PHMSA Corrosion Control of Pipeline Systems Exam Practice
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1. Which of the following is the primary cause of external corrosion on pipelines?
A) High operating pressure
B) Soil moisture and chemistry
C) Pipeline vibration
D) Cathodic protection systems
Answer: B
Rationale: External corrosion is primarily influenced by soil environment factors such as moisture, pH, resistivity,
and presence of electrolytes .
2. What is the main purpose of cathodic protection (CP) on pipelines?
A) Increase pipeline pressure
B) Prevent external corrosion
C) Control internal flow velocity
D) Detect leaks
Answer: B
Rationale: CP works by making the pipeline the cathode of an electrochemical cell, preventing metal loss from
corrosion .
3. What type of current is commonly used in impressed current cathodic protection (ICCP) systems?
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,A) Alternating current (AC)
B) Direct current (DC)
C) Pulsed current
D) None
Answer: B
Rationale: ICCP systems use DC to drive electrons to the pipeline to suppress corrosion .
4. Which coating type provides the primary defense against external pipeline corrosion?
A) Asphalt coating
B) Fusion-bonded epoxy (FBE)
C) Galvanic coating
D) Paint only
Answer: B
Rationale: Coatings like FBE provide a barrier against moisture and corrosive elements, reducing external
corrosion risk .
5. A pipeline operating in soil with low resistivity is at risk of:
A) Internal corrosion
B) External corrosion
C) Mechanical failure
D) Flow turbulence
Answer: B
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,Rationale: Low soil resistivity increases the rate of electrochemical reactions, accelerating external corrosion .
6. The purpose of a reference electrode in CP testing is to:
A) Measure pipeline diameter
B) Measure pipe-to-soil potential
C) Apply protective coatings
D) Detect cracks
Answer: B
Rationale: Reference electrodes provide a stable standard for measuring pipe-to-soil potential to evaluate CP
effectiveness .
7. Under 49 CFR 192.451, what is the minimum cathodic protection level for steel pipelines in contact with
electrolyte?
A) -0.85 V vs. Cu/CuSO₄
B) -1.20 V vs. Cu/CuSO₄
C) -0.50 V vs. Ag/AgCl
D) 0.00 V vs. saturated calomel electrode
Answer: A
Rationale: The -0.85 V CSE criterion is the standard for steel in soil or water .
8. According to 49 CFR 195.551, external corrosion control must include:
A) Coating only
B) Cathodic protection only
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, C) Coating AND cathodic protection
D) Corrosion inhibitors only
Answer: C
Rationale: Both coating and CP are required for buried/submerged metallic hazardous liquid pipelines .
9. How often must cathodic protection rectifiers be visually inspected under 49 CFR 192.463?
A) Weekly
B) Monthly
C) Every 60 days
D) Annually
Answer: C
Rationale: Rectifier inspections are required every 60 days but can be extended to 90 days if remote monitoring
is used .
10. Under 49 CFR 192.465(c), what is the maximum interval between cathodic protection tests?
A) 6 months
B) 1 year
C) 2 years
D) 5 years
Answer: B
Rationale: Annual testing is mandatory for all cathodically protected pipelines .
4|Page SUCCESS!!!
With Questions and Correct Answers (100% Verified
Answers) Plus Rationales 2026 Q&A | 100% Guaranteed
Pass!!!
1. Which of the following is the primary cause of external corrosion on pipelines?
A) High operating pressure
B) Soil moisture and chemistry
C) Pipeline vibration
D) Cathodic protection systems
Answer: B
Rationale: External corrosion is primarily influenced by soil environment factors such as moisture, pH, resistivity,
and presence of electrolytes .
2. What is the main purpose of cathodic protection (CP) on pipelines?
A) Increase pipeline pressure
B) Prevent external corrosion
C) Control internal flow velocity
D) Detect leaks
Answer: B
Rationale: CP works by making the pipeline the cathode of an electrochemical cell, preventing metal loss from
corrosion .
3. What type of current is commonly used in impressed current cathodic protection (ICCP) systems?
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,A) Alternating current (AC)
B) Direct current (DC)
C) Pulsed current
D) None
Answer: B
Rationale: ICCP systems use DC to drive electrons to the pipeline to suppress corrosion .
4. Which coating type provides the primary defense against external pipeline corrosion?
A) Asphalt coating
B) Fusion-bonded epoxy (FBE)
C) Galvanic coating
D) Paint only
Answer: B
Rationale: Coatings like FBE provide a barrier against moisture and corrosive elements, reducing external
corrosion risk .
5. A pipeline operating in soil with low resistivity is at risk of:
A) Internal corrosion
B) External corrosion
C) Mechanical failure
D) Flow turbulence
Answer: B
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,Rationale: Low soil resistivity increases the rate of electrochemical reactions, accelerating external corrosion .
6. The purpose of a reference electrode in CP testing is to:
A) Measure pipeline diameter
B) Measure pipe-to-soil potential
C) Apply protective coatings
D) Detect cracks
Answer: B
Rationale: Reference electrodes provide a stable standard for measuring pipe-to-soil potential to evaluate CP
effectiveness .
7. Under 49 CFR 192.451, what is the minimum cathodic protection level for steel pipelines in contact with
electrolyte?
A) -0.85 V vs. Cu/CuSO₄
B) -1.20 V vs. Cu/CuSO₄
C) -0.50 V vs. Ag/AgCl
D) 0.00 V vs. saturated calomel electrode
Answer: A
Rationale: The -0.85 V CSE criterion is the standard for steel in soil or water .
8. According to 49 CFR 195.551, external corrosion control must include:
A) Coating only
B) Cathodic protection only
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, C) Coating AND cathodic protection
D) Corrosion inhibitors only
Answer: C
Rationale: Both coating and CP are required for buried/submerged metallic hazardous liquid pipelines .
9. How often must cathodic protection rectifiers be visually inspected under 49 CFR 192.463?
A) Weekly
B) Monthly
C) Every 60 days
D) Annually
Answer: C
Rationale: Rectifier inspections are required every 60 days but can be extended to 90 days if remote monitoring
is used .
10. Under 49 CFR 192.465(c), what is the maximum interval between cathodic protection tests?
A) 6 months
B) 1 year
C) 2 years
D) 5 years
Answer: B
Rationale: Annual testing is mandatory for all cathodically protected pipelines .
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