANSWERS WITH DETAILED
RATIONALES: AMPP CERTIFICATION
PREP | instant download | newest!
1. A buried carbon steel pipeline in a coastal marsh shows pitting corrosion
concentrated at the six o'clock position. The soil pH is 7.2 and dissolved oxygen
levels are lowest at the pipe bottom. Which electrochemical mechanism best
explains this localized attack?
A. Differential aeration cell formation due to oxygen concentration gradients
B. Galvanic coupling with copper grounding rods nearby
C. Microbiologically influenced corrosion from sulfate-reducing bacteria
D. Stray current discharge from an adjacent impressed current system
Correct answer: C. Rationale: Sulfate-reducing bacteria thrive in oxygen-depleted,
moist environments and produce hydrogen sulfide, causing localized pitting at the pipe
bottom.
2. During a pipeline inspection, a technician measures a structure-to-electrolyte
potential of -0.420 V CSE on bare steel in aerated soil. When the cathodic
protection system is energized, the potential shifts to -0.920 V CSE. Which
polarization component contributes most significantly to this 500 mV shift?
A. Concentration polarization from hydroxide ion accumulation
B. Activation polarization at the cathodic surface
C. Ohmic drop through the soil electrolyte path
D. Resistance polarization from surface film formation
Correct answer: B. Rationale: Activation polarization dominates at the cathode during
cathodic protection because the hydrogen evolution reaction requires an overpotential
to drive the reaction.
3. A zinc anode coupled to steel in seawater produces a measured current of 2.3
A. Over six months, the current decays to 1.1 A while the steel potential
remains protective. Which factor is the primary cause of this current reduction?
,A. Increased calcareous deposit formation on the steel cathode
B. Passivation of the zinc anode surface
C. Increased seawater temperature raising conductivity
D. Cathodic disbondment of the pipeline coating
Correct answer: A. Rationale: Calcareous deposits (calcium and magnesium
compounds) form on the cathodically protected steel surface, increasing polarization
resistance.
4. A CP technician observes that a rectifier has been providing stable DC output
for months, but in the past week the DC output current has risen by 30% with
no voltage change. Which cause is MOST likely?
A. Anode bed degradation
B. Improved coating
C. New coating holiday or increased CP demand on the structure
D. Rectifier diode failure
Correct answer: C. Rationale: With DC voltage constant and current rising, circuit
resistance has decreased. The most common cause is a new coating defect or damage
exposing more bare steel to electrolyte.
5. Which technique does a CP Technician use to locate small coating defects
along a pipeline without excavation?
A. Close Interval Potential Survey (CIPS)
B. Direct Current Voltage Gradient (DCVG) survey
C. Over-the-line structure potential at 1 km intervals
D. Pipe-to-electrolyte oscilloscope trace
Correct answer: B. Rationale: DCVG surveys are the primary above-ground technique
for locating and sizing pipeline coating defects.
6. During an instant-off survey on a pipeline with two rectifiers, both
interrupters are synchronized and run for one full cycle. The 'on' potential at
test station TS-15 is -1.080 V CSE and 'off' is -0.840 V CSE. What should the
technician report?
A. The 100 mV -850 mV polarized criterion; additional CP current or investigation is
required
B. The structure is overprotected
C. The interrupter is faulty
Correct answer: A. Rationale: The instant-off (polarized) potential of -0.840 V is less
negative than -0.850 V, so the criterion is NOT met. The IR drop (240 mV) is relatively
large.
7. Which of the following is MOST likely to cause static DC stray current
interference on a buried pipeline?
A. Adjacent DC transit system
B. Another pipeline's operating CP rectifier nearby
,C. Adjacent HVAC transmission line
D. Natural telluric currents
Correct answer: B. Rationale: Static (time-invariant) DC stray current most often comes
from a nearby operating CP rectifier on another pipeline.
