ISO 10146:2019

Overview

ISO 10146:2019 defines how to determine the expected strength of pipes made from crosslinked polyethylene (PE‑X) and crosslinked medium density polyethylene (PE‑MDX) as a function of time and temperature. The standard supplies reference lines (mathematical equations, graphs and tables) giving minimum long‑term hydrostatic strength for use in design calculations and lifetime assessments of PE‑X and PE‑MDX piping systems. It applies to pipes meeting the minimum degree of crosslinking specified in Clause 4 and to PE‑MDX within the density range 926–940 kg/m3 (per ISO 17855‑1:2014).

Key topics and technical requirements

• Reference lines and formulae: The standard provides analytical reference lines for temperatures between 20 °C and 95 °C and separate expressions for 110 °C. These describe log(time) as a function of temperature (K) and hoop stress (MPa), enabling interpolation and controlled extrapolation.
• Degree of crosslinking: Minimum crosslinking after production is required and quantified by gel content (ISO 10147). Typical minimums: peroxide and UV processes ≥70%, silane ≥65%, electron beam ≥60%.
• Extrapolation and activation energy: Temperature dependence is based on an Arrhenius approach with an activation energy of 110 kJ/mol. The standard lists extrapolation factors (k) to convert life at 110 °C to lower temperatures (e.g., k ≈ 4 at ≤95 °C, k ≈ 18 at ≤80 °C, k ≈ 50 at ≤70 °C, k ≈ 100 for <50 °C).
• Tabulated and graphical data: Expected hoop strength values for various temperatures and exposure times are tabulated (no safety/design factors included) and plotted for PE‑X and PE‑MDX.
• Conformance testing: Annex A details demonstration methods (pressure testing per ISO 1167‑1/2, long‑term hydrostatic testing per ISO 9080). At least 97.5% of experimental results should lie on or above the reference line. Specific temperature/time test points and required failure‑time distributions are defined.

Applications and users

• Pipe manufacturers and material suppliers: validate production batches and verify degree of crosslinking.
• Design and pressure‑rating engineers: calculate allowable hoop stress and predict service life of PE‑X / PE‑MDX piping in heating, potable water, and industrial applications.
• Specifiers, testing labs and regulatory bodies: use reference lines for compliance, quality assurance and warranty assessments.
• R&D teams: compare new formulations or crosslinking processes against agreed long‑term performance baselines.

Related standards

• ISO 9080 - long‑term hydrostatic strength by extrapolation
• ISO 10147 - estimation of degree of crosslinking (gel content)
• ISO 1167‑1 / ISO 1167‑2 - resistance to internal pressure test methods
• ISO 17855‑1 - PE material designation and density ranges

Keywords: ISO 10146:2019, PE‑X, PE‑MDX, crosslinked polyethylene, expected strength, time and temperature, hoop strength, long‑term hydrostatic strength.