Piping drawing conventions: Which drawing style shows a pipe with two parallel lines representing the actual outside diameter and wall thickness rather than a single centerline?

Introduction / Context:
In drafting and CAD for piping, two common representation styles are used. Understanding when to use single-line versus double-line is essential for clarity, scale accuracy, and fabrication readiness.

Given Data / Assumptions:

• Pipes can be depicted schematically or with realistic wall thickness.
• We are distinguishing between representational conventions.
• Objective is to identify the style that explicitly shows diameter with two lines.

Concept / Approach:
Single-line drawings use a single line (often a centerline) to indicate pipe runs, suitable for schematics and diagrams. Double-line drawings use two parallel lines to show actual pipe outer diameter (and sometimes wall thickness), appropriate for scaled fabrication or coordination drawings where physical space, clearances, and interference checks matter.

Step-by-Step Solution:

Verification / Alternative check:
Open a CAD template for process piping: P&IDs use single-line; layout drawings for fabrication and clash detection use double-line models.

Why Other Options Are Wrong:

• Single-line: Shows only a path or centerline; does not depict diameter.
• Standard piping / Centerline piping: Nonstandard terms in this context; centerline implies single-line convention.

Common Pitfalls:
Mixing conventions in one sheet without a clear legend, causing misinterpretation by installers and reviewers.

Final Answer:
Double-line