Linings and special coatings

Question 1

In the coating industry, a lining is defined as?

Answer 1

The word ‘lining’ is used to describe a coating that is normally in immersion service

Question 2

Some resins used in reinforced linings include?

Answer 2

Polyester
Epoxy
Vinyl Ester

Question 3

What is the main feature that reinforcing adds to a resin?

Answer 3

Strength

Question 4

Describe wicking and how it may negatively affect a coating system?

Answer 4

Wicking is the ability of a liquid to travel along the fibers path, this can cause corrosion to the substrate, blisters or delamination of the system

Question 5

Describe normal surface preparation requirements for installation of a lining?

Answer 5

New surfaces - ISO SA3/NACE 1/SSPC 5 white metal blast cleaning.
Maintenance work - (may be) ISO SA 2.5/NACE 2/ SSPC 10 near white metal blast cleaning.
Water jetting is only used where a profile already exists, however there may be a need for waterjetting for cleanliness alongside abrasive blasting.

Question 6

What are antifouling materials and how do they work?

Answer 6

The purpose of antifouling paints is to either make the hull of the ship so distasteful the larva of the biofouling reject it as a home, or make the hull so slick that the larva cannot adhere

Question 7

The 3 main types of antifouling paints are?

Answer 7

Ablative (slowly dissolves to present a fresh layer)
Self Smoothing (similar to ablative but the rate of ablation is controlled and the surface becomes smoother during use)
Foul release (work on the principle of a non-stick surface)

Question 8

Types of fireproof coatings?

Answer 8

Cementitious- Made of lightweight cement and can be applied several inches thick
Intumescent - A substance that swells or bubbles up as a result of heat exposure, thus increasing in volume and decreasing in density.

Question 9

What are the best known characteristics of flouropolymer coatings?

Answer 9

Flouropolymer coatins are best known for their non-stick feature and also have excellent chemical and high temperature resistance.

Question 10

Describe the 2 broad categories of powder coatings?

Answer 10

Thermoplastic - Materials that soften when heated and return to their original hardness when cooled.
Thermosetting - Materials that harden when heated and retain their hardness when cooled

Question 11

What are the four distinct stages powders pass through when a heat source is applied?

Answer 11

The flow stage - Which occurs when the particles of powder begin to flow but are not fully liquid
Wetting stage - Which occurs when the particles of powder absorb more head, fully liquefy, and wet the surface
Gel stage - Which occurs when the particles of the powder begin to gel, converting into a solid
Curing stage - Allows for further changes to take place, permitting the powder to cure completely

Question 12

Advantages of plural component airless spray (over single piston airless spray)

Answer 12

Accurate mixing of materials without human element
Ability to spray very thick solvent free materials without thinners
The ability to spray materials with a very short pot life

Question 13

Disadvantages of plural component airless spray (over single piston airless spray)

Answer 13

Cost is much higher than a single piston pump
Higher education requirement for the mechanic
High voltage electricity is required for the heaters
Applicators job is more difficult with multiple hoses