MARK'S API 510 EVALUATION EXAM 2026/2027
QUESTIONS AND SOLUTIONS RATED A+
✔✔Thickness measurements are taken to verify the :
a) Thickness of the vessel component
b) Exchange rate between Canadian $ and USA $
c) Relative humidity
d) Number of fatigue cycles - ✔✔A
✔✔The Inspector should consult with a Corrosion Specialist when:
a) CUI is discovered during the External Inspection
b) The grounding connection is found corroded
c) The short-term corrosion rate changes significantly
d) Determining an External Inspection interval - ✔✔C
✔✔Who must assure that personnel performing thickness readings are trained and
qualified?
a) Authorized Inspector
b) The Authorized Inspection Agency
c) Someone with a Level III UT certification
d) Owner / User - ✔✔D
✔✔CUI is an inspection concern for insulated carbon steel vessels that operate
between:
a) 0 to 100°F
b) 10 to 350°F
c) 25 to 250° F
d) 40 to 125°F
e) 140 to 350°F - ✔✔B
✔✔CUI is an inspection concern for insulated austenitic stainless steel vessels that
operate between:
a) 0 to 100°F
b) 10 to 350°F
c) 25 to 250° F
d) 40 to 125°F
e) 140 to 350°F - ✔✔E
✔✔CUI is an inspection concern for insulated duplex stainless steel vessels that
operate between:
a) 10 to 350°F
b) 40 to 125°F
c) 140 to 350°F
d) 280 to 350°F - ✔✔D
,✔✔CUI is an inspection concern for insulated vessels that operate at 500°F and:
a) Are in intermittent service
b) Are made of stainless steel
c) Are made of low chromes
d) Have poorly maintained insulation - ✔✔A
✔✔Which of the following insulated vessels is most likely to experience CUI?
a) CS vessel that operates at 600°F but is in an intermittent service
b) CS vessel that operates continuously at 375°F
c) CS vessel that operates continuously at -20°F
d) CS vessel that operates at cyclic temperatures ranging from 400-600°F
e) Austenitic SS vessel that operates continuously at 100°F - ✔✔A
✔✔CUI damage on carbon steel and low alloy materials usually appears as:
a) Cracks
b) Isolated deep pitting
c) Localized corrosion
d) Uniform corrosion - ✔✔C
✔✔CUI of austenitic and duplex stainless steel vessels:
a) Occurs at temperatures between -10 to 125°F
b) Normally appears as stress corrosion cracking
c) Is the result of using insulation that contains a sulfur compound
d) Normally causes deep isolated pitting - ✔✔B
✔✔CUI damage:
a) Is usually not a major concern
b) Is usually a concern on insulated vessels once the vessel is 5 years old
c) Is very predictable
d) Can be very unpredictable - ✔✔D
✔✔Which of the following is NOT a most susceptible area for CUI damage on an
insulated vessel?
a) Below stiffening rings
b) Bottom heads
c) Ladder clips
d) Nozzles - ✔✔A
✔✔External Inspection is planned for an insulated vessel. How much insulation should
be removed to check the conditions of the external surface?
a) A minimum of 10% of the insulation should be removed
b) Remove a small area of insulation on each shell course, and each head
c) Remove at least one small area of insulation in the most suspect area
,d) Insulation removal is not required unless there is a reason to suspect that corrosion is
occurring under the insulation? - ✔✔D
✔✔Which type of insulation is MOST likely to absorb and hold water?
a) Calcium Silicate
b) Cellular Glass
c) Fiberglass
d) Mineral Wool - ✔✔A
✔✔A CML is a spot for:
a) Checking for various damage types, (wall loss, cracking, or HTHA)
b) Only taking UT thickness readings
c) Only taking UT or Profile RT thickness readings
d) Use in RBI assessments and is called Corrosion Monitored Logic - ✔✔A
✔✔When thickness readings are due, what is the minimum number of thickness
readings that should be taken?
a) One on each head and shell course, and one on each nozzle
b) Two on each head and three on each shell course
c) Four on each head and each shell course, and one on 50% of the nozzles
d) A represented number of reading on heads, shell and nozzles - ✔✔D
✔✔Thickness readings are taken on a vessel. Which CMLs must always be included in
this exam?
