Non-Liquid Coatings

Question 1

What is hot-dip galvanizing?

Answer 1

Process of coating iron or steel with a thin zinc layer by passing the steel through a molten bath of zinc

Question 2

What is the temperature of a hot-dip galvanizing bath?

Answer 2

Around 820-860°F

Question 3

What does a hot-dip galvanizing bath result in?

Answer 3

Results in a metallurgical bond between zinc and steel

Question 4

The usual galvanized coating consists of what three distinct iron-zinc compounds?

Answer 4

• Gamma (75% zinc & 25% iron)
• Delta (90% zinc % 10% iron)
• Zeta (94% zinc & 6% iron)

• ETA (Outer layer) 100% not considered separate layer

Question 5

What are the two terms inspectors may hear when describing galvanizing?

Answer 5

• Heavy galvanizing
• Light galvanizing

Question 6

What is heavy galvanizing?

Answer 6

Can provide a complete coating of heavy zinc, both externally and internally, if required by specification

Question 7

What is light galvanizing?

Answer 7

Has significantly lower level of protection in corrosive environments, and often requires supplementary coatings for outdoor exposure

Question 8

What is the hot-dip galvanizing process?

Answer 8

• Surface preparation
• Fluxing
• Dipping
• Post treatments
• Inspection

Question 9

What is surface preparation for hot-dip galvanizing?

Answer 9

• Solvent cleaning (SSPC-SP1) and abrasive blasting may be specified
• Caustic cleaning
• Pickling

Question 10

What is caustic cleaning for hot-dip galvanizing?

Answer 10

The steel is immersed in caustic solution to remove dirt, oil, and grease from the surface of the steel

Question 11

What is pickling for hot-dip galvanizing?

Answer 11

The process where the item being prepared is immersed in a tank filled with either hydrochloric or sulfuric acid, which removes oxides and mill scale

Question 12

What is fluxing for hot-dip galvanizing?

Answer 12

Fluxing cleans the steel of all oxidation developed during pickling

Question 13

What are the two types of fluxing process?

Answer 13

• Immersion in a pre-flux solution that is slightly acidic and contains a combination of zinc chloride and ammonium chloride
• Passed through molten layer, top flux, that floats on top of the liquid zinc in the galvanizing

Question 14

How long do galvanizing hot-dips last?

Answer 14

In most cases dip lasts less than ten minutes

Question 15

Post treatments of hot-dip galvanizing may consist of what?

Answer 15

• Chromating
  -Phosphating
• Light rolling
• Roller leveling

Question 16

What is a condition that may occur if the aluminum contact of a hot-dip galvanizing bath. on which a flux blanket is used, is too high

Answer 16

Sometimes referred to as black spots

Question 17

What is sheradizing?

Answer 17

A metalizing alternative for fastener coatings. The fasteners are rotated in a drum for long period at moderate heat with zinc dust

Zinc powder in mixer provides uniform thickness

Question 18

What is aluminizing

Answer 18

Similar to hot-dip galvanizing except the bath metal is an aluminum-zinc alloy

Question 19

The major surface preparation steps for hot-dipped galvanizing include which of the following?
A. Solvent cleaning by caustic immersion
B. Acid pickling by hydrochloric or sulfuric acid
C. Post treatment using phosphate solutions
D. Roller leveling

Answer 19

A. Solvent cleaning by caustic immersion
B. Acid pickling by hydrochloric or sulfuric acid

Question 20

Annealing is a term used to define which process?
A. Of converting the galvanized coating into an alloy
B. Where the item is dipped into the acid bath
C. Where the item is dipped into chromating solution
D. Of increased aluminum contact in the zinc bath

Answer 20

A. Of converting the galvanized coating into an alloy

Question 21

You will be an inspector for a hot-dipped galvanized project. Which of the follow are likely reasons of the galvanized material>
A. Gross dross protrusions
B. Uneven drainage
C. Gross ash inclusion
D. Gross flux inclusion

Answer 21

A. Gross dross protrusions

C. Gross ash inclusion
D. Gross flux inclusion

Question 22

The development of a dull gray appearance in a freshly hot-dipped steel often occurs as a result of ?
A. Too thin a layer of zinc
B. High silicon steels
C. Old zinc in the bath
D. Non-fluxing the material

Answer 22

B. High silicon steels

Question 23

In the protective coatings industry, the application method known as thermal spray metalizing is which of the following?
A. Cold dipping of liquid metals
B. Centrifugal spraying of molten metals
C. Spraying molten metal on substrates
D. Applying metal with a plural component pump

Answer 23

C. Spraying molten metal on substrates

Question 24

Thermal spray coatings are most typically applied to _______.
A. High strength alloys
B. Iron (steel)
C. Fiberglass reinforced plastic (FRP)
D. Aluminum

Answer 24

B. Iron (steel)

Question 25

Which thermal spray application method provides a film with the least porosity?
A. Flame spray
B. Arc spray
C. Plasma spray
D. High-velocity oxyfuel (HVOF)

Answer 25

D. High-velocity oxyfuel (HVOF)

Question 26

Which standard defines the minimum level of surface cleanliness for thermal spray coatings in atmospheric exposure?
A. NACE 1/SSPC-SP 5 or ISO SA3
B. NACE 2/SSPC-SP 10 or ISO SA 2 1/2
C. NACE 3/SSPC-SP 6
D. NACE 8/SSPC-SP 14 or ISO SA 2

Answer 26

B. NACE 2/SSPC-SP 10 or ISO SA 2 1/2

Question 27

What is arc spray?

Answer 27

Electric heat source in thermal spray process. Relatively inexpensive, easy to learn, portable, and fairly simple to maintain. Low particle velocities enable high maximum coating thicknesses for a given materal

Question 28

What is flame spray?

Answer 28

Chemical (combustion) heat source in thermal spray process. heat and project the coating material with an oxy-fuel flame and a pressurized carrier gas jet

Question 29

What is plasma spray?

Answer 29

Electric heat source in the thermal spray process. This process is considered to be the most versatile of the thermal spray processes. During operations, gases such as argon, nitrogen, helium, or hydrogen pass through a gun. An electric arc disassociates and ionizes the gases. Beyond the nozzle, the atomic components recombine, giving off a tremendous amount of heat.

Question 30

What is thermal spray?

Answer 30

Wire or powder is melted by a flame or electricity and sprayed onto the substrate