ISO 6412-1:2017

Overview

ISO 6412-1:2017 - Technical product documentation - Simplified representation of pipelines - Part 1: General rules and orthogonal representation - defines rules and conventions for simplified pipe and pipeline drawings. It covers orthogonal (2D) projection methods used to represent rigid and flexible pipes, ducts (ventilation/air‑conditioning), fittings, supports and basic equipment in a consistent, legible way for technical documentation.

Key topics and requirements

• Flow lines: Pipes are represented by a single continuous thick flow line (central line); bends may be simplified (extended straight lines to vertices) or shown as arcs for clarity.
• Projection type: Focus is on orthogonal representation (right‑angle projectors). Isometric rules are covered in ISO 6412-2.
• Line types and usage: Specific line types and applications follow ISO 128‑20 conventions (main/secondary flow lines, leader and dimension lines, hidden features, centrelines).
• Spacing and thickness: Minimum spacing rules apply (e.g., space between parallel lines not less than twice the thickest line and at least 0.7 mm); minimum spacing between adjacent flow lines and other lines recommended at 10 mm.
• Lettering and symbols: Lettering should follow ISO 3098‑2; symbol presentation is coordinated with ISO 81714‑1.
• Dimensioning and tolerances: Dimensioning conforms to ISO 129‑1. Nominal pipe sizes may use the “DN” short designation (ISO 3545‑1); outer diameter and wall thickness references follow ISO 5261. Levels, slopes and bend radii/angles have prescribed depiction methods.
• Crossings and connections: Crossings without connection are normally shown without interrupting hidden flow lines; where required, hidden lines are interrupted with an interruption width not less than five times the continuous line thickness.
• Supplementary content: Examples and recommended practices (e.g., for slopes, coordinates of pipe ends, parts lists) are provided for clarity.

Practical applications

ISO 6412-1 is used whenever simplified, consistent pipe/pipeline representations are needed in:

• Piping and instrumentation diagrams, process plant documentation and layout drawings
• HVAC, ventilation and air‑conditioning schematic drawings (ducts substituted for pipes)
• Fabrication and installation drawings where simplified depiction speeds communication without full 3D modeling
• Technical manuals, equipment datasheets and parts lists where clarity of flow paths and connections matters

Who should use it

• Piping designers and engineers
• CAD technicians and draughtspersons producing piping schematics
• HVAC and process plant documentation specialists
• Technical authors, compliance officers and quality managers ensuring standardized drawings

Related standards

Relevant cross‑references include ISO 128 (presentation), ISO 129‑1 (dimensions), ISO 3098‑2 (lettering), ISO 3545‑1 (DN designation), ISO 5261 (profiles), ISO 5455 (scales), ISO 6412‑2 (isometric), ISO 14617 (graphical symbols) and ISO 81714‑1 (symbol design).