308A Blueprint Reading for Sheet Metal 3

Question 1

What is the standard line type used for dimension lines on a sheet metal drawing?

Accepted Answer

Thin solid lines with arrowheads at each end and the measurement written above or in the middle

Answer

Dimension lines are thin solid lines with arrowheads or tick marks at each end where they meet extension lines. The measurement value is placed above or in a break in the line.

Question 2

What does the symbol '∅' mean when it appears before a number on a sheet metal drawing?

Accepted Answer

Diameter of a circular feature

Answer

The ∅ symbol indicates diameter. When placed before a dimension (e.g., ∅12"), it means the measurement is the diameter of a circular feature such as a round duct, hole, or fitting.

Question 3

What is a 'shop drawing' versus a 'contract drawing' in sheet metal work?

Accepted Answer

Contract drawings are the engineer's design intent; shop drawings are the contractor's detailed fabrication drawings showing how to build it

Answer

Contract (design) drawings show the engineer's intent — duct sizes, locations, and system requirements. Shop drawings are prepared by the sheet metal contractor showing exact fabrication details, fittings, and assembly sequences.

Question 4

What does the abbreviation 'TYP' mean when it appears next to a dimension on a drawing?

Accepted Answer

Typical — this dimension applies to all similar features on the drawing

Answer

TYP (Typical) means the noted dimension or detail applies to all similar features or conditions on the drawing. It avoids the need to repeat the same dimension at every identical location.

Question 5

What information does a 'duct schedule' provide on a drawing set?

Accepted Answer

A table listing duct designation, size, gauge, insulation, liner, pressure class, and sealing requirements for each duct section

Answer

A duct schedule is a tabular summary listing every duct designation with its size, material, gauge, insulation requirements, internal liner specifications, pressure class, seal class, and leakage test requirements.

Red Seal Sheet Metal 308A Practice Test

Red Seal Sheet Metal 308A Practice Test

308A Blueprint Reading for Sheet Metal 3