Material selection and corrsion control

Question 1

A pipestill condenser is experiencing corrosion due to deposition of ammonium chloride salts. What is a practical control measure?

Answer 1

Not replace tubes with SS NOT Clad the tubes YES Water wash

Question 2

Which monitoring technique provides accurate coorsion rates of equipment?

Answer 2

NOT corrosion probes NOT cathodes NOT corrosion coupons YES Thickness readings

Question 3

Which property influences a material’s resistance to brittle fracture?

Answer 3

NOT Strength NOT hardness YES toughness

Question 4

What environment can increase the likelihood of CUI?

Answer 4

NOT freshly painted surface NOT temp boven 175C YES high humidity

Question 5

A Cr-Mo pressure vessel is operating at 540C and is in contact with H2S. Which two degradation mechanisms could most likely affect this equipment?

Answer 5

YES sulfidation YES creep NO sensitization

Question 6

What four practical methods can be used to mitigate the risk associated with corrosion at injection points?

Answer 6

YES lower velocity YES design YES lined piping NOT downgrade materials of construction NO inspection

Question 7

Sensitization is caused by which of the following?

Answer 7

YES high T exposure NO brittle fracture NO quenching of materials in manufacture NO stress corrosion cracking

Question 8

Which three degradation mechanisms could occur in a mix of injection point?

Answer 8

YES localized corrosion NOT creep NOT pitting YES thermal fatigue NOT galvanic corrosion YES erosion-corrosion

Question 9

Which three primary variables are used to define correct procedures when mothballing equipment?

Answer 9

Climate, length of shutdown, cost of maintenance

Question 10

Which of the following is not a type of corrosion probe?

Answer 10

NOT linear polarization NOT electrical resistance YES hydrogen probe

Question 11

Which is not a contributing factor for brittle fracture?

Answer 11

YES hight T NO stress NO poor material toughness NO crack-like defects

Question 12

During the use of high pressure water jetting, which two variables need to be matched to the environment?

Answer 12

Angle of impingement, pressure

Question 13

At which stress/cycle combination would a mild steel likely fail?

Answer 13

345 MPa; 5*10^5 cycles

Question 14

Which is the most corrosive stream in an amine unit?

Answer 14

Hot rich amine

Question 15

A steam generator is producing 600 psi steam. The deaerator treating feed water fails. How will this affedt the boiler?

Answer 15

Corrosion will increase

Question 16

Choose the best sacrificial anode for an aboveground steel storage tank in contact with soil?

Answer 16

Mg

Question 17

For abrasive cleaning or spray operations, the local wind velocity must be:

Answer 17

Less than 15 mph (6.7 m/s)

Question 18

Which of the corrosive zones of a salt water pier experiences the most severe corrosion?

Answer 18

Splash zone

Question 19

Below what relative humidity does only minimal corrosion occur on carbon steel?

Answer 19

70%

Question 20

Which of the following are advantages to shop application?

Answer 20

Structures arrive in the field protected, work may be more carefully planned

Question 21

Which statements about shrouding prevent overspray?

Answer 21

1) Does not prevent overspray
2) Most likely will be a confined space entry
3) Eliminates dangers from lead and chromium pigments
4) Requires airless spray to be used
5) May be required to limit dust/debris or capture for its desposal

(2, 5)

Question 22

Repairs to coatings or linings are commonly caused by which of the following?

Answer 22

1) Defective materials provided by the manufacturer
2) Tools and welding rods stored in vessels
3) Vessels used as rain shelters
4) Incorrect materials ordered by Puchasing department
5) Incorrect coating specification

(2,3)

Question 23

One aspect of dry fall coating is:

1) Dries so that It is tack-free to the touch
2) Is dry when it can be handled and moved without damage
3) Dries very quickly and will not adhere to nearby surfaces

Answer 23

3

Question 24

Which aspects of a moisture cured coating is correct:

1) Will cure underwater
2) Is commonly used as wet H2S internal lining materials
3) may recquire a mist coat of water to achieve full cure in arid environments
4) only cures when the relative humidity is below 70%
5) recquires atmospheric moisture to cure properly

Answer 24

3 and 5

Question 25

One aspect of TSA is

1) Is commonly used in acid treating units
2) can be applied over poorly prepped rusting substrates
3) cures by absorbing moisture from the air
4) recquires an abrasive blasted cleaned substrate wo white metal or near white cleanliness

Answer 25

4

Question 26

FRP linings are commonly used for which application?

Answer 26

storage tank bottoms

Question 27

Three advantages of sacrificial anode systems include:

1) min maintenance costs
2) simple to install
3) may recquire large number of anodes
4) limited output
5) practical with low resistance electrolytes only
6) independent of a power source

Answer 27

1,2 and 6

Question 28

Because the backfill around an impressed current anode is an electrically donductive material, what design variable does it reduce?

Answer 28

anode-to-ground resistance

Question 29

Which of the following sacrificial anodes has the largest energy contect?

Answer 29

Al

Question 30

Which three are advantages of impressed current system?

1) use is not resistricted by the resistivity of the electrolyte
2) the use of rectifiers provide a variable output, giving the system more flexibility
3) requires careful design consideration
4) can be used to protect even bare carbon steel structures
5) requires frequent attention and inspection
6) requires a power source

Answer 30

1, 2 and 4

Question 31

Which two selections are advantages of an impressed system for new storage tanks that are equipped with a Release Prevention Barrier?

Answer 31

Uniform current distribution across the bottom, no interference problem

Question 32

A Basic corrosion cell requires four key elements. If one of these elements is missing, corrosion will not occur

Answer 32

Metal path, anode, cathode, electrolyte

Question 33

Three materials that are used for impressed current anodes include:

Answer 33

conductive polymer, platinum, scrap iron and steel