a) All the CMLs assigned to this vessel
b) CMLs with the highest corrosion rate
c) CMLs with the highest corrosion rate and CML with lowest remaining life
d) CMLs with highest corrosion rate and highest remaining life
e) Whichever CMLs are selected by the Examiner
f) Whichever CMLs are selected by the Inspector - ✔✔C
✔✔A minimum number of CMLs on a vessel is acceptable when the:
a) Corrosion rate is low and localized corrosion is not expected
b) Design pressure is less than 100psig
c) Vessel is in an intermittent service
d) Process fluid is either a Class 2 or Class 3 - ✔✔A
✔✔UT thickness readings will be taken on a vessel. Which of the following best
describes the process for taking readings at a specific examination point?
a) Take one reading and record
b) Take multiple readings and record the highest reading of the set
c) Take multiple readings and record the average of the set
d) Take multiple readings and record the lowest reading of the set
e) Take multiple readings and record the lowest reading or average of the set
, f) Take multiple readings and record the highest reading or average of the set - ✔✔E
✔✔CMLs should always be:
a) Measured with a digital UT instrument
b) Measured by someone certified to ASNT
c) Permanently marked on a drawing and/or on the vessel
d) Placed on each nozzle - ✔✔C
✔✔Who should be consulted about placement and number of CMLs for vessels with
suspected localized corrosion?
a) Corrosion Specialist
b) Engineer
c) Examiner
d) Inspector - ✔✔A
✔✔Which of the following conditions would justify fewer CMLs on a vessel?
a) Corrosion Rate is less than 0.010 ipy
b) Localize corrosion is expected
c) Uniform corrosion is expected
d) Vessel contains propane - ✔✔C
✔✔The number of CMLs can be eliminated or reduced if:
a) The consequence of vessel failure is low
b) The probability of vessel failure is low
c) Both the consequence and the probability of vessel failure is low
d) Either the consequence or the probability of vessel failure is low - ✔✔D
✔✔Who should be consulted is CMLs on a vessel is eliminated?
a) Corrosion Specialist
b) Engineer
c) Both the Inspector and the Engineer
d) Both the Inspector and the Corrosion Specialist - ✔✔A
✔✔Who should be consulted if CMLs on a vessel are substantially reduced?
a) Corrosion Specialist
b) Engineer
c) Both the Inspector and the Engineer
d) Both the Inspector and the Corrosion Specialist - ✔✔A
✔✔The NDE method called Alternating Current Flux Leakage is useful in finding:
a) MIC damage
b) Porosity in weld
c) Subsurface cracks
d) Surface-breaking cracks - ✔✔D
QUESTIONS AND SOLUTIONS RATED A+
✔✔Thickness measurements are taken to verify the :
a) Thickness of the vessel component
b) Exchange rate between Canadian $ and USA $
c) Relative humidity
d) Number of fatigue cycles - ✔✔A
✔✔The Inspector should consult with a Corrosion Specialist when:
a) CUI is discovered during the External Inspection
b) The grounding connection is found corroded
c) The short-term corrosion rate changes significantly
d) Determining an External Inspection interval - ✔✔C
✔✔Who must assure that personnel performing thickness readings are trained and
qualified?
a) Authorized Inspector
b) The Authorized Inspection Agency
c) Someone with a Level III UT certification
d) Owner / User - ✔✔D
✔✔CUI is an inspection concern for insulated carbon steel vessels that operate
between:
a) 0 to 100°F
b) 10 to 350°F
c) 25 to 250° F
d) 40 to 125°F
e) 140 to 350°F - ✔✔B
✔✔CUI is an inspection concern for insulated austenitic stainless steel vessels that
operate between:
a) 0 to 100°F
b) 10 to 350°F
c) 25 to 250° F
d) 40 to 125°F
e) 140 to 350°F - ✔✔E
✔✔CUI is an inspection concern for insulated duplex stainless steel vessels that
operate between:
a) 10 to 350°F
b) 40 to 125°F
c) 140 to 350°F
d) 280 to 350°F - ✔✔D
,✔✔CUI is an inspection concern for insulated vessels that operate at 500°F and:
a) Are in intermittent service
b) Are made of stainless steel
c) Are made of low chromes
d) Have poorly maintained insulation - ✔✔A
✔✔Which of the following insulated vessels is most likely to experience CUI?
