308A Metal Types and Properties 3

Question 1

What type of sheet metal is required for kitchen exhaust hoods handling grease-laden vapours?

Accepted Answer

Minimum 18-gauge stainless steel (Type 304 or 316) for grease resistance and fire safety

Answer

Galvanized steel

Answer

Aluminum

Answer

Copper

Question 2

What is 'G90' coating designation on galvanized steel?

Accepted Answer

The zinc coating weight — 0.90 ounces of zinc per square foot of sheet (both sides combined)

Answer

The gauge of the steel

Answer

The grade of the steel

Answer

The guaranteed lifespan in years

Question 3

Why is Type 316 stainless steel specified instead of Type 304 for certain sheet metal applications?

Accepted Answer

Type 316 contains molybdenum which provides superior resistance to chloride and chemical corrosion

Answer

Type 316 is cheaper

Answer

Type 316 is lighter weight

Answer

Type 316 is easier to form

Question 4

What is 'terne-coated' steel and what was it historically used for?

Accepted Answer

Steel coated with a lead-tin alloy, historically used for roofing and architectural sheet metal

Answer

Steel coated with copper

Answer

Steel coated with zinc

Answer

Steel coated with aluminum

Question 5

What physical property of metal is described by 'ductility'?

Accepted Answer

The ability to be stretched, formed, or drawn into shapes without fracturing

Answer

Resistance to heat

Answer

The weight per cubic foot

Answer

The electrical conductivity

Question 6

What is the effect of cold rolling on sheet metal properties?

Accepted Answer

It increases hardness and tensile strength while reducing ductility and producing a smoother surface finish

Answer

It makes the metal thicker

Answer

It makes the metal softer

Answer

It has no effect on properties