The story of the NAS523 rivet code is essentially the history of how the aviation industry moved from chaotic, localized labeling to a universal "language" for aircraft assembly.

: This final quadrant provides the shank length in 1/16-inch increments. A rivet marked with a in this corner would be 6/16" (or 3/8") long. Why This Matters

NAS523 Rivet Code is a standardized symbolic system used in aviation engineering drawings to provide precise instructions for fastener installation. It uses a single "crosshair" symbol divided into four quadrants, each representing specific rivet data. Quadrant Breakdown

IHS Markit (now S&P Global): The primary distributor of industry standards.
TechStreet: Another reputable source for purchasing engineering standards.
Document Management Systems: If you work for an MRO (Maintenance, Repair, and Overhaul) facility or an OEM, your company likely has a subscription to a standards database like Airframer or a similar internal library.

Length Code Table (Y value)

Length is measured under the head (grip length + clinch allowance).
Y = number of 16ths of an inch.

4. Diameter

The number following the material code represents the diameter of the rivet shank in thirty-seconds of an inch.

The SW quadrant dictates how the material should be prepared for flush or high-strength installation: D: Dimpled hole. C: Countersunk hole. DC: Dimpled top sheet and countersunk bottom sheet. D2C: Dimple the two top sheets and countersink the third. Technical Resources & Manuals

Southwest (SW) Quadrant - Special Operations: Indicates if the material needs specific preparation, such as dimpling or countersinking . D = Dimple C = Countersink D2 = Dimple both sheets

SW (Southwest - Lower Left): Details special methods or hole preparation required, such as dimpling (D) or countersinking (C). D2: Dimple both sheets. D2C: Dimple two top sheets and countersink the third. SE (Southeast - Lower Right): Specifies the rivet length in -inch increments. Example: A -6negative 6 code indicates a -inch length. Key Specifications & Reference

Rivet Code Pdf !new!: Nas523

The story of the NAS523 rivet code is essentially the history of how the aviation industry moved from chaotic, localized labeling to a universal "language" for aircraft assembly.

: This final quadrant provides the shank length in 1/16-inch increments. A rivet marked with a in this corner would be 6/16" (or 3/8") long. Why This Matters

IHS Markit (now S&P Global): The primary distributor of industry standards.
TechStreet: Another reputable source for purchasing engineering standards.
Document Management Systems: If you work for an MRO (Maintenance, Repair, and Overhaul) facility or an OEM, your company likely has a subscription to a standards database like Airframer or a similar internal library.

Length Code Table (Y value)

Length is measured under the head (grip length + clinch allowance).
Y = number of 16ths of an inch.

4. Diameter

The number following the material code represents the diameter of the rivet shank in thirty-seconds of an inch. The story of the NAS523 rivet code is

Southwest (SW) Quadrant - Special Operations: Indicates if the material needs specific preparation, such as dimpling or countersinking . D = Dimple C = Countersink D2 = Dimple both sheets IHS Markit (now S&P Global): The primary distributor