Military Stud Bolts — Continuous Thread & Double-End
Stud bolts have no head — a headless, externally threaded rod driven into a tapped hole on one end and torqued with a nut on the other, primarily used in naval high-pressure flanges, engine manifolds, and other applications where two mating parts need to be drawn together without a bolt head protruding on the blind side. Ananka manufactures and exports these to customers across 40+ countries.
Military Stud Bolts We Manufacture
Type I — Full Body
Continuous major diameter shank along the full stud length, providing maximum shear cross-section.
Type II — Reduced Body
Shank diameter reduced below the thread root diameter for weight savings or improved fatigue performance.
Type III — Constant Strength
Shank diameter proportioned so the shank and thread root have matched tensile strength, avoiding a weak point at either section.
Type IV — Continuous Thread
Threaded along the entire stud length, allowing the nut position to be adjusted anywhere along the stud's length.
Overview: How Military Stud Bolts Are Specified
Stud bolts are the fastener of choice wherever a bolt head can't be accommodated — most commonly in high-pressure piping flanges, pump and valve bodies, and engine manifolds, where one end of the stud is torqued into a tapped hole in the base component (the "stud end") and the other end receives a nut to draw the mating flange or cover down. Different regions and industries refer to this same hardware as "double-end studs," "continuous threaded rod," or "flange studs" — Ananka manufactures and exports under all of these designations to customers in Oil & Gas, Power, Nuclear, Marine, Aerospace, and Defense sectors.
MIL-DTL-1222 defines the standard configuration matrix: four stud body types (full, reduced, constant-strength, and continuous thread) and four thread-class "styles" (A through D) that pair different thread classes on the stud end versus the nut end, letting engineers balance installation reliability into the tapped hole against a precise fit for the mating nut.
Selecting the correct type isn't just a matter of preference — it directly affects fatigue life. In high-pressure flange service where the joint sees repeated pressure cycling, a Type III constant-strength stud avoids the stress concentration that a Type I full-body stud would see at the thread root, which is why constant-strength studs are frequently specified for critical piping and pressure-vessel connections despite their more complex machining.
- Stud material and finish follow the same high-reliability qualification path as MIL-DTL-1222 bolts and nuts, since studs are covered under the same general specification.
- Double-end studs are torqued in with a stud driver or two jam nuts, since there's no bolt head to grip directly.
- For the matching nuts and washers used with these studs, see Ananka's military nuts, military bolts, and military washers categories.
Which Stud Bolt Type Do You Need?
Body type and thread style are chosen based on load path and mating fit requirements.
Applicable Standards
Explore the individual military stud bolt specifications Ananka manufactures to.
Compliance & Sourcing References
Verify the governing MIL specification through official government sources.
Free specification text for MIL-DTL-1222 and its legacy predecessor MIL-B-857 is available through the Defense Logistics Agency's ASSIST QuickSearch portal. NSN cross-references and procurement history can be checked via DLA DIBBS. Ananka Fasteners manufactures stud bolts to the current active revision of MIL-DTL-1222 and supplies full Mill Test Certification with every shipment worldwide.
Military Stud Bolts — Frequently Asked Questions
What's the difference between a stud bolt and a regular bolt?
A stud bolt has no head — it's threaded into a tapped hole in one component and draws a second component together using a nut on the opposite end, whereas a standard bolt has an integral head that bears directly against the top part.
How is a double-end stud installed without a bolt head to grip?
Typically with a dedicated stud driving tool, or by running two jam nuts together onto the stud end and using the outer nut to torque the stud in — a common shop technique often called "double-nutting."
What does "constant strength" body mean?
Type III studs under MIL-DTL-1222 have their shank diameter proportioned so the plain shank section and the reduced thread-root section have matched tensile strength — avoiding a weak point that could fail preferentially under load.
Does Ananka Fasteners export military stud bolts internationally?
Yes — Ananka manufactures and exports MIL-DTL-1222 stud bolts to customers across 40+ countries in the Oil & Gas, Power, Nuclear, Marine, Aerospace, and Defense sectors, with subsidiary support entities in the UK and USA.
Need Military Stud Bolts to Print?
Ananka Fasteners manufactures MIL-DTL-1222 stud bolts with full material traceability and Mill Test Certification on every lot.
Prefer email? sales@anankafasteners.com
