Overview
ISO 2974:2018 defines the dimensional and functional requirements for 60° female cones used in high‑pressure fuel injection components on diesel (compression‑ignition) engines. The standard covers externally threaded 60° female cones intended for use with high‑pressure fuel injection pipe assemblies and specifies geometries, tolerances, surface finishes and designation rules to ensure interchangeability between injectors, pumps, rails and pipe assemblies.
Key scope limits:
- Integral female cones: for pipe outside diameters up to and including 12 mm (see Table 1).
- Fabricated female cones: for pipe outside diameters up to and including 9 mm (see Table 2).
The document references figures (Figures 1–7) and tables that detail the cone shapes, thread relationships and assembly interfaces.
Key Topics and Requirements
- Dimensions and tolerances: Precise cone geometry, reference diameters and relationships to the external thread are specified (Figures 1–7; Tables 1–2). Unspecified minor details may be left to the manufacturer’s choice.
- Integral vs. fabricated cones: Definitions and acceptable shape variations (integral cones may use Shapes A/B/C; fabricated cones include loading sleeves and connector nuts).
- Threading and gauges: External threads must allow the GO‑gauge to be screwed up to the plane defined by dimension T. Thread tolerance classes are defined (e.g., 6g for external threaded end‑connections; connector nuts use 6H where noted).
- Surface texture: Surface roughness indications follow ISO 1302 best practices as corrected in this edition.
- Materials and hardness: Material and heat treatment are specified according to intended use. To ensure proper sealing by plastic deformation of the pipe end, the female cone should be at least 50 HV harder than the maximum hardness of the pipe connection end; tightness through initial and repeated assemblies must be proven.
- Designation rules: Standardized naming format (e.g., “Integral female cone ISO 2974 A 10 – M22 × 1,5”) supports clear product identification.
Applications and Users
ISO 2974:2018 is used to achieve interchangeability, reliable sealing and manufacturing consistency in:
- Diesel injector, fuel pump, common‑rail and rail manufacturers
- High‑pressure fuel pipe assembly suppliers and connector makers
- OEMs, design engineers, quality and inspection teams (gauging, tolerancing)
- Aftermarket and maintenance operations for verification of connector compatibility
Practical benefits include reduced assembly leaks, consistent supplier interchangeability, and clear specification for procurement and testing.
Related Standards
- ISO 13296 - high‑pressure fuel injection pipe assemblies (pipe end forms referenced)
- ISO 1302 - surface texture specification
- ISO 261 / ISO 3508 - thread and thread run‑out requirements
Use these related standards in conjunction with ISO 2974:2018 for complete design and inspection workflows.
