API 570 Piping Inspector Examination
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
Question 1
A piping system constructed of SA-106 Grade B carbon steel operates at 400°F and
600 psig. The inspector notes wall thinning due to general corrosion. The original
nominal wall thickness is 0.500 in., and the minimum required wall thickness per
the design code is 0.375 in. The measured minimum wall thickness is 0.340 in.
What is the inspector’s correct course of action?
A. Approve continued operation because the measured thickness is above the
retirement thickness.
B. Require an immediate pressure reduction to 50% of design pressure.
C. Issue a non-conformance report and recommend repair or replacement before
further operation.
D. Recalculate the MAWP using the measured thickness and compare to operating
pressure.
Answer: C – The measured thickness (0.340 in.) is below the minimum required
thickness (0.375 in.), so the component is unfit for service. The inspector must not
approve continued operation; repair or replacement is required. Simply
recalculating MAWP does not override the code minimum, and pressure reduction
is not a permanent fix without engineering evaluation.
Question 2
According to API 570, which of the following is the primary responsibility of the
,piping inspector regarding corrosion under insulation (CUI)?
A. To ensure that all insulation is removed annually for visual inspection.
B. To develop a CUI inspection strategy based on service temperature, insulation
type, and environmental conditions.
C. To replace all insulation with non-absorbent materials regardless of cost.
D. To rely solely on radiography for CUI detection.
Answer: B – API 570 requires inspectors to implement a risk-based inspection plan
for CUI, considering factors like temperature cycles, moisture ingress, and coating
condition. Annual removal of all insulation is not practical or required; radiography
is a supplemental tool, not the sole method.
Question 3
A piping circuit has been in sour service (wet H₂S) for 10 years. The inspector
observes small blisters on the external surface near a girth weld. What is the most
likely damage mechanism?
A. Stress corrosion cracking (SCC).
B. Hydrogen-induced cracking (HIC) and blistering.
C. Graphitization.
D. Creep damage.
Answer: B – Wet H₂S service is known to cause hydrogen-induced cracking and
blistering, particularly in susceptible carbon steels. SCC is chloride-related,
graphitization occurs at high temperatures, and creep is time-dependent at
elevated temperatures.
Question 4
When performing a visual inspection of a flanged joint, the inspector finds that
the gasket has extruded slightly beyond the flange face. This is a sign of:
A. Proper gasket compression.
B. Over-tightening of bolts.
,C. Under-tightening of bolts.
D. Incorrect gasket material selection.
Answer: B – Gasket extrusion beyond the flange face typically indicates excessive
bolt torque, which can crush the gasket and lead to loss of seal integrity. Proper
compression should contain the gasket within the flange faces.
Question 5
What is the minimum frequency for thickness monitoring of a piping system
classified as "moderately severe" corrosion service under API 570?
A. Every 5 years.
B. Every 3 years.
C. Every 2 years.
D. Annually.
Answer: D – API 570 Table 4-1 specifies that for moderately severe corrosion
service, the maximum interval between thickness inspections is 1 year (annual).
Severe service may require shorter intervals, while mild service allows up to 5
years.
Question 6
The design temperature of a piping system is 750°F, and the material is SA-335
P11 (1¼ Cr-½ Mo). Which damage mechanism should be of primary concern
during inspection?
A. Sulfidation.
B. Creep.
C. Temper embrittlement.
D. Hydrogen attack.
Answer: B – SA-335 P11 is a creep-strength-enhanced ferritic alloy; at 750°F, it is
approaching its creep range (typically above 700°F for this material). Creep
damage (voids, cracking) is the primary concern. Sulfidation requires higher sulfur
, environments, temper embrittlement occurs in the 700-1000°F range but is less
acute than creep, and hydrogen attack requires high partial pressures of hydrogen.
Question 7
According to ASME B31.3, which of the following is an acceptable NDE method for
detecting surface discontinuities in carbon steel piping?
A. Ultrasonic thickness gauging.
B. Magnetic particle examination.
C. Radiographic testing.
D. Eddy current testing.
Answer: B – Magnetic particle examination (MT) is specifically used for surface
and near-surface flaw detection in ferromagnetic materials like carbon steel. UT
thickness gauging measures wall loss, RT detects volumetric internal flaws, and
eddy current is more common for tubing or conductivity changes.
Question 8
During a hydrostatic test of a newly installed piping system, the test pressure is 1.5
times the design pressure. The system holds pressure for 2 hours with no visible
leaks. The inspector should:
A. Accept the system and sign off.
B. Require a pneumatic test because hydrostatic testing may mask small leaks.
C. Check for pressure drop due to temperature stabilization and re-evaluate.
D. Extend the test duration to 4 hours to ensure integrity.
Answer: C – ASME B31.3 requires that hydrostatic test pressure be maintained,
but temperature changes can cause pressure fluctuations. The inspector must
ensure that pressure is stable after temperature equalization. A 2-hour hold is
generally sufficient if no leaks and pressure is stable; extending without cause is
not required, and pneumatic testing is more hazardous, not a substitute.
