IEC 81346-2:2019

Overview

IEC 81346-2:2019 is the second edition of a horizontal international standard that defines a harmonized classification scheme for industrial objects and the associated letter codes for classes. It supports consistent reference designations and generic type indications across all technical disciplines (electrical, mechanical, process, civil) and industry branches (energy, chemical, construction, automotive, shipbuilding, etc.). This edition refines the scheme to reflect an object’s inherent function, aligns class definitions with ISO 22274 and ISO 704, introduces a three‑level classification, and adds a separate scheme for spaces.

Key Topics

• Classification scheme design
  • Entry classes based on an object’s inherent function (stable over lifecycle).
  • A faceted, three‑level hierarchy that improves flexibility for designers.
• Letter codes for classes
  • Short, stable codes intended for use in reference designations (with IEC 81346‑1) and as generic type designations in specifications.
• Definitions and preferred terms
  • Each class is defined by its definition and given a preferred term; examples are provided where helpful.
• Separate classification for spaces
  • A dedicated scheme to classify rooms, areas and other spaces in installations and infrastructure.
• Horizontal applicability
  • Designed as a horizontal publication for use across technical committees and to support IEC Guide 108 principles.

Applications

IEC 81346-2:2019 is practical for organizations and professionals who need consistent, unambiguous identification of system elements across design, documentation and lifecycle activities:

• Design and engineering teams - to create standard reference designations and modular, cross‑discipline documentation.
• Technical committees and standards authors - to harmonize reference designation rules in new standards.
• Asset and configuration managers (PLM/PDM/CMDB) - for reliable class codes used in databases, maintenance records and BOMs.
• Specification writers and procurement - to use generic type codes in technical specs and tender documents.
• Systems integrators and contractors - to align documentation and ensure interoperability across trades and systems.

Practical benefits include improved traceability, clearer documentation, enhanced interoperability across disciplines, and reduced ambiguity during design, construction, operation and maintenance.

Related standards

• IEC 81346‑1 (reference designation construction rules)
• Other parts of the IEC 81346 series
• ISO 22274 (terminology/structure guidance)
• ISO 704 (terminology principles)
• IEC Guide 108 (horizontal standard principles)

Keywords: IEC 81346-2:2019, classification, reference designations, letter codes, inherent function, three-level classification, spaces classification, industrial systems, ISO 22274, ISO 704.