ISO 12151-4:2007

Overview

ISO 12151-4:2007 establishes the general and dimensional requirements for hose fittings with ISO 6149 metric stud ends intended for hydraulic fluid power and general use. It covers carbon-steel hose fittings for nominal hose inside diameters from 6.3 mm to 38 mm (per ISO 4397). The standard defines design, manufacture, marking, designation and performance verification for metric stud-end hose fittings used with compatible hoses and ports sealed by O‑rings.

Key Topics and Requirements

• Scope and materials: Specifies carbon steel fittings by default; other materials may be agreed between manufacturer and user. Fits hoses sized 6.3–38 mm nominal ID (ISO 4397).
• Metric stud ends and threads: Stud-end threads and port interfaces conform to ISO 6149-2 (heavy-duty S series) or ISO 6149-3 (light-duty L series) and ISO 261 metric thread forms.
• Performance and testing:
  • Hose assemblies tested per ISO 6605 (no leakage/failure).
  • Fittings’ working pressure verified per ISO 19879.
  • Working pressure of an assembly = lower of pressures specified in ISO 6149 series or the hose specification.
• Dimensions and tolerances:
  • Detailed dimensional tables and figures for straight and 90° elbow stud fittings.
  • Hex across-flat tolerances per ISO 4759-1 (product grade C).
  • Surface roughness (Ramax) for machined surfaces = 6.3 µm unless otherwise specified.
• Finish and corrosion resistance:
  • Carbon-steel parts require plating/coating that passes a 72 h neutral salt spray test (ISO 9227), with defined exceptions for wear zones.
• Designation and marking:
  • Standardized alphanumeric designation format (example: Hose fitting ISO 12151-4 - SDE - LM18 × 12,5).
  • Fittings must be permanently marked with manufacturer name/trademark.
• Assembly guidance:
  • Annex A contains practical instructions for assembling fittings into ISO 6149-1 straight thread O‑ring ports (O‑ring handling, lubrication and protective caps).

Applications and Who Uses It

• Hydraulic system designers and OEMs specifying reliable hose-to-port connections in industrial and mobile hydraulic systems.
• Manufacturers of hose fittings and hose assemblies for ensuring dimensional interchangeability and test compliance.
• Quality, testing and procurement teams that require standardized designation, corrosion resistance and documented verification testing.
• Maintenance and assembly technicians using Annex A assembly guidance for O‑ring port connections. Practical uses include hydraulic power units, industrial machinery, mobile equipment, and general-pressure hose installations where metric stud-end O‑ring sealing is required.

Related Standards

• ISO 6149-2 / ISO 6149-3 (metric stud ends dimensions and tests)
• ISO 4397 (hose nominal inside diameters)
• ISO 6605 (hose assembly test methods)
• ISO 19879 (hydraulic connection tests)
• ISO 9227 (salt spray corrosion test)
• ISO 4759-1, ISO 261, ISO 5598

Keywords: ISO 12151-4:2007, hose fittings, ISO 6149, metric stud ends, hydraulic fluid power, hose assemblies, ISO 4397, ISO 6605, ISO 19879.