MIL-DTL-25027
Self-Locking Nuts
Mumbai · India
Why MIL-N-25027 Became MIL-DTL-25027
The “MIL-DTL” prefix identifies a Detail Specification within the US Department of Defense’s modern specification numbering system — a broad standardization effort that reorganized how military specifications are prefixed and categorized, replacing many of the older single-letter prefixes (like “MIL-N” for nuts, “MIL-S” for screws, “MIL-B” for bolts) with the unified “MIL-DTL” designation for detail specifications defining a specific item’s requirements.
For a buyer, the practical impact is almost entirely about which name shows up on the drawing or purchase order, not about the nut itself changing. A part built correctly to MIL-N-25027 and one built correctly to MIL-DTL-25027 should be functionally identical — same Type I nylon-insert 250°F class, same Type II all-metal 450°F class, same prevailing torque and reuse requirements. What matters for procurement is simply recognizing that both names point to the same family, so a supplier quoting against either reference should be delivering the same qualified part.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and we manufacture and document our self-locking nut range against both the legacy MIL-N-25027 and current MIL-DTL-25027 designations, verified by prevailing torque and reuse-cycle testing under our ISO 9001:2015 quality system.
Where This Designation Genuinely Applies
Matches Current Drawings
Modern engineering drawings increasingly cite MIL-DTL-25027 directly rather than the legacy MIL-N designation.
Same Qualified Requirements
Type I and Type II temperature classes, prevailing torque, and reuse cycle requirements carried forward unchanged.
No Ambiguity for Cross-Reference
Confirms to procurement teams that both designations reference an identical, fully interchangeable part family.
Full Aerospace Traceability
Complete heat and lot documentation with prevailing torque test records regardless of which designation is cited.
Type I and Type II in Detail
MIL-N-25027-1 Nylon Insert Nuts
Nylon insert locking ring rated to 250°F continuous — the most common variant for general airframe and cabin-zone assembly. See our dedicated Type I page for full detail.
View MIL-N-25027-1 → Umbrella ReferenceMIL-N-25027 Legacy Designation Page
Our full umbrella page covering both temperature classes under the original legacy designation, with the same Type I vs Type II comparison detail.
View MIL-N-25027 →Type I vs Type II — Quick Reference
Confirming the actual sustained temperature the assembly will see avoids specifying a locking feature that degrades in service. This table is the quick reference we use with buyers before quoting, whichever designation the drawing cites.
| Aspect | Type I | Type II |
|---|---|---|
| Locking Mechanism | Nylon insert ring | All-metal deformed thread |
| Temperature Rating | 250°F continuous | 450°F continuous |
| Typical Use Zone | General airframe, cabin systems | Engine-adjacent, high-heat zones |
| Designation Used | MIL-DTL-25027-1 / MIL-N-25027-1 | MIL-DTL-25027-2 / MIL-N-25027-2 |
MIL-DTL-25027 Specification Details
Materials We Manufacture In
- Carbon/Alloy Steel Cadmium / Zinc-Nickel Plated
- Stainless Steel 300 Series, Passivated
- Locking Insert Nylon (Type I)
- Finish Per Corrosion Environment
How Self-Locking Nuts Are Made
- Process Cold Formed / Machined
- Locking Feature Insert or Deformed Thread
- Testing Prevailing Torque / Reuse Cycles
- Quality Batch Sampled
Available Dimensions
- Nominal Size #4 – 1″ (Inch Series)
- Metric Equivalent Available to Drawing
- Type Type I (250°F) / Type II (450°F)
- Matching Standard NAS / AN Bolt Series
Application Areas
Wherever aerospace-grade vibration resistance and repeated-reuse reliability genuinely matter.
Aircraft Airframe Assembly
fastening applications
Engine & Nacelle Structure
for higher-temperature zones
Defense & Military Vehicle Assembly
vehicle applications
Rocket & Launch Vehicle Hardware
fastening requirements
Ground Support Equipment
ground equipment assembly
Marine & Naval Aviation Equipment
aviation procurement
High-Vibration Industrial Equipment
vibration-prone assemblies
General Aerospace-Grade Fastening
is explicitly specified
Standard Export Documentation
Prepared as standard practice for every MIL-DTL-25027 self-locking nut shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Prevailing Torque Test Records
Batch-level testing confirming locking torque falls within the specified range for the ordered type.
Certificate of Conformance
Confirms the shipment matches the purchase order type/material specification, citing either designation as required.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
NABL Accredited Test Reports
Independent mechanical and dimensional testing available on request for critical applications.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
MIL-N-25027 Self-Locking Nuts
Our umbrella page under the original legacy designation, covering the same Type I/II family.
View MIL-N-25027 →MIL-N-25027-1 Nylon Insert Nuts
Our dedicated detail page for the Type I nylon-insert variant.
View MIL-N-25027-1 →MIL-I-8846 Helical Coil Inserts
Our companion thread reinforcement specification, often used alongside self-locking nuts.
View MIL-I-8846 →Fasteners Manufacturer & Exporter to the USA
Our broader capability manufacturing to ASTM/ASME and US federal/military standards.
View USA Export Guide →Whichever Designation
Your Drawing Cites
Tell us whether your drawing references MIL-DTL-25027 or MIL-N-25027 — we manufacture and document the same qualified part family either way. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in