Overview
ISO 3458:2015 specifies a standardized test method for checking leak tightness of mechanical joints between fittings and plastic pressure pipes under internal pressure. It applies regardless of fitting design or material and is intended for assembled joints (not fusion-welded joints). The method defines the principle, required apparatus, specimen preparation, conditioning, test procedure, and the format of the test report.
Key topics and requirements
- Scope and principle
- Verifies leak tightness of assembled mechanical joints under an internal test pressure greater than the pipe’s nominal rating.
- Not applicable to fusion‑welded joints.
- Test parameters
- Parameters are supplied by the referring standard; if absent, default values from Annex A apply (see below).
- Pressure and temperature must be controlled: pressure within ±2% and temperature within ±2 °C.
- Apparatus
- Pressure source and measuring device capable of maintaining specified pressure for at least 1 h with ±2% accuracy.
- Typical test rig includes connecting elements, tested fitting(s), pipe pieces, endcaps, valves and supporting frame. Water bath is optional for leak detection.
- Test pieces and conditioning
- Test specimen: one or more joints with pipe(s) and fitting(s) of the size and quality intended for use.
- Components should ideally be aged 24 h after production before testing (shorter allowed for practical reasons; 24 h applies in dispute).
- Conditioning periods depend on pipe wall thickness:
- e ≤ 10 mm → 20 min
- 10 < e ≤ 20 mm → 60 min
- e > 20 mm → 120 min
- Procedure
- Fill specimen with water or air (remove air if water used).
- Apply specified temperature and conditioning, then increase pressure progressively to the test level.
- Monitor for loss of pressure or visible leakage; record failure if leakage occurs at the joint or within one pipe diameter from the joint.
- If pipe failure occurs beyond one diameter, repeat the test.
- Reporting
- Report must reference ISO 3458, include component IDs, nominal pressure class, free length, medium, period, pressure, temperature, leakage details, and test date.
Practical applications and users
- Used by manufacturers of plastic fittings and piping systems, independent testing laboratories, certification bodies, design and installation engineers, and specifiers to validate mechanical joint performance.
- Typical applications include water distribution, pressure fluid transport systems, and quality/conformity testing during product development, production control, and type approval.
Related standards
- The 2015 edition aligns with IEC/ISO directives and is prepared under the Vienna Agreement; it is aligned historically with EN 715:1994 as noted in the standard’s foreword.
Keywords: ISO 3458:2015, plastics piping systems, mechanical joints, leaktightness test, internal pressure, fittings, pressure pipes, test method.
Open preview (PDF)Plastics piping systems — Mechanical joints between fittings and pressure pipes — Test method for leaktightness under internal pressure