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
Question 1
A piping system constructed of SA-106 Grade B carbon steel operates at 400°F and
600 psig. The inspector notes wall thinning due to general corrosion. The original
nominal wall thickness is 0.500 in., and the minimum required wall thickness per
the design code is 0.375 in. The measured minimum wall thickness is 0.340 in.
What is the inspector’s correct course of action?
A. Approve continued operation because the measured thickness is above the
retirement thickness.
B. Require an immediate pressure reduction to 50% of design pressure.
C. Issue a non-conformance report and recommend repair or replacement before
further operation.
D. Recalculate the MAWP using the measured thickness and compare to operating
pressure.
Answer: C – The measured thickness (0.340 in.) is below the minimum required
thickness (0.375 in.), so the component is unfit for service. The inspector must not
approve continued operation; repair or replacement is required. Simply
recalculating MAWP does not override the code minimum, and pressure reduction
is not a permanent fix without engineering evaluation.
Question 2
According to API 570, which of the following is the primary responsibility of the
,piping inspector regarding corrosion under insulation (CUI)?
A. To ensure that all insulation is removed annually for visual inspection.
B. To develop a CUI inspection strategy based on service temperature, insulation
type, and environmental conditions.
C. To replace all insulation with non-absorbent materials regardless of cost.
D. To rely solely on radiography for CUI detection.
Answer: B – API 570 requires inspectors to implement a risk-based inspection plan
for CUI, considering factors like temperature cycles, moisture ingress, and coating
condition. Annual removal of all insulation is not practical or required; radiography
is a supplemental tool, not the sole method.
Question 3
A piping circuit has been in sour service (wet H₂S) for 10 years. The inspector
observes small blisters on the external surface near a girth weld. What is the most
likely damage mechanism?
A. Stress corrosion cracking (SCC).
B. Hydrogen-induced cracking (HIC) and blistering.
C. Graphitization.
D. Creep damage.
Answer: B – Wet H₂S service is known to cause hydrogen-induced cracking and
blistering, particularly in susceptible carbon steels. SCC is chloride-related,
graphitization occurs at high temperatures, and creep is time-dependent at
elevated temperatures.
Question 4
When performing a visual inspection of a flanged joint, the inspector finds that
the gasket has extruded slightly beyond the flange face. This is a sign of:
A. Proper gasket compression.
B. Over-tightening of bolts.
,C. Under-tightening of bolts.
D. Incorrect gasket material selection.
Answer: B – Gasket extrusion beyond the flange face typically indicates excessive
bolt torque, which can crush the gasket and lead to loss of seal integrity. Proper
compression should contain the gasket within the flange faces.
Question 5
What is the minimum frequency for thickness monitoring of a piping system
classified as "moderately severe" corrosion service under API 570?
A. Every 5 years.
B. Every 3 years.
C. Every 2 years.
D. Annually.
Answer: D – API 570 Table 4-1 specifies that for moderately severe corrosion
service, the maximum interval between thickness inspections is 1 year (annual).
Severe service may require shorter intervals, while mild service allows up to 5
years.
Question 6
The design temperature of a piping system is 750°F, and the material is SA-335
P11 (1¼ Cr-½ Mo). Which damage mechanism should be of primary concern
during inspection?
A. Sulfidation.
B. Creep.
C. Temper embrittlement.
D. Hydrogen attack.
Answer: B – SA-335 P11 is a creep-strength-enhanced ferritic alloy; at 750°F, it is
approaching its creep range (typically above 700°F for this material). Creep
damage (voids, cracking) is the primary concern. Sulfidation requires higher sulfur
, environments, temper embrittlement occurs in the 700-1000°F range but is less
acute than creep, and hydrogen attack requires high partial pressures of hydrogen.
Question 7
According to ASME B31.3, which of the following is an acceptable NDE method for
detecting surface discontinuities in carbon steel piping?
A. Ultrasonic thickness gauging.
B. Magnetic particle examination.
C. Radiographic testing.
D. Eddy current testing.
Answer: B – Magnetic particle examination (MT) is specifically used for surface
and near-surface flaw detection in ferromagnetic materials like carbon steel. UT
thickness gauging measures wall loss, RT detects volumetric internal flaws, and
eddy current is more common for tubing or conductivity changes.
Question 8
During a hydrostatic test of a newly installed piping system, the test pressure is 1.5
times the design pressure. The system holds pressure for 2 hours with no visible
leaks. The inspector should:
A. Accept the system and sign off.
B. Require a pneumatic test because hydrostatic testing may mask small leaks.
C. Check for pressure drop due to temperature stabilization and re-evaluate.
D. Extend the test duration to 4 hours to ensure integrity.
Answer: C – ASME B31.3 requires that hydrostatic test pressure be maintained,
but temperature changes can cause pressure fluctuations. The inspector must
ensure that pressure is stable after temperature equalization. A 2-hour hold is
generally sufficient if no leaks and pressure is stable; extending without cause is
not required, and pneumatic testing is more hazardous, not a substitute.