a) CS vessel that operates at 600°F but is in an intermittent service
b) CS vessel that operates continuously at 375°F
c) CS vessel that operates continuously at -20°F
d) CS vessel that operates at cyclic temperatures ranging from 400-600°F
e) Austenitic SS vessel that operates continuously at 100°F - ✔✔A
✔✔CUI damage on carbon steel and low alloy materials usually appears as:
a) Cracks
b) Isolated deep pitting
c) Localized corrosion
d) Uniform corrosion - ✔✔C
✔✔CUI of austenitic and duplex stainless steel vessels:
a) Occurs at temperatures between -10 to 125°F
b) Normally appears as stress corrosion cracking
c) Is the result of using insulation that contains a sulfur compound
d) Normally causes deep isolated pitting - ✔✔B
✔✔CUI damage:
a) Is usually not a major concern
b) Is usually a concern on insulated vessels once the vessel is 5 years old
c) Is very predictable
d) Can be very unpredictable - ✔✔D
✔✔Which of the following is NOT a most susceptible area for CUI damage on an
insulated vessel?
a) Below stiffening rings
b) Bottom heads
c) Ladder clips
d) Nozzles - ✔✔A
✔✔External Inspection is planned for an insulated vessel. How much insulation should
be removed to check the conditions of the external surface?
a) A minimum of 10% of the insulation should be removed
b) Remove a small area of insulation on each shell course, and each head
c) Remove at least one small area of insulation in the most suspect area
,d) Insulation removal is not required unless there is a reason to suspect that corrosion is
occurring under the insulation? - ✔✔D
✔✔Which type of insulation is MOST likely to absorb and hold water?
a) Calcium Silicate
b) Cellular Glass
c) Fiberglass
d) Mineral Wool - ✔✔A
✔✔A CML is a spot for:
a) Checking for various damage types, (wall loss, cracking, or HTHA)
b) Only taking UT thickness readings
c) Only taking UT or Profile RT thickness readings
d) Use in RBI assessments and is called Corrosion Monitored Logic - ✔✔A
✔✔When thickness readings are due, what is the minimum number of thickness
readings that should be taken?
a) One on each head and shell course, and one on each nozzle
b) Two on each head and three on each shell course
c) Four on each head and each shell course, and one on 50% of the nozzles
d) A represented number of reading on heads, shell and nozzles - ✔✔D
✔✔Thickness readings are taken on a vessel. Which CMLs must always be included in
this exam?
a) All the CMLs assigned to this vessel
b) CMLs with the highest corrosion rate
c) CMLs with the highest corrosion rate and CML with lowest remaining life
d) CMLs with highest corrosion rate and highest remaining life
e) Whichever CMLs are selected by the Examiner
f) Whichever CMLs are selected by the Inspector - ✔✔C
✔✔A minimum number of CMLs on a vessel is acceptable when the:
a) Corrosion rate is low and localized corrosion is not expected
b) Design pressure is less than 100psig
c) Vessel is in an intermittent service
d) Process fluid is either a Class 2 or Class 3 - ✔✔A
✔✔UT thickness readings will be taken on a vessel. Which of the following best
describes the process for taking readings at a specific examination point?
a) Take one reading and record
b) Take multiple readings and record the highest reading of the set
c) Take multiple readings and record the average of the set
d) Take multiple readings and record the lowest reading of the set
e) Take multiple readings and record the lowest reading or average of the set
, f) Take multiple readings and record the highest reading or average of the set - ✔✔E
✔✔CMLs should always be:
a) Measured with a digital UT instrument
b) Measured by someone certified to ASNT
c) Permanently marked on a drawing and/or on the vessel
d) Placed on each nozzle - ✔✔C
✔✔Who should be consulted about placement and number of CMLs for vessels with
suspected localized corrosion?
a) Corrosion Specialist
b) Engineer
c) Examiner
d) Inspector - ✔✔A
✔✔Which of the following conditions would justify fewer CMLs on a vessel?
a) Corrosion Rate is less than 0.010 ipy
b) Localize corrosion is expected
c) Uniform corrosion is expected
d) Vessel contains propane - ✔✔C
✔✔The number of CMLs can be eliminated or reduced if:
a) The consequence of vessel failure is low
b) The probability of vessel failure is low
c) Both the consequence and the probability of vessel failure is low
d) Either the consequence or the probability of vessel failure is low - ✔✔D
✔✔Who should be consulted is CMLs on a vessel is eliminated?
a) Corrosion Specialist
b) Engineer
c) Both the Inspector and the Engineer
d) Both the Inspector and the Corrosion Specialist - ✔✔A
✔✔Who should be consulted if CMLs on a vessel are substantially reduced?
a) Corrosion Specialist
b) Engineer
c) Both the Inspector and the Engineer
d) Both the Inspector and the Corrosion Specialist - ✔✔A
✔✔The NDE method called Alternating Current Flux Leakage is useful in finding:
a) MIC damage
b) Porosity in weld
c) Subsurface cracks
d) Surface-breaking cracks - ✔✔D
