Overview
EN ISO 22391-3:2009/A2:2021 is the CEN-adopted amendment (A2, Oct 2021) to ISO 22391-3 (Part 3: Fittings) for plastics piping systems for hot and cold water installations using polyethylene of raised temperature resistance (PE-RT). This amendment updates definitions, materials, test requirements and adds new normative references. It is intended to be published as a national standard across CEN members without alteration.
Key topics and technical requirements
- New and revised definitions
- Clarifies joint types: compression fitting, radial press fitting, axial press fitting, and push‑fit fitting (including notes on internal supports and sealing elements).
- Permitted metallic materials
- Metallic fittings for use with ISO 22391 components are limited to copper alloys or stainless steel alloys, defined by an applicable standard or regulatory document.
- Appearance and dimensional requirements
- Appearance criteria for plastic and metal fittings (surface finish, absence of defects).
- Dimensional measurement standards: plastic fittings - ISO 3126; metal fittings - ISO 2768‑1 and/or ISO 22081.
- Minimum wall thickness for copper-alloy fittings
- Annex A (normative) sets minimum wall thickness measurement rules and refers to specific measurement points; values are specified in the standard (see Annex A).
- Physical and chemical tests
- Plastics: Melt mass flow rate (MFR) comparison per ISO 1133‑1; for PE‑RT the T (190/5) condition applies and the MFR difference limit is 30% between compound and injection‑moulded fitting.
- Metals: Requirements for stress corrosion resistance and dezincification-hardness criteria and testing per ISO 6506‑1, ISO 6509‑1, and ISO 6957 as applicable.
- Cast alloy tightness test (new Clause 12)
- Cast fittings must be leak‑tested after machining; a recommended method is immersion in water while applying compressed air at ≥ 0.5 MPa (5 bar) to detect bubbles (leaks).
- Updated normative references
Applications and users
This amendment is relevant to:
- Manufacturers of PE‑RT fittings (design, tooling, material selection, quality control)
- Test laboratories performing MFR, corrosion, dezincification and tightness testing
- Specifiers and procurement teams drafting product requirements and compliance clauses
- Plumbing engineers, installers and regulators who rely on harmonized requirements for safe hot and cold water systems
- Standards bodies and conformity assessment organizations implementing CEN adoption
Related standards (examples)
Keywords: EN ISO 22391-3:2009/A2:2021, PE‑RT fittings standard, plastics piping systems, hot and cold water, compression fitting, press fitting, push‑fit, dezincification, melt mass flow rate, cast alloy tightness test.
