ISO 21225-1:2018

Overview

ISO 21225-1:2018 - Plastics piping systems for the trenchless replacement of underground pipeline networks - Part 1: Replacement on the line by pipe bursting and pipe extraction - defines requirements and test methods for polyethylene (PE) pipes, fittings and installed systems used in trenchless pipeline replacement by pipe bursting and pipe extraction. It applies to both non‑pressure and pressure drainage/sewerage networks and to underground water and gas supply networks. The standard covers manufactured PE pipes (solid wall, co‑extruded layered, and coated pipes) as well as butt‑fusion and electrofusion jointing and PE fabricated/injection‑moulded fittings.

Key topics and technical requirements

• Scope and applicability: PE materials only; excludes other plastics (e.g., GRP). Applicable to manufactured pipes and the installed replacement system.
• PE pipe types:
  • Solid wall single‑layer PE pipes (nominal outside diameter, dn).
  • Co‑extruded layered PE pipes (total outside diameter, dn) with equal MRS rating across layers (see Annex A).
  • Coated PE pipes with a peelable contiguous thermoplastic outer layer.
• Jointing and fittings: Requirements for butt fusion and electrofusion joints, and for fabricated/injection‑moulded PE fittings.
• Design and material selection: Guidance on selecting appropriate PE materials and ancillary components for trenchless replacement projects.
• Installation practice and equipment: Covers preparatory work, storage/handling, inspection, lifting, fusion equipment, skids/rollers, winching/rod‑pulling, and dedicated pipe bursting and pipe extraction equipment.
• Inspection, testing and fitness for purpose: Process‑related inspection, pressure testing, disinfection, final inspection and documentation requirements to verify the installed system meets performance expectations.
• Annexes: Annex A on layered pipes (normative) and Annex B with pipe design considerations specific to pipe bursting and pipe extraction (informative).

Applications and users

ISO 21225-1 is intended for practitioners involved in trenchless renewal and replacement projects:

• Civil and pipeline engineers specifying trenchless replacement solutions
• Utilities and municipal asset owners (water, gas, sewerage)
• Trenchless contractors and installation crews using pipe bursting or pipe extraction techniques
• PE pipe and fittings manufacturers and quality managers
• Specifiers, procurement officers and standards committees preparing product/system specifications

Practical benefits include standardized material and jointing requirements, guidance on installation equipment and inspection/testing procedures, and improved confidence in the long‑term performance of trenchless PE replacement systems.

Related standards

Part of the ISO 21225 series (Part 2 covers off‑line replacement by HDD and impact moling). Normative references include related PE system standards such as ISO 4427, ISO 4437, EN 12201, EN 1555 and equipment standards ISO 12176‑1/2. These provide complementary requirements for PE pipeline construction and fusion equipment.