PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

6431Washer,lock

Stronghold Screw Products · NSN 5310-00-209-1521 · FSC 5310 · No Item Name Available
Verified by PartsTable
NSN 5310-00-209-1521 — this item is cataloged by the U.S. Government under National Stock Number 5310-00-209-1521. Primary manufacturer part number: 6431.
Features
  • Washer,lock — FSC 5310
  • Hardness Rating: 45.0 ROCKWELL C MINIMUM AND 53.0 ROCKWELL C MAXIMUM
  • Style Designator: SPLIT HELICAL-RIGHT HAND
  • Surface Treatment: CADMIUM OVERALL
  • Material: STEEL OVERALL
  • Hole Diameter: 0.573 INCHES MINIMUM AND 0.595 INCHES MAXIMUM IN
  • Material Document and Classification: FED STD 66,AISI C1060 THRU C1080 OR SAE 1060 THRU 1080 MIL STD SINGLE MATERIAL RESPONSE OVERALL
  • Material Thickness: 0.113 INCHES MINIMUM AND 0.123 INCHES MAXIMUM IN
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Overall construction
General Description

The Washer,lock, cataloged under National Stock Number 5310-00-209-1521, is classified within Federal Supply Class 5310 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is Stronghold Screw Products. Government technical data includes 9 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN5310-00-209-1521
Primary Part Number6431
Item NameWasher,lock
FSC / FSG5310 / 53 — No Item Name Available
ManufacturerStronghold Screw Products
StatusACTIVE
Hardness Rating45.0 ROCKWELL C MINIMUM AND 53.0 ROCKWELL C MAXIMUM
Style DesignatorSPLIT HELICAL-RIGHT HAND
Surface TreatmentCADMIUM OVERALL
MaterialSTEEL OVERALL
Hole Diameter0.573 INCHES MINIMUM AND 0.595 INCHES MAXIMUM IN
Material Document and ClassificationFED STD 66,AISI C1060 THRU C1080 OR SAE 1060 THRU 1080 MIL STD SINGLE MATERIAL RESPONSE OVERALL
Material Thickness0.113 INCHES MINIMUM AND 0.123 INCHES MAXIMUM IN
Outside Diameter0.975 INCHES NOMINAL IN
Surface Treatment Document and ClassificationQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 12
6680-00-085-7589643-1 INTERCHANGEABLE
Indicator,flow
Ametek Inc Schutte and Koerting Div
5950-00-137-4728990-016-91 INTERCHANGEABLE
Transformer,electri
Ametek Programmable Power, Inc.
3110-00-156-5451018-7804 INTERCHANGEABLE
Bearing,ball,annular
Marathon Le Tourneau Co
5970-00-215-38941069981 INTERCHANGEABLE
Insulator,field Con
Chrysler Realty Company Llc Dba Daimler Chrysler
6130-00-235-1000SM-D-96985 INTERCHANGEABLE
Vibrator,interrupter
Us Army Communications & Electronics Materiel Readiness Command Logistics Engineering Dir
5945-00-349-7028643-1 INTERCHANGEABLE
Relay,solid State
Teledyne Defense Electronics, Llc Dba Teledyne Relays Div Https://www.teledyne.com/what-We-Do/
4820-00-446-3237401341ITEM89 INTERCHANGEABLE
Valve,angle
Johnson Controls Navy Systems, Llc
5950-00-583-452210-60030-2 INTERCHANGEABLE
Transformer,power Autotransforme
The Boeing Company Div Defense
4820-00-662-883964-31 INTERCHANGEABLE
Seat,valve
Dresser Industries Inc Leroi Div
5930-00-904-67246431-2-100 INTERCHANGEABLE
Switch,pressure
Horizon Aerospace Llc Dba Transicoil
Cross-Reference Index
Part NumberManufacturer
6431 Stronghold Screw Products (USA)
MS35337-49 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
Related Parts
6680-00-085-7589INTERCHANGEABLE
INDICATOR,FLOW
643-1
5950-00-137-4728INTERCHANGEABLE
TRANSFORMER,ELECTRI
990-016-91
3110-00-156-5451INTERCHANGEABLE
BEARING,BALL,ANNULAR
018-7804
5970-00-215-3894INTERCHANGEABLE
INSULATOR,FIELD CON
1069981
6130-00-235-1000INTERCHANGEABLE
VIBRATOR,INTERRUPTER
SM-D-96985
5945-00-349-7028INTERCHANGEABLE
RELAY,SOLID STATE
643-1
4820-00-446-3237INTERCHANGEABLE
VALVE,ANGLE
401341ITEM89
5950-00-583-4522INTERCHANGEABLE
TRANSFORMER,POWER AUTOTRANSFORME
10-60030-2
4820-00-662-8839INTERCHANGEABLE
SEAT,VALVE
64-31
5930-00-904-6724INTERCHANGEABLE
SWITCH,PRESSURE
6431-2-100
6640-01-051-4944INTERCHANGEABLE
TEST TUBE,BLOOD COLLECTING
6431
5935-01-296-8745INTERCHANGEABLE
CONNECTOR BODY,PLUG,ELECTRICAL
6431

Frequently Asked Questions

What is NSN 5310-00-209-1521?

NSN 5310-00-209-1521 is a Washer,lock, manufactured by Stronghold Screw Products, classified under FSC 5310 (No Item Name Available). Status: active.

What are the part numbers for NSN 5310-00-209-1521?

NSN 5310-00-209-1521 has 2 cross-referenced part numbers: 6431 (Stronghold Screw Products), MS35337-49 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M).

What NSN replaces 5310-00-209-1521?

There are 12 known substitutes for 5310-00-209-1521: 6680-00-085-7589, 5950-00-137-4728, 3110-00-156-5451 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 6431?

Key specifications for 6431: Hardness Rating: 45.0 ROCKWELL C MINIMUM AND 53.0 ROCKWELL C MAXIMUM; Style Designator: SPLIT HELICAL-RIGHT HAND; Surface Treatment: CADMIUM OVERALL; Material: STEEL OVERALL. 9 total characteristics are documented in the Federal Logistics Information System.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com