ISO 22391-3:2009

Overview

ISO 22391-3:2009 specifies requirements for fittings used in plastics piping systems made from polyethylene of raised temperature resistance (PE-RT), Type I and Type II, for hot and cold water installations within buildings (domestic and heating systems). The standard defines the characteristics, service classes, design pressures/temperatures, test parameters and methods that fittings must meet when used with pipes conforming to ISO 22391-2 and jointed per ISO 22391-5.

Key topics and technical requirements

• Scope of fittings covered: mechanical fittings (compression, crimped, flanged, flat-seat unions), socket fusion fittings, electrofusion fittings, and fittings with incorporated inserts.
• Material requirements: Rules for fittings made of PE-RT identical to pipe material and for fittings made from other plastics or metallic inserts. PE-RT fitting materials are assessed via injection-moulded tubular test pieces.
• Hydrostatic performance: Defined hydrostatic (hoop) stress tests using ISO 1167 test methods. Example control points:
  • PE-RT Type I: 9.9 MPa at 20 °C (1 h) and 3.4 MPa at 95 °C (1 000 h)
  • PE-RT Type II: 10.8 MPa at 20 °C (1 h) and 3.6 MPa at 95 °C (1 000 h)
• Physical and chemical tests: Melt mass/volume-flow (ISO 1133/1133-1), long-term hydrostatic strength evaluation (ISO 9080) and other material characterizations.
• Geometrical and sealing requirements: Dimensions for sockets (socket fusion/electrofusion), metallic fitting dimensions, and elastomeric seal material standards (EN 681 series, ISO 23711).
• System performance and marking: Requirements for overall system fitness for purpose, marking and traceability of fittings, and limits tied to design temperatures in ISO 22391-1.

Practical applications and users

ISO 22391-3 is used to ensure safe, reliable PE-RT piping systems for:

• Building services designers and specifiers selecting fittings for potable water and heating systems
• Manufacturers developing and approving PE-RT fittings, electrofusion or socket-fusion products
• Test laboratories and certification bodies performing hydrostatic and long-term performance tests
• Installers and plumbers verifying compatibility, jointing method (socket/electrofusion/mechanical) and marking
• Procurement teams and building code authorities that require compliance with international system standards

Related standards

• ISO 22391-1 - General (design classes, temperatures)
• ISO 22391-2 - Pipes (material and dimensional requirements)
• ISO 22391-5 - Fitness for purpose of the system
• Test and material standards referenced: ISO 1167, ISO 9080, ISO 1133, EN 681-1/2, ISO 23711

Keywords: ISO 22391-3, PE-RT fittings, plastics piping systems, hot and cold water installations, electrofusion fittings, socket fusion, hydrostatic test, melt flow rate, design pressure.