SIST EN 2908:2001

Overview

EN 2908:1994 defines the characteristics of bihexagonal, self-locking nuts with a deep counterbore manufactured in heat-resisting steel FE-PA92HT (A286) for aerospace use. The standard identifies mechanical classification as 1 100 MPa (at ambient temperature) / 650 °C, and specifies the form, function and intended application envelope for these high-temperature, high-strength fasteners. This document is intended for engineers, procurement specialists and quality teams working with aerospace fastener selection and certification.

Key Topics

• Product scope: Self-locking bihexagonal nuts with deep counterbore in FE-PA92HT (A286) for aerospace applications.
• Material: Heat-resisting steel FE-PA92HT (A286) - specified to ensure elevated temperature performance and sustained strength.
• Mechanical classification: Noted as 1 100 MPa (at ambient temperature) / 650 °C, indicating the design intent for high-strength and high-temperature service.
• Form and function: Bihexagonal geometry and internal self-locking feature combined with a deep counterbore to suit mating fastener assemblies used in aerospace structures.
• Compliance and use: Targets industry requirements for repeatable performance, resistance to vibration loosening, and compatibility with high-temperature environments.

Applications

These nuts are specified for aerospace applications where elevated temperature resistance and reliable locking performance are required. Typical practical values include:

• Use on high-temperature engine components, exhaust systems and hot-structure assemblies where A286-class materials are selected.
• Situations requiring a deep counterbore for clearance or recessing the nut into a component to control load distribution and geometry.
• Assemblies exposed to vibration and thermal cycling where self-locking behavior reduces the risk of fastener loosening.

Benefits and practical considerations:

• Thermal resilience: Material choice (FE-PA92HT / A286) provides improved performance at raised temperatures compared with standard stainless steels.
• High strength: The classification supports high-load fastening demands typical in aerospace structures.
• Design integration: Deep counterbore and bihexagonal form support secure seating in precision assemblies.

Related Standards

• Standards covering aerospace fasteners, bolt/washer compatibility and assembly processes are typically referenced alongside EN 2908:1994 when specifying a complete fastening solution.
• Material specifications and heat-treatment guidance for A286/FE-PA92HT components are complementary documents to consult for metallurgy and processing.

For procurement and engineering teams, EN 2908:1994 provides a focused baseline for selecting bihexagonal self-locking, deep counterbored nuts where high-temperature, high-strength performance is essential. Ensure compatibility with mating components and refer to applicable material and fastener installation standards when applying this specification.