5/16-18 Flat Head Socket Cap Screws

5/16"-18 flat head socket cap screws in USS coarse (UNC) thread, made from heat treated alloy steel with a black oxide finish. We stock 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/4", 1-1/2", 1-3/4", 2", 2-1/4", 2-1/2", 2-3/4", 3" lengths. They take a 3/16" hex key. Length is measured overall, including the head. Longer lengths are partially threaded (PT).

Specifications

Size: 5/16"-18 (USS coarse)
Lengths: 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/4", 1-1/2", 1-3/4", 2", 2-1/4", 2-1/2", 2-3/4", 3"
Hex key: 3/16"
Tap drill: F
Material: alloy steel, ASTM F835
Finish: black oxide
Strength: 145,000 psi minimum tensile strength (ASTM F835)
Head: 82° countersunk

Common Uses

Flush mounting
Machine plates and slides
Fixtures

FAQ

What hex key fits a 5/16"-18 flat head socket cap screw?
A 3/16" hex key (Allen wrench).

What tap drill do I use for 5/16"-18?
Use a F drill for a standard 75% thread.

Are button head socket screws as strong as socket head cap screws?
No. Button and flat head socket cap screws are made to ASTM F835, with a minimum tensile strength of 145,000 psi in 1/2" and smaller and 135,000 psi over 1/2". Their smaller socket also takes less torque, so use a socket head cap screw for high loads.

Free shipping on orders over $100, and orders placed before noon EST ship the same day. Purchase orders are accepted from government agencies, schools, hospitals, municipalities and companies with established credit with The Nutty Company, Inc.