ISO 24568:2021

Overview

ISO 24568:2021 - "Aerospace - Metric series pipe coupling 8°30' up to 28 000 kPa dynamic beam seal - Technical specification" defines technical, inspection and procurement requirements for high‑pressure metric-series pipe couplings used in aerospace fluid systems. The standard covers dynamic beam seal couplings with an 8°30' sealing angle for nominal pressures up to 28 000 kPa, and for temperature ranges Type II and III as classified in ISO 6771. It sets out required characteristics, test methods, quality assurance and delivery requirements for manufacturers, purchasers and quality engineers.

Key topics and technical requirements

• Scope and limits
  • Metric series 8°30' dynamic beam seal couplings, up to 28 000 kPa, temperature ranges Type II & III (ISO 6771).
• Materials and dimensions
  • Conformity with product and semi‑finished material standards; chemical analysis or EN 10204 certificates required.
  • Dimensional inspection with appropriate measuring instruments.
• Surface and thread requirements
  • Surface roughness interpreted per ISO 1302; threads tested with GO gauges (tolerance class 4h6h).
  • Rolled threads preferred; specified maximum Ra (profile) and micro‑examination of thread flanks for rolled threads.
  • Surface defects (cracks, laps, folds, seams, pits) defined and controlled.
• Assembly and specimen preparation
  • Specimens assembled in accordance with prescribed methods; prior to qualification testing, couplings are assembled at maximum specified torque unless otherwise required (mixed torque assembly may be specified for some specimens).
  • Shaped parts machined with grain flow oriented in the fluid direction.
• Test and inspection methods
  • Requirements include proof, burst, leakage and fatigue/qualification testing; test fluids recommended (MIL‑H‑5606 for Type II, MIL‑H‑8446 for Type III), with water allowed for certain tests.
  • Pipe attachment (brazing, welding, mechanical) must not impair geometry or strength and shall be inspected (direct measurement, NDT).
• Quality assurance & procurement
  • Defines production and delivery batch concepts, qualification testing, AQL sampling (ISO 2859-1), acceptance/rejection criteria, quality control records and batch identification (Annex A).
• Preparation for delivery
  • Cleaning, preservation and packaging requirements to protect performance.

Practical applications and users

• Applies to designers, manufacturers and suppliers of aerospace hydraulic and fluid system fittings and tube assemblies.
• Used by procurement teams and quality assurance/inspection departments to specify accepted coupling characteristics and supplier compliance.
• Relevant for aerospace OEMs, MRO organizations, test laboratories and regulatory bodies involved in high‑pressure hydraulic line design, assembly and qualification.

Related standards (as referenced in ISO 24568)

• ISO 6771 (pressure and temperature classifications)
• ISO 6772 (impulse testing of hose, tubing and fitting assemblies)
• ISO 7137, ISO 7257, ISO 1302, EN 10204 and others cited for testing, materials, surface texture and documentation

Keywords: ISO 24568:2021, aerospace pipe coupling, dynamic beam seal, metric series, 8°30', 28 000 kPa, inspection and test methods, quality assurance, ISO 6771.