MS21250 12-point tension bolts
12-point external wrenching flanged tension bolts in steel, 180,000 psi minimum tensile, rated to 450°F.
MS21250, machined to the standard.
MS21250 is the military standard 12-point tension bolt: a flanged, external wrenching head on a steel shank heat treated to a minimum tensile strength of 180,000 psi and rated for service to 450°F. The military sheet, last issued as revision L in 1989, has been superseded by NASM21250, and the same part numbers are used under both. It is specified where a joint is loaded in tension and a compact, high-torque head is needed.
- Machined from certified bar to the standard; no hot heading
- AS9100D and ISO 9001:2015 quality system; CAGE 8HH90
- DFARS-compliant material available on request
- No minimum quantity; prototype through production
- Material test reports and certificates of conformance with the order
Send the full part number with the dash number and code letters, the quantity, the required delivery and the documentation your purchase order calls for.
MS21250 at a glance
| Detail | Specification |
|---|---|
| Standard | MS21250, revision L (1989); superseded by NASM21250 |
| Title | Bolt, Tension, Steel, External Wrenching, Flanged, 12-Point, 180 ksi Ftu, 450°F |
| Material | Steel, heat treated |
| Thread | UNJF fine thread. 5/16-24 and 3/8-24 are common sizes |
| Strength | 180,000 psi minimum tensile |
| Head | 12-point, external wrenching, flanged; plain or drilled |
| Temperature | Rated to 450°F |
| Typical use | Tension joints in aerospace structure and engines |
Part numbers covered: MS21250 (now NASM21250). Reference only; the current revision of the standard on your order governs.
Reading the part number.
| Element | Meaning |
|---|---|
| First two digits after the dash | Diameter in sixteenths of an inch: 05 is 5/16 in., 06 is 3/8 in. |
| Last three digits | Grip length code from the table in the standard |
| H after MS21250 | Drilled head |
How Cyclone makes them
Bar stock certified to the material specification is cut, turned and threaded to the standard’s dimensions, with drilled heads or shanks and head markings as the part number requires. Plating and locking elements are applied through partner facilities to the standard.
Lead time
Quoted on each order. Because the parts are machined from bar rather than scheduled through a heading run, lead time is set by machining capacity and material availability. Ask for the current lead time with your RFQ.
Quality
Cyclone’s published certifications include AS9100D, AS9120B, ISO 9001:2015, API Spec Q1, API 20E and API 20F. See quality and certifications.
Documentation
Material test reports and certificates of conformance ship with the order. Additional inspection reports and documentation are quoted to the purchase order.
Questions before you quote
Is MS21250 the same as NASM21250?
NASM21250 replaced the military sheet MS21250. Orders call out either number, and the part numbers are the same.
What does 12-point external wrenching mean?
The head has twelve points and is driven from the outside with a 12-point socket or box wrench. That allows a smaller head and more torque than a hex head of the same diameter.
Does Cyclone stock these?
No. Every part is made to order from certified bar, which is why there is no minimum quantity and why the quote confirms sizes and lead time.
Can you quote a cancelled or superseded number?
Yes. Many MS sheets were reissued as NASM or SAE AS standards with the part numbers unchanged. Send the number on your drawing and the quote names the current document.