Overview
ISO 49:1994 - "Malleable cast iron fittings threaded to ISO 7-1" specifies design, material, dimensional and performance requirements for malleable cast iron threaded pipe fittings used for the transmission of fluids and gases. The standard covers fittings intended to mate with threads made to ISO 7-1, for sizes 1/8 to 6. It defines material grades, coating and testing requirements, dimensional tolerances, and pressure/temperature suitability. For service outside the standard’s specified pressure and temperature limits, users are advised to consult the fitting manufacturer.
Key topics and technical requirements
- Scope and thread compatibility
- Fittings are designed for connection with threads per ISO 7-1 (jointing threads). Fastening threads (e.g., union nuts) follow ISO 228-1.
- Materials
- Primary material: malleable cast iron meeting ISO 5922.
- Specified grades include W400-05, W350-04, W350-10, B300-06 depending on design (whiteheart/blackheart).
- Alternative ferrous materials allowed for small fittings by agreement with purchaser.
- Protective coating
- Hot-dip zinc coating requirements: average areic mass ≥ 500 g/m² (approx. 70 µm); individual samples ≥ 450 g/m² (≈63 µm).
- Limits on trace elements and quality/continuity checks are specified.
- Dimensions and tolerances
- Standardized types and sizes are detailed in clauses for elbows, tees, unions, etc. Face-to-face and face-to-centre tolerances and laying lengths are provided.
- Thread alignment required within ±0.5°.
- Chamfer requirements: internal threads min included angle 90°, external threads 60°.
- Performance & testing
- Pressure/temperature ratings are specified (see standard’s table) and design test pressures are defined (hydrostatic test requirements).
- Leak and strength tests: options include hydrostatic test (≥ 20 bar) or pneumatic test (≥ 5 bar) with immersion detection.
- Material, coating and thread gauging/testing per referenced ISO methods.
Applications and who uses this standard
- Used by manufacturers, product designers, quality and test laboratories, procurement/specifiers, and pipeline/mechanical engineers to:
- Design and produce threaded malleable iron fittings for plumbing, heating, gas distribution and general fluid conveyance.
- Verify material, coating and dimensional conformity for safety and interchangeability.
- Establish acceptance criteria and testing procedures for batches and type-testing.
Related standards
Keywords: ISO 49:1994, malleable cast iron fittings, ISO 7-1 threaded fittings, hot-dip zinc coating, hydrostatic test, pipe fitting standard, design test pressure.
