Corrosion Under Insulation - CUI Flashcards
- CUI is caused by:
A. water trapped under insulation
B. water trapped under insulation or fireproofing
C. trapped water reaching the water’s boiling at the metal surface
D. water reacting with insulation to form a strong corrosive acid
B. water trapped under insulation or fireproofing
- Concerning CUI which of the following are true?
A. Corrosion pattern is usually uniform corrosion
B. Corrosion rate increases as temp increases up to where water rapidly vaporizes
C. The location of corrosion is always very predictable
D. Corrosion does not occur above 212F (water’s boiling point)
B. Corrosion rate increases as temp increases up to where water rapidly vaporizes
- CUI is a possibility on insulated Carbon Steel equipment that operates between:
A. 10 to 350F
B. 25 to 250F
C. 140 to 350F
D. 280 to 350F
A. 10 to 350F
- CUI is a possibility on insulated austenitic 300 Series SS equipment that operates between:
A. 10 to 350F
B. 25 to 250F
C. 140 to 350F
D. 280 to 350F
C. 140 to 350F
- CUI is a possibility on insulated Duplex SS equipment that operates between:
A. 10 to 350F
B. 25 to 250F
C. 140 to 350F
D. 280 to 350F
D. 280 to 350F
- CUI is a possibility on insulated 400 Series SS equipment that operates between:
A. 10 to 350F
B. 25 to 250F
C. 140 to 350F
D. 280 to 350F
A. 10 to 350F
- CUI occurring on 300 Series and Duplex SS equipment is actually caused by what type of corrosion mechanism?
A. Amine Cracking
B. Chloride SCC
C. Fiber fretting
D. Galvanic corrosion
B. Chloride SCC
- CUI is an inspection concern for insulated vessel that operates at 500F and:
A. is in an intermittent service
B. is made of stainless steel
C. is made of low chromes
D. have poorly maintained insulation
A. is in an intermittent service
- Which of the following insulated equipment is most likely to experience CUI?
A. CS vessel that operates continuously at 375F
B. CS vessel that operates continuously at -20 F
C. CS vessel with with operating temp of 600F but it is in an intermittent service
D. CS vessel that operates at cyclic temperatures ranging between 375F-600F
E. 300 SS vessel that operates continuously at 100F
C. CS vessel with with operating temp of 600F but it is in an intermittent service
- CUI can be more aggressive when:
A. The temperature is lowered.
B. Using fiberglass insulation
C. the insulation sheathing is made from aluminum
D. chlorides leach out of the insulation
D. chlorides leach out of the insulation
- Which of the following is NOT a common location for CUI on piping?
A. bolted on pipe shoes
B. First few feet of horizontal pipe attached to a bottom of a vertical pipe run
C. Insulation terminations
D. Piping spec breaks
E. Steam tracing tubing penetrations
D. Piping spec breaks
- Which of the following is a common location of CUI on piping? *This may have more than one correct answer, please select all answers that apply
A. vibrating piping systems
B. piping with insulation jacket seams on top of line
C. above insulation support rings on vertical vessels
D. piping or equipment near a cooling water tower
E. 300 series SS with fiberglass insulation
A. vibrating piping systems
B. piping with insulation jacket seams on top of line
C. above insulation support rings on vertical vessels
D. piping or equipment near a cooling water tower
- Which type of older insulation has been known to contain a high level of chlorides?
A. Asbestos
B. Calcium silicate
C. Fiberglass
D. Mineral wool
B. Calcium silicate
- CUI on Carbon Steel or low-alloy materials can appear as:
A. Cracking
B. general wall loss
C. localized wall loss
D. localized pitting or localized wall loss
D. localized pitting or localized wall loss
- CUI on 300 Series SS materials can appear as:
A. Cracking
B. general wall loss
C. localized pitted or localized wall loss
D. cracking or pitting
D. cracking or pitting
