Overview
IEC TR 63431:2025 - "Optical fibre cables - Microduct technology - Guidance" (Edition 1.0, 2025‑09) is a Technical Report from the IEC that provides practical guidance for adopting microduct technology in optical communications networks. It supplements the microduct sections of the IEC 60794‑5 series and documents current products, practices and considerations for design, installation and maintenance of microduct systems. Microducts are small, flexible tubes (typically ≤ 20 mm OD) used to install optical fibres by blowing, pushing or pulling.
Key Topics
- Microduct types and assemblies: definitions and examples of outdoor vs indoor microducts, single thick‑walled, bundled, flat formed bundles, protected vs unprotected microducts.
- Design and dimensions: guidance on microduct sizes, standard dimension ratio (SDR), OD/ID considerations and packaging.
- Installation methods: practical guidance for blowing applications, pushing, pulling and surface/aerial mounting.
- Mechanical and environmental properties: burst pressure, tensile behaviour, temperature performance, post‑shrinkage due to tension or temperature, and long‑term pressure testing.
- Identification and colour coding: recommended colour codes (RAL and IEC 60757 references) and marking practices for easy identification in networks.
- Testing, storage and delivery: installation performance tests, test rig examples, packaging, transport and storage advice.
- Repairs and maintenance: repair techniques (e.g., gel‑wrap kits), repair scenarios and recommended practices for field repair of microducts.
- Accessories and connectors: common practice of push‑fit connectors and implications when connecting dissimilar duct sizes.
- Informative annexes: associated documents, ITU‑T references and conference papers helpful for deeper study.
Applications
IEC TR 63431:2025 is aimed at practical deployment of microducts in:
- Broadband network operators and ISPs planning ducted or blown fibre installs
- Cable manufacturers and microduct suppliers designing products to fit network needs
- Installation contractors and field engineers performing blowing/pushing/pulling operations
- Utilities, municipalities and property developers specifying direct bury (DB), duct‑installed (DI) or in‑building microduct systems
- Standards writers and consultants aligning procurement and testing procedures
Related standards
- IEC 60794‑5 (Microduct cabling for installation by blowing) - normative complement
- IEC 60794‑1‑1 (Generic specification - General)
- ITU‑T recommendations (referenced in Annex A) - useful for interoperability and detailed blown‑fibre guidance
This Technical Report is practical, product‑focused guidance for anyone specifying, installing or maintaining microduct optical fibre systems and helps ensure reliable, maintainable microduct deployments.