Overview
EN ISO 9974-3:2000 (ISO 9974-3:1996) defines dimensions, performance requirements and test procedures for stud ends with metal-to-metal sealing (type B) and ISO 261 threads. The standard covers extra-light (LL), light (L) and heavy-duty (S) series used for ports and stud ends in general use and fluid-power applications. It includes designation rules, material guidance and qualification tests required to demonstrate conformity.
Key points in the scope:
- Applies to stud ends with ISO 261 threads and metal-to-metal sealing (type B).
- Specifies dimensions, performance requirements and test procedures for LL, L and S series.
- Notes that these stud ends may be used up to specified working pressures but are not recommended for leak-free hydraulic designs if re-used.
Key Topics
- Dimensions and designation: Stud ends conform to the dimensional tables and figures in the standard and are designated with the format referencing the part (e.g. "Stud end ISO 9974-3 - M10 x 1,5 S").
- Materials: Stud ends are typically manufactured from low-carbon steel and plated. Test blocks are unplated and hardened to 45–50 HRC for qualification tests.
- Working pressures: Published guidance indicates maximum working pressures of approximately 10 MPa for LL series, 25 MPa for L series and 40 MPa for S series (actual permissible pressure depends on size, material and application).
- Sealing behaviour: Metal-to-metal sealing produces a machined sealing edge that is compressed at assembly and damages the port sealing face, making safe re-assembly and guaranteed leak-free reuse impractical.
- Qualification tests: The standard specifies burst and cyclic impulse tests (burst/working ratio, burst pressure tests, and a cyclic endurance impulse test requiring 1,000,000 cycles for qualification).
- Test torques: Qualification torques are defined in the standard (table 3) for sizes from M12 to M48; example test torques include M12×1.5 = 45 N·m and M48×2 = 800 N·m (values are for testing only).
Applications
EN ISO 9974-3:2000 is intended for designers, manufacturers and testing laboratories working on:
- Fluid-power connectors and fittings for pneumatic and hydraulic circuits (general use).
- Tube, pipe and hose fittings that use stud ends with metal-to-metal sealing.
- Product qualification, procurement specifications and conformity assessment for stud-end components.
Practical benefits include standardized interchangeability, defined performance criteria (burst and impulse), and clear designation and test-reporting requirements (Annex A provides a test data form).
Related Standards
Annex A of EN ISO 9974-3 is normative (test data form); Annex B is informative (bibliography). Use the standard to ensure compatible, tested stud ends for fluid-power and general-purpose connections.
