MIL-DTL-1222 — Studs, Bolts, Screws & Nuts, High Reliability
MIL-DTL-1222 is the general specification for standard studs, hex cap screws, heavy hex bolts, socket head cap screws, and nuts used in submarine safety and other applications where a high degree of reliability is required. Revision J (8 Dec 2000) superseded MIL-S-1222H, which in turn had replaced the earlier MIL-B-857.
At a Glance
Overview
MIL-DTL-1222 covers standard studs, hex cap screws, and heavy hex bolts in nominal diameters from 1/4" to 4", nuts from 1/4" to 3", and socket head cap screws from 1/4" to 1½", for submarine safety and other applications where a high degree of reliability is required. It's intended for general, high-temperature, high-strength, and corrosive-environment service.
Rather than defining a wholly new part family, the specification is written to qualify commercial off-the-shelf fasteners with added inspection requirements to verify the required reliability — meaning a standard commercial bolt geometry can be procured under MIL-DTL-1222 provided it passes the specification's material, process, and inspection requirements.
- Revision J (December 8, 2000) is the current active issue, superseding MIL-S-1222H.
- MIL-S-1222 itself had earlier replaced the cancelled MIL-B-857.
- Grades are called out numerically (e.g. Grade 500) and referenced alongside commercial standards such as ASTM F593 for CRES fasteners.
Type & Style Configurator
MIL-DTL-1222 defines multiple types for each fastener category, plus thread-class combinations by style.
Style & Thread Class Table (Studs)
| Style | Stud End Thread Class | Nut End Thread Class |
|---|---|---|
| Style A | Class 5 | Class 3A |
| Style B | Class 5 | Class 2A |
| Style C | Class 3A | Class 3A |
| Style D | Class 3A | Class 2A |
MIL-DTL-1222 is the modern, active continuation of the historical MIL-B-857 and MIL-S-1222 lineage. If you're cross-referencing an older shipboard drawing that cites MIL-B-857, MIL-DTL-1222 is the specification to procure against today.
MIL-DTL-1222 — Frequently Asked Questions
What's the difference between MIL-S-1222 and MIL-DTL-1222?
They're the same lineage of specification under different naming conventions — MIL-S-1222 was reissued in the "DTL" (detail specification) numbering format as MIL-DTL-1222. Revision J of MIL-DTL-1222 directly supersedes MIL-S-1222H.
What size range does MIL-DTL-1222 cover?
Studs, hex cap screws, and heavy hex bolts from 1/4" to 4" nominal diameter; nuts from 1/4" to 3"; and socket head cap screws from 1/4" to 1½".
Does MIL-DTL-1222 require custom-designed hardware?
Not necessarily. It's structured to allow procurement of commercial off-the-shelf fastener geometries, with additional inspection and certification requirements layered on to verify the high reliability the specification demands.
Need MIL-DTL-1222 Fasteners to Print?
Ananka Fasteners manufactures MIL-DTL-1222 studs, bolts, screws, and nuts with full material traceability and Mill Test Certification on every lot.
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