Overview
SIST ISO 7368:2021 - "Hydraulic fluid power - Two-port slip-in cartridge valves - Cavities" defines the geometrical requirements for cavities in which two‑port slip‑in hydraulic cartridge valves are mounted. The standard is strictly about dimensions, tolerances and surface requirements to ensure interchangeability of cartridge valves used in industrial hydraulic equipment. It does not specify performance parameters such as rated pressures.
Key topics and technical requirements
- Scope: Geometry-only requirements for cavities used with two‑port slip‑in cartridge valves (sizes include 06–16; sizes 15 and 16 were added in this edition).
- Dimensions and drawings: Detailed cavity layouts, figures and tables cover multiple nominal port diameters and configurations (including main system pressure‑relief valve variants).
- Tolerances:
- Positional tolerances for pin holes, screw holes and port holes: ±0.2 mm along x, y and z axes.
- General dimensional tolerances in accordance with ISO 2768‑1.
- Surface flatness requirement for sealing areas: 0.01 mm over 100 mm (see ISO 3601‑2).
- Surface finish:
- Surface roughness values (Rz) specified for sealing/chamfer areas; unspecified finishes default to Rz 63 µm.
- Surface texture indications referenced to ISO 1302 and ISO 4287.
- Sealing and O‑ring housings: Surface and dimensional alignment with ISO 3601‑2 for O‑ring housing dimensions.
- Thread and screw guidance:
- Minimum thread depth: 1.8 × screw diameter (D); recommended full thread depth 2•D + 6 mm.
- Recommended engagement for ferrous mounting: 1.25 • D.
- Identification statement: Standard provides an approved compliance statement for use in test reports, catalogues and sales literature.
Practical applications - who uses SIST ISO 7368:2021
- Hydraulic valve manufacturers designing two‑port slip‑in cartridge valves to be interchangeable with industry-standard cavities.
- Manifold and hydraulic manifold block designers engineering cavity layouts and port locations.
- OEMs and machine builders integrating cartridge valves into industrial equipment where consistent mounting geometry and sealing are required.
- Maintenance engineers and procurement teams verifying replacement valve compatibility and specifying cavity machining tolerances.
- Technical writers and catalog authors using the prescribed identification statement for conformity claims.
Benefits
- Ensures cross‑manufacturer compatibility and reduced redesign.
- Minimizes leakage and assembly issues by standardizing sealing surfaces and tolerances.
- Streamlines spare parts sourcing and reduces system downtime.
Related standards
Keywords: SIST ISO 7368:2021, hydraulic fluid power, two‑port slip‑in cartridge valves, cavities, interchangeability, manifold design, O‑rings, surface roughness, dimensional tolerances.