8. A pipeline crossing a high-voltage AC transmission corridor shows 45 V AC
induced voltage at a test station. Per NACE SP0177 personnel safety guidance,
what action should the CP Technician take?
A. Continue normal work with insulated gloves
B. Stop work, mitigate induced AC to below the 15 V AC personnel safety threshold,
and notify supervision
C. Ignore it because CP is unaffected
D. Disconnect the bond
Correct answer: B. Rationale: NACE SP0177 identifies 15 V AC as a conservative
threshold for personnel safety.
9. A CP Technician measures a rectifier output of 14.0 V DC and 8.0 A DC. What
is the approximate DC output power?
A. 22 W
B. 1.75 W
C. 112 W
D. 80 W
Correct answer: C. Rationale: P = V × I = 14.0 V × 8.0 A = 112 W DC output power.
10. Which reference electrode conversion is correct?
A. Reading vs Ag/AgCl (sat KCl) ≈ Reading vs CSE + 119 mV (i.e., CSE reading is more
negative)
B. Reading vs CSE ≈ Reading vs SHE + 318 mV
C. Reading vs Zn reference ≈ 0
D. Reading vs Ag/AgCl is always 250 mV more negative than CSE
Correct answer: A. Rationale: CSE (+0.318 V vs SHE) is ~119 mV more positive than
saturated Ag/AgCl (+0.199 V vs SHE).
11. Why does a CP Technician use a 4-wire linear line-current test station
instead of a 2-wire shunt at remote pipeline locations?
A. Lower cost
B. The 4-wire (Kelvin) configuration eliminates lead resistance error when reading very
small mV drops along a known pipe span, giving accurate line-current measurement
C. 4 wires supply more current
D. Redundancy only
Correct answer: B. Rationale: The 4-wire configuration eliminates lead resistance error
when reading very small mV drops.
, 12. Which impressed-current anode type is DIMENSIONALLY STABLE (consumes
very little material during service)?
A. High-silicon cast iron (HSCI)
B. Graphite
C. Mixed-metal oxide (MMO) on titanium
D. Aluminum-zinc-indium
Correct answer: C. Rationale: MMO coated titanium anodes have extremely low
consumption rates (typically <1 mg/A·yr) and are considered dimensionally stable.
13. What is the PRIMARY reason to install a polarization cell replacement (PCR)
or solid-state decoupler on a bonded-to-ground CP system?
A. Pass lightning and AC fault current to ground while blocking steady-state DC CP
current
B. Increase anode current
C. Replace a rectifier
D. Measure pipe temperature
Correct answer: A. Rationale: Solid-state decouplers provide high DC impedance
(blocking CP current from draining to ground) while presenting low AC impedance.
14. In cathodic protection, the fundamental objective is to reduce the corrosion
rate of a metallic structure by shifting its electrochemical behavior in the
cathodic direction. Which statement best describes the mechanism by which
cathodic protection reduces corrosion of a steel pipeline?
A. It eliminates all electrochemical reactions on the pipeline surface by making the
steel electrically neutral
B. It causes the protected structure to function preferentially as a cathode, reducing the
tendency for metal oxidation at anodic sites
C. It increases the rate of oxygen reduction at the cathode
D. It increases the rate of metal dissolution at the anode
Correct answer: B. Rationale: Cathodic protection works by making the protected
structure the cathode of an electrochemical cell, reducing oxidation.
15. A buried carbon-steel pipeline is protected by an impressed-current
cathodic protection system. During a routine survey, the technician observes
that the rectifier output current has gradually decreased while the rectifier
voltage has increased. The structure-to-electrolyte potentials are also becoming
less negative. Which interpretation is most technically appropriate?
A. The system is necessarily overprotecting the pipeline because the rectifier voltage
has increased
B. The increasing voltage and decreasing current may indicate increasing circuit
resistance, requiring investigation of anodes, cables, connections, soil conditions, or
other circuit components
C. The pipeline coating must have become substantially better because less current is
being delivered
