ISO 15875-5:2025

Overview

ISO 15875-5:2025 - Plastics piping systems for hot and cold water installations - Crosslinked polyethylene (PE‑X) - Part 5: Fitness for purpose of the system - defines how to verify the fitness for purpose of PE‑X piping systems used for domestic water and heating within buildings. It sets the test parameters, performance characteristics and joint requirements for systems combining pipes (ISO 15875-2) and fittings (ISO 15875-3) under the design pressures and temperatures appropriate to the application class.

Key topics and technical requirements

• Scope and applicability

  • Covers PE‑X piping systems for hot and cold water (including domestic and heating systems).
  • Applicable to joints between pipes conforming to ISO 15875-2 and fittings conforming to ISO 15875-3.
  • Purchaser/specifier is responsible for selecting the correct application class and design conditions.

• Mandatory joint and system tests

  • Internal pressure test (ISO 1167 series) - uses a formula to derive hydrostatic test pressure from material stress values and design pressure; Table 2 provides derived pressures for application classes. Typical design pressures covered: 4, 6, 8, 10 bar; test temperatures up to 95 °C, test duration examples up to 1 000 h.
  • Thermal cycling test (ISO 19893) - verifies joint/assembly resistance to temperature changes.
  • Bending test (ISO 3503), Pull‑out test (ISO 3501) - for mechanical joint integrity under bending and longitudinal force.
  • Pressure cycling test (ISO 19892) and vacuum leaktightness test (ISO 13056).

• Test completeness and interchangeability

  • All required tests must be met for conformity.
  • Test results are specific to the tested combination of pipe and fitting and are not transferable to other combinations.

Applications and practical value

• Ensures long‑term reliability and safety of PE‑X piping systems used in:
  • Domestic hot and cold water distribution
  • Building heating systems (radiant heating, distribution circuits)
• Useful for:
  • Manufacturers (product design, type testing)
  • Test laboratories (type and system testing using specified ISO methods)
  • Specifiers, engineers and installers (selecting compatible components and application classes)
  • Certification and conformity assessment bodies

Related standards

• ISO 15875-1, -2, -3 (series for PE‑X materials, pipes and fittings)
• ISO 1167 (internal pressure testing)
• ISO 19892, ISO 19893 (pressure and temperature cycling)
• ISO 3501, ISO 3503, ISO 13056 (joint pull‑out, bending, vacuum tests)

Keywords: ISO 15875-5:2025, PE‑X, crosslinked polyethylene, plastics piping systems, fitness for purpose, hot and cold water installations, joint testing, thermal cycling, pressure cycling.