Full definition
International standard specifying dimensions, tolerances, and groove design for toroidal sealing rings (O-rings) in metric sizes. ISO 3601 is the metric complement to AS568B (the American standard using inch dimensions). Parts: ISO 3601-1 (O-ring inside diameters, cross-section diameters, and tolerances — covers ID from 0.74 to 658.88 mm), ISO 3601-2 (housing/groove dimensions for O-ring applications — static axial, static radial, and dynamic), ISO 3601-3 (quality acceptance criteria — surface defects, flash, parting lines), and ISO 3601-4 (O-ring material classification for common applications). The standard provides a complete system for specifying and designing O-ring seals: ring dimensions with tolerances, groove geometry (width, depth, surface finish), and squeeze percentages (typically 8-25% of cross-section diameter). For international projects and European-manufactured equipment, ISO 3601 metric sizes are standard. For North American equipment, AS568B dash numbers (inch) are standard. Cross-reference tables between the two systems are available. Per ISO 3601:2020 (latest revision). Most seal manufacturers (Parker, Trelleborg, Freudenberg) supply O-rings to both standards and provide cross-reference catalogs.