ISO 5597:2018

Overview

ISO 5597:2018 - Hydraulic fluid power - Cylinders - Dimensions and tolerances of housings for single‑acting piston and rod seals in reciprocating applications - specifies preferred nominal dimensions and associated tolerances for hydraulic cylinder seal housings (piston and rod) used in reciprocating applications. The standard covers seal housing sizes for cylinder bores from 16 mm to 500 mm and rod diameters from 6 mm to 450 mm, and an additional compact range (for the 160 bar / 16 MPa ISO 6020‑2 compact series) covering cylinders 25–200 mm and rods 12–140 mm. ISO 5597:2018 addresses dimensional criteria only - it does not define seal design, materials or functional performance.

Key topics and technical requirements

• Seal housing dimensions and tolerances: preferred nominal sizes and dimensional tolerances for piston and rod seal grooves and housings.
• Axial length and radial depth: guidance on selecting axial groove length (L) and radial cross‑section depth (S); alternative sizes provided for most diameters and recommendations to consult seal manufacturers when using shorter lengths or when higher stresses are expected.
• Radial seal space tolerances: formulas and tables to determine allowable clearances between mating parts to maintain sealing integrity.
• Extrusion gap: criteria and recommendations for the metal gap behind seals; guidance to consult designers and seal manufacturers because extrusion gap varies with operating position and pressure.
• Surface roughness and material ratio: surface finish requirements for sliding and static sealing surfaces, plus recommended material ratio (Rmr) ranges; instruments conforming to ISO 3274 are recommended for measurements. The standard notes some designs may require minimum sliding surface roughness (e.g., ~0.1 µm Ra).
• Lead‑in chamfer: mandatory location and geometry guidance, including chamfer angle (20°–30°) and minimum axial length values.
• Reference and measurement standards: coordination with standards such as ISO 4287 (surface texture), ISO 286‑2 (fits/tolerances), and reference to ISO 3320 for tolerance conventions.

Applications and users

ISO 5597:2018 is intended for:

• Hydraulic cylinder designers and OEMs specifying seal housings and mounting features
• Seal manufacturers and suppliers defining compatible housings
• Quality/control and manufacturing engineers who machine bores, rods and grooves
• Purchasing and specification writers preparing procurement and component interfaces

Practical applications include design and production of hydraulic cylinders for industrial machinery, mobile equipment and any system using single‑acting pistons or rods in reciprocating service where standardized housing dimensions and reliable interchangeability are needed.

Related standards

• ISO 6020‑2 - mounting dimensions for single‑rod compact cylinders (16 MPa / 160 bar)
• ISO 4287 - surface texture: profile method
• ISO 3274 - surface roughness measurement instruments
• ISO 5598 - fluid power vocabulary
• ISO 3320, ISO 286‑2 - tolerance and fit conventions

Keywords: ISO 5597:2018, hydraulic fluid power, cylinder seal housings, rod seals, piston seals, dimensions and tolerances, reciprocating applications, surface roughness, extrusion gap, lead‑in chamfer.