Overview
EN ISO 6149-3:2007 / ISO 6149-3:2006 specifies the dimensions, design, test methods and performance requirements for metric light‑duty (L‑series) stud ends with ISO 261 metric threads and O‑ring sealing for hydraulic fluid power and general use. Adopted by CEN as EN ISO 6149-3:2007, this part of ISO 6149 covers both adjustable and non‑adjustable stud ends and the matching O‑rings.
Key topics and technical requirements
- Scope: Metric adjustable and non‑adjustable L‑series stud ends and O‑rings; applicable to hydraulic fluid power and general pressurized fluid systems.
- Dimensions & identification: Detailed dimensional specifications, identification marks and designation format (example: “Stud end ISO 6149-3 - M18 × 1,5”).
- Working pressure: Rated up to 40 MPa (400 bar) for non‑adjustable stud ends and 31.5 MPa (315 bar) for adjustable stud ends (permissible pressure depends on size, material and application).
- Performance tests: Burst and cyclic endurance (impulse) tests are required and shall be performed in accordance with ISO 19879. Conformance to dimensions alone does not guarantee required performance - manufacturers must test to demonstrate ratings.
- O‑rings: Dimensional and material guidance for O‑rings (default: NBR, hardness 90 ± 5 IRHD, per ISO 48 and acceptance criteria in ISO 3601‑3, grade N). Manufacturers should select alternative materials where different fluids or temperatures are used.
- Tolerances & fastener standards: Hex tolerances across flats per ISO 4759‑1 (product grade C); threads per ISO 261/ISO 965.
Practical applications and users
Who uses EN ISO 6149‑3:
- Hydraulic system designers and OEM engineers specifying ports and connectors
- Manufacturers of tube/hose fittings, stud ends and connectors
- Test laboratories validating burst and impulse performance
- Procurement and quality teams ensuring component conformity
- Maintenance and service engineers replacing hydraulic connectors
Practical benefits:
- Standardized metric threaded ports with O‑ring sealing simplify global sourcing and interchangeability
- Clear test and material guidance helps ensure safe operation at high working pressures
- Designation and identification rules aid traceability and correct installation
Related standards
EN ISO 6149‑3 is essential for anyone specifying or producing light‑duty metric stud ends with O‑ring sealing in hydraulic and pressurized fluid systems.
