Case Study 1: Cutting Plane Line A dashed line with arrows points down across a valve's Top View.

Case Study 2: Internal Features Sectioning reveals hidden features as solid lines.

Basic Example: Full vs Half Section When to use a full section vs a half section on a symmetrical pipe.

Intermediate Example: Broken-Out Section A flange has a single keyway.

Advanced Example: Offset Section A block has staggered holes.

Basic Example: Material Identification A pump casing has uniform $45^\circ$ lines, bearing has thick/thin lines, seal has crossed diamonds.

Intermediate Example: Adjacent Parts Two identical steel plates are bolted together.

Advanced Example: Thin Materials A sheet metal casing is sectioned.