FF-S-86 — Screw, Cap, Socket-Head
FF-S-86 covers socket-head cap screws with hexagon or spline internal drive recesses, used across general, high-temperature, high-strength, and corrosive-environment applications. It's one of the most actively maintained federal fastener specifications, with Revision J issued April 1, 2025.
At a Glance
Overview
FF-S-86 covers socket-head cap screws — high-strength fasteners with a cylindrical or countersunk head and an internal hexagon or spline drive recess, allowing high installation torque in confined or recessed spaces where a wrench can't reach an external head. It's one of the more actively revised federal fastener specifications: the current Revision J was published April 1, 2025, superseding Revision H (7 June 2021).
The specification draws its terminology and general dimensional framework from ASME B18.12 and its socket/hex-key geometry from ASME B18.3, while adding the material, finish, and quality requirements specific to federal procurement. Recent revisions have progressively phased out legacy configurations and hazardous finishes: Types III, V, VII, and IX (older screw types) were deleted, with buyers directed to evaluate Types IV, VI, and VIII as replacements, and cadmium/hexavalent-chromium coatings are now marked obsolete for new designs in favor of zinc-nickel or hexavalent-chromium-free zinc plating.
- Materials include alloy steel, austenitic corrosion resistant steel, Nickel Alloy 718 (with a distinct Navy shipboard material call-out per API 6ACRA), and silicon bronze.
- Part identification can follow a non-government or military part-numbering standard (e.g. NAS1351 or MS24672) or, optionally, ASME B18.24 — the supplier must specify which system is in use.
Material Options
FF-S-86 covers a range of base materials for different strength and environment requirements.
Finish Options
| Finish | Governing Spec | Note |
|---|---|---|
| Cadmium Plate | SAE AMS-QQ-P-416, Type II, Class 2 | Obsolete for new designs; hazardous substance |
| Zinc-Nickel | Section 3.3.5 | Approved cadmium replacement with design authority approval |
| Zinc Plate | ASTM F1941/F1941M, Class Fe/Zn 8 | Hexavalent-chromium-free conversion coating; requires hydrogen embrittlement bake |
Manufacturing & Quality Notes
Type I (1936-series) cylindrical socket head cap screws are obsolete for new designs; Types III, V, VII, and IX are similarly deleted, with Types IV, VI, and VIII recommended as replacements.
Zinc-plated alloy steel screws receive a 23-hour bake at 375°F ± 25°F, started within one hour of leaving the plating bath, to relieve hydrogen embrittlement.
Nickel Alloy 718 for Navy shipboard applications is sourced to API Standard 6ACRA material designations rather than the standard aerospace-grade material call-out.
Discontinuity limits for cylindrical and flat countersunk heads are defined separately, with all discontinuities measured perpendicular to the indicated surface.
FF-S-86 — Frequently Asked Questions
Is cadmium plating still allowed on FF-S-86 screws?
Cadmium coatings and coatings containing hexavalent chromium are marked obsolete and should not be used for new designs — zinc-nickel plating is the recommended cadmium replacement, subject to design authority approval.
What socket types does FF-S-86 cover?
Hexagon socket and spline socket head configurations, per ASME B18.3 geometry, with several historical "Type" designations (I, III, V, VII, IX) now deleted in favor of current Types IV, VI, and VIII.
How current is FF-S-86?
Very — it's one of the more actively revised federal fastener specifications, with Revision J issued April 1, 2025, superseding Revision H from June 2021.
Need FF-S-86 Socket-Head Cap Screws?
Ananka Fasteners manufactures current-revision FF-S-86 socket-head cap screws with full material traceability and Mill Test Certification.
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