ISO 23748:2016

Overview

ISO 23748:2016 - Aerospace series - O-ring grooves - Dimensions specifies groove geometries and tolerances for O‑rings used in aerospace static sealing applications. The standard covers both radial sealing (rod- or bore-mounted O‑rings) and axial sealing (internal or external pressure). It provides recommended groove dimensions, surface roughness limits, run‑out tolerances and drawing/presentation rules to ensure consistent sealing performance across aerospace components.

Key topics and technical requirements

• Scope: Groove dimensions for static aerospace seals - radial (rod or bore mounted) and axial (internal/external pressure).
• Configuration codes: Four configurations are defined
  • A: Radial sealing - rod housing (recommended)
  • B: Radial sealing - bore housing (not recommended)
  • C: Axial sealing for internal pressure
  • D: Axial sealing for external pressure
• Dimensional tables: Detailed tables for O‑ring groove parameters by O‑ring section diameters (1.80, 2.65, 3.55, 5.30, 7.00 mm) and multiple nominal diameters. Tables include groove width, depth, lead‑in chamfer, corner/edge radii and tolerances.
• Surface roughness: Specified roughness values (µm) for side surfaces, groove surfaces and inside diameters, with distinctions for pressure variation levels (≤5 MPa and >5 MPa).
• Tolerances and run‑out: Run‑out tolerances are provided (e.g., groove diameter d ≤ 50 mm: Y = 0.025 mm; d > 50 mm: Y = 0.05 mm) and dimensional tolerances reference ISO tolerance systems (e.g., ISO 286‑2).
• Designation and drawings: Requirements for designation, drawing presentation and use of ISO 3601‑1 O‑ring size codes are included to standardize engineering documentation.
• Notes: The edition explicitly adds “static applications” to title/scope and adopts ISO 3601‑1 size codes.

Applications and users

ISO 23748:2016 is used when designing and specifying O‑ring grooves for aerospace static seals, including:

• Hydraulic/pneumatic actuators and cylinders (rod and bore interfaces)
• Static flange seals, valve housings and pressure-retaining joints
• Aerospace component designers, mechanical and sealing engineers
• Seal manufacturers, quality & procurement teams, and CAD/drawing specialists Using this standard helps ensure interchangeability, reliable sealing performance and conformity with aerospace industry practices.

Related standards

• ISO 3601‑1 - O‑ring size codes (referenced for O‑ring codification)
• ISO 286‑2 - Tolerances (referenced for fit/tolerance values)
• Other ISO/industry standards on seal materials and dynamic sealing may be used in conjunction with ISO 23748:2016.

Keywords: ISO 23748:2016, O‑ring grooves, aerospace, groove dimensions, static sealing, radial sealing, axial sealing, ISO 3601‑1, surface roughness, tolerances.