Which thickness defines plates?

• A. PLATES ARE DEFINED AS >= 1/4 IN THICKNESS
• B. PLATES ARE DEFINED AS <= 1/4 IN THICKNESS
• C. SHEETS ARE DEFINED AS >= 1/4 IN THICKNESS
• D. SHEETS ARE DEFINED AS <= 1/4 IN THICKNESS

Answer: (A)

Thickness separates plate from sheet in metalwork. A plate is defined as a flat piece with thickness at least 1/4 inch, which is why thicker flat stock is labeled as plate and thinner stock as sheet. This cutoff reflects how the material behaves in forming, welding, and carrying loads—thicker pieces have more rigidity and structural applicability, fitting the plate category. In practical terms, a piece that is 1/4 inch or thicker is treated as plate, while thinner pieces fall under sheet metal.