SIST EN 3020:2008

Overview

SIST EN 3020:2008 is a European standard developed by CEN, specifying self-locking floating plate nuts designed specifically for aerospace applications. These nuts are made from heat-resistant steel FE-PA92HT (A286) and are silver plated to enhance their durability and corrosion resistance. Classified to withstand tensile strengths of 1,100 MPa at ambient temperatures and maintain performance up to 650 °C, this standard ensures the safety, reliability, and performance of fastening components used in the aerospace industry.

Key Topics

• Material Specifications
  The nuts are manufactured from heat-resistant steel FE-PA92HT (A286) conforming to EN 2399 and related aerospace alloy standards (EN 3638, EN 3639). This material provides excellent mechanical strength and heat resistance necessary for aerospace environments.

• Design and Configuration
  The standard defines the dimensional requirements, tolerances, and configuration of floating, two-lug self-locking plate nuts. The design permits a controlled radial float to accommodate slight misalignments during assembly, improving reliability under dynamic loads.

• Surface Treatment
  Silver plating, as specified in EN 2786, is applied to the nut element for corrosion protection and enhanced surface conductivity. The plating thickness is precisely controlled-5 to 15 µm externally and minimum 5 µm on threads (MJ 6 and above)-to ensure consistent performance without compromising thread tolerances.

• Classification and Performance
  These plate nuts are classified for a tensile strength class of 1,100 MPa at ambient temperature and are qualified to endure temperatures up to 650 °C. This classification ensures reliable performance even under high thermal and mechanical stress typical of aerospace environments.

• Marking and Identification
  EN 3020 mandates markings in compliance with EN 2424 to provide traceability, which is critical for aerospace safety and maintenance practices. The marking includes thread codes and the standard identification number.

Applications

• Aerospace Fastening Solutions
  SIST EN 3020:2008 nuts are essential components in aerospace assembly – used in aircraft structures, engines, and systems where high strength, thermal resistance, and locking reliability are critical.

• High-Temperature Environments
  Suitable for fastening parts exposed to elevated temperatures such as near engines, exhaust systems, or other heat-intensive aerospace machinery.

• Dynamic Load Adaptation
  The floating feature of these plate nuts supports vibration and dynamic load conditions common in flight, reducing the risk of loosening or failure over time.

• Corrosion Resistance
  Silver plating ensures these nuts maintain integrity and functionality in corrosive environments, enhancing the service life and safety of aerospace hardware.

Related Standards

• EN 2399 – Heat resisting steel FE-PA92HT bars for forged bolts, providing the base material specification.
• EN 2786 – Specifies electrolytic silver plating for aerospace fasteners ensuring corrosion resistance.
• EN 3004 – Technical specification for self-locking nuts with MJ threads in heat-resisting steel.
• EN 2424 – Aerospace product marking standard to guarantee identification and traceability.
• ISO 5855-2 – Defines limits for MJ threaded bolts and nuts, relevant for dimension and tolerance verification.

This standard plays a vital role in maintaining the highest quality and safety of aerospace fasteners. Compliance with SIST EN 3020:2008 ensures that floating, self-locking plate nuts deliver superior mechanical properties, resilience to temperature extremes, and consistent performance under demanding aerospace conditions. It is a critical reference for manufacturers, engineers, and quality assurance teams operating in the aerospace fastener supply chain.