456A Blueprint Reading, Weld Symbols & Joint Preparation 3

Question 1

What does a 'section view' on a fabrication drawing show compared to a 'plan view'?

Accepted Answer

A section view shows the internal geometry of a part as if it were cut along a specified plane; a plan view shows the external top-down view

Answer

A section view (cross-section) shows what a part looks like if it were sliced along a cutting plane indicated by a section line on the plan view. It reveals internal features, groove geometries, and dimensions that would be hidden in an external view. Section views are essential for understanding joint preparation requirements and weld access in complex structures.

Question 2

What does 'NTS' mean on a drawing and why does it matter for welders?

Accepted Answer

Not To Scale — dimensions must be taken from the written dimensions, not scaled from the drawing

Answer

NTS (Not To Scale) means the drawing has been intentionally or unintentionally reproduced at a different scale. Welders and fabricators must use the written dimension values and never measure from the drawing paper. Scaling a drawing can introduce errors from printing, copying, or digital scaling processes that can lead to incorrect joint preparation or weld sizes.

Question 3

On a structural steel drawing for a connection, what does 'PL 25 × 200 × 600 A36' describe?

Accepted Answer

A plate, 25 mm thick × 200 mm wide × 600 mm long, made from ASTM A36 steel

Answer

PL is the abbreviation for plate. The three dimensions are thickness × width × length in millimetres. A36 identifies the material specification (ASTM A36 carbon structural steel, 250 MPa yield strength). This type of notation is standard in Canadian structural steel drawings and tells the fabricator exactly what material to order and cut.

Question 4

What is a 'bill of materials' (BOM) on a fabrication drawing?

Accepted Answer

A table listing all components, their material specifications, sizes, quantities, and identifying marks for the fabricated assembly

Answer

The bill of materials (BOM) or parts list is a tabulated schedule on the drawing that identifies every component of the assembly with: item number (matching callout bubbles on the drawing), quantity, description, material specification (e.g., A36, A500 Gr C), and dimensions. It allows the fabrication shop to order materials accurately and track all components during assembly.

Question 5

What does the welding symbol 'melt-through' indicate on a drawing?

Accepted Answer

Complete penetration of the root from one side is required, producing a visible bead on the back side

Answer

The melt-through symbol (a filled semi-circle below the reference line, on the back side of a single-sided weld) indicates that complete penetration from one side is required and that a visible root bead is expected on the back surface. It is used for joints where welding access from only one side is possible but full penetration is required.

Red Seal Welder 456A Practice Test

Red Seal Welder 456A Practice Test

456A Blueprint Reading, Weld Symbols & Joint Preparation 3