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MS21083 : Mil-Spec Hardware

MS21083 : Mil-Spec Hardware Specification
Nut, Self-Locking, Hexagon Non-Metallic Insert, Low Heat, 250°F

MS21083 CAD DrawingClick on drawing for larger view



  • Steel Grades
  • 1006 (UNS G10060) per ASTM A29 ASTM A510 or ASTM A853
  • 1008 (UNS G10080) per ASTM A29 ASTM A510 or ASTM A853
  • 1009 (UNS G10090) per SAE J118
  • 1010 (UNS G10100) per AMS 5040, ASTM A29 ASTM A510 or ASTM A853
  • 1018 (UNS G10180) per AMS 5069 ASTM A29 ASTM A510 or ASTM A853
  • 1035 (UNS G10350) per AMS 5080 ASTM A29, ASTM A510 or ASTM A853
  • 1137 (UNS G11370) per AMS 5024 or ASTM A29
  • 11L37 (UNS G11374) per AMS 5020 or ASTM A29
  • 1213 (UNS G12130) per SAE J403 or ASTM A29
  • 12L14 (UNS G12144) per SAE J403 or ASTM A108
  • 1215 (UNS G12150) per ANS 5010

302 (UNS S30200) per AMS 5688, AMS 5636 AMS 5637 or DQ-S-763 303 (UNS 530300) per AMS 5640 ASTM A581, or ASTM MA582, 304 (UNS S30400) per AMS 5447 AMS 5639 or QQ-S-763 (UNS S30452) per ASTM A276 or QQ-S-763, 304L (UNS S30430) per ASTM A493, AMS 5647 or QQ-S-763

Aluminum Alloy

  • 2014-T6 (UNS A92014) per QQ-A-200/2, QQ-A-225/4, or AMS 4121
  • 2017-T4 (UNS A92017) per QQ-A-225/5 or AMS 4118
  • 2024-T6 or T4 (UNS A92024) per QQ-A-225/6 or AMS 4120
  • 7075-T6 or T651 (UNS A97075) per QQ-A-200/11, QQ-A-225/9 or AMS 4123

CA 360 (UNS C36000), ½ hard or CA 260 (UNS C26000) per ASTMM B36, ASTM B121, ASTM A829, or AMS 4610

Non-Metallic Insert – Nylon per ASTM D4088, Group 1, Class 1 or 2


  • Steel and Copper Base Alloy Nuts – cadmium plated in accordance with QQ-P-416, Type II, Class 2
  • Corrosion-Resistant Steel Nuts – Passivate in accordance with QQ-P-35
  • Aluminum Alloy Nuts – Anodize or chemically surface treat in accordance with procurement specification
  • Aluminum Alloy Nuts – In sizes thru 086-56 thru 190-32 dyed blue per procurement specification

3. LUBRICANT: Lubricant approved in accordance with MIL-N-25027 lubricants shall be soluble in the cleaner specified in the procurement specification

4. MAGNETIC PERMEABILITY: Magnetic permeability of corrosion-resistant steel nuts shall be less than 2.0 for a field strength H = 200 oersteds when tested in accordance with ASTM A342 Method 6

5. VIBRATION LIFE: Minimum vibration life requirement shall be three times the average vibration life listed in MIL-N-2507

6. SURFACE TEXTURE: Ro 125 Max in accordance with ANSI/ASME B46 1

7. PART NUMBERS. The part number shall consist of the basic MS number followed by a dash number from Table I.

  • Examples of Part Numbers:
  • MS21083H4 = 250-28 steel nut, non-metallic insert, cadmium plated
  • MS2108384 = 250-28 copper base alloy nut, non-metallic insert, cadmium plated
  • MS21083C4 = 250-28 corrosion steel nut non-metallic insert, passivated
  • MS21083D4 = 250-28 aluminum alloy nut, non-metallic insert, anodized or chemical conversion coating


  • 1. Break all sharp edges and remove all burrs and slivers
  • 2. Dimensions are in inches
  • 3. Design and Usage Limitations. These nuts are intended for shear applications. The steel nuts are designed to develop an ultimate limitations tensile stress (Ftu) of 70 KSI the aluminum nuts are designed to develop an ultimate tensile stress (Ftu) of 70 KSI for sizes -04 thru -3 and 35 KSI for sizes -4 and larger. The CRES nuts are designed to develop an ultimate tensile stress (Ftu) of 70 KSI for sizes -04 thru -8 and 58 KSI for sizes -9 and larger, and the copper base alloy nuts have no axial strength requirements. These ultimate tensile stress requirements are based upon the cross sectional area at the minimum minor diameter of MIL-S-8879 external threads, and will be obtained when the nuts are tested on bolts having a minimum ultimate tensile strength of 160,000 PSI. These nuts are designed to be used on 3A external threads. These nuts shall be used in accordance with the limitations of MS33588.
  • 4. In the event of a conflict between the text of this standard and the references cited herein the text of this standard shall take precedence.
  • 5. Referenced government (or non-government) documents of the issue listed in that issue of the Department of Defense index of specifications and standards (DODISS) specified in the solicitation form a part of this standard to the extent specified herein
  • 6. Bids shall be solicited only from the manufacturers or distributors listed on OPL-25027.
  • Interchangeability Relationship. MS21083 nuts can universally replace AN384, MS20384, and MAS1022 nuts of like material, plating, thread size, and locking design (all-metal or with non-metallic insert). But these AN384, MS20384, and NAS1022 nuts cannot universally replace the MS21083 nuts.

Need the Spec?

Click here to download MS21083 Specification
(PDF Format).

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Twinsburg, Ohio 44087

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GLFTechnical Fastener Supply specializes in a wide range of industrial and military specification (MIL Spec) fasteners; including MS fasteners, AN Fasteners, and NAS Fasteners.