ISO 15875-3:2025

Overview

ISO 15875-3:2025 - "Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE‑X) - Part 3: Fittings" is the 2025 second edition international standard that defines the characteristics and test parameters for fittings used in PE‑X piping systems for domestic hot and cold water and heating installations. The standard applies to fittings made from PE‑X, other plastics, or non‑plastic materials intended to connect to pipes conforming to ISO 15875-2, with joints assessed per ISO 15875-5. It specifically covers mechanical fittings and electrofusion fittings.

Key topics and technical requirements

ISO 15875-3 organizes requirements and test parameters across material, geometric, mechanical, physical and chemical aspects. Major technical topics include:

• Material characteristics for plastics and metallic fitting bodies, including thermal stability, degree of crosslinking and melt flow rate testing references (e.g., ISO 1133‑1).
• Mechanical characteristics for PE‑X fittings and for auxiliary parts made from other plastics or metals.
• Geometrical characteristics, such as nominal diameters, angles, threads and electrofusion socket dimensions.
• Physical and chemical testing (e.g., resistance aspects for copper alloys) and water‑quality influence considerations for components used in potable water systems.
• Sealing element requirements and performance testing.
• Performance requirements and marking (minimum marking obligations for traceability and safe use).
• Normative references and interoperability constraints with ISO 15875 series parts (notably ISO 15875‑1, ISO 15875‑2 and ISO 15875‑5).
• Notable update: inclusion of a 2 500 h at 95 °C confirmation test for certain materials introduced in this edition.

Practical applications and users

ISO 15875-3 is intended for anyone involved in the specification, manufacture, testing and approval of PE‑X piping system fittings, including:

• Manufacturers of PE‑X fittings and components (mechanical and electrofusion).
• Testing laboratories and conformity assessment bodies verifying compliance to ISO test parameters.
• System designers and specifiers for domestic water and heating installations relying on PE‑X piping systems.
• Installers and commissioning engineers who need to understand marking, joint compatibility and performance expectations.
• Regulators and consultants assessing suitability for potable water and heating applications.

Related standards

ISO 15875-3 is part of the ISO 15875 series and links directly to:

• ISO 15875-1 (general requirements and application classes)
• ISO 15875-2 (pipes)
• ISO 15875-5 (jointing and fitness-for-purpose) Other related ISO series for plastics piping systems are noted in the introduction (e.g., ISO 15874, ISO 15876).

For procurement and detailed test procedures, obtain the full ISO 15875-3:2025 text from ISO or your national standards body.