: Aluminum Alloy (2024-T4, high strength, also an Icebox rivet)

is a National Aerospace Standard (NAS) document published by the AIA/NAS (Aerospace Industries Association) that defines the identification markings for solid rivets.

The PDF will usually include:

: Universal head rivets used in internal structures where flushness is not required. 2. Material Code (The Letter Identifiers)

4. Southeast (SE) Quadrant: Fastener Length and Welding Alternates

The system organizes information into four specific quadrants designated by compass directions:

Example: Y=8 → 8/16" = 1/2" length.

The NAS523 "Fastener Code" standard is an essential tool for engineering communication in the aerospace industry. It provides a clear, universal system for specifying fasteners, ensuring that designs are built accurately and safely. While the NAS523 PDF cannot be downloaded for free, purchasing the official standard from a certified provider is a worthwhile investment for any professional in the field.

The upper-left quadrant designates the core specification of the rivet, combining its head style and physical alloy into a compressed two-letter code.

Specifies a combination layout for joining thick and thin sheets together. 4. Bottom Quadrant: Grip Length

However, the full code printed on engineering drawings and in the follows a logical structure:

: Companies like Boeing or Piper may use proprietary variations (e.g., BAC codes) that cross-reference with NAS523 standards .

A typical NAS523 rivet part number looks like:

The NAS523 standard's true value is revealed through its widespread use in technical documentation:

100-degree countersunk flush head rivets (used on exterior aerodynamic skins). Step-by-Step Example: Interpreting a Code