Bolts, Screws, and Nuts - External Wrenching UNJ Thread, Inch - Design Standard
|Publication Date:||1 March 2021|
The scope of this SAE Aerospace Standard (AS) is to define the following dimensional requirements for double hexagon, hexagon head and tee headed bolts, and nuts with AS8879 UNJ inch series threads primarily for use in propulsion systems. Design requirements are based on UNJC threads for sizes 0.1640 and smaller and UNJF threads for sizes 0.1900 and larger.
a. Head configurations and dimensions (see 3.1)
b. Shank configurations and dimensions (see 3.2)
c. Geometric control (see 3.3)
d. Surface texture (see 3.4)
a. Configurations and dimensions (see 4.1)
b. Geometric control (see 4.2)
c. Surface texture (see 4.3)
Strength Classes Double hexagon bolt heads are shown in two configurations for up to 220 ksi minimum ultimate tensile strength and up to 260 ksi minimum ultimate tensile strength. Nuts configurations are for up to 260 ksi minimum. However, the ability of a design to achieve a given strength class will ultimately depend on the selected material, associated processing, and the specific geometry.
Dimensions and tolerances in this document are in inches, unless otherwise specified.
Plating and Coatings
Dimensions specified in this document apply after plating and before coating (e.g., dry film lubrication).
As defined by the Federal Cataloging System, thread sizes less than 0.1900 are referred to as screws and larger sizes are referred to as bolts. For the purpose of this document, the term bolt will be used for all sizes.
Appendices A and B contain basic part drawing templates for a double hexagon bolt and a double hexagon nut based on the recommendations of this standard. They are shown in SAE AS Part Standard formats but can be adapted for use in any drawing format.