For a complete list of material codes and head styles, technicians typically refer to the full NAS-523 Standard PDF or specialized guides like those found on Scribd and Studylib . Unit of Measurement Example Code Length Hole Prep D (Dimple), C (Countersink)
The NAS523 standard defines a universal shorthand code used on engineering drawings, blueprints, and Process Specification (Process Spec) documents. Instead of writing out lengthy descriptions for every single fastener on a blueprint—such as the rivet material, diameter, countersink angle, and head style—engineers use a standardized four-quadrant cross symbol or a linear alphanumeric string.
While legacy drawings heavily utilize the graphical cross symbol, modern Computer-Aided Design (CAD) systems and digital Product Lifecycle Management (PLM) databases often convert the NAS523 symbol into a linear text string for easier searchability. A linear code might look like this: NAS523 : The governing standard. AD : 2117-T4 Aluminum alloy material. 4 : 4/32" (1/8") diameter. 6 : 6/16" (3/8") length. C : Countersunk installation requirement. Why You Need the Official NAS523 Rivet Code PDF
The NAS523 code is visually represented as a four-cornered symbol (often resembling a crosshair or divided box) placed on blueprints. Each corner represents a different aspect of the fastener: nas523 rivet code pdf
The standard assigns a "dash number" to a specific combination of material and head style.
A NAS523 PDF decodes the shorthand engineers use on blueprints. You will often see letters like , D , or DD next to a rivet callout. The PDF explains these critical material codes:
When you look at an NAS523 part number (e.g., ), the code breaks down as follows: For a complete list of material codes and
: 7050 Aluminum (excellent corrosion resistance and high strength).
This lower-left quadrant provides specific dimpling or countersinking instructions for the hole preparation.
Because National Aerospace Standards are copyrighted engineering documents, they are typically not available for free legally on the public internet. To ensure you are using the most up-to-date, legally compliant revision for aviation maintenance or manufacturing, utilize the following channels: While legacy drawings heavily utilize the graphical cross
Typically indicates the rivet material or alloy type.
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: 2024-T4 Aluminum (high strength, also an "icebox" rivet).
100-degree countersunk flush head rivets (used on exterior aerodynamic skins). Step-by-Step Example: Interpreting a Code