The Washer,flat, cataloged under National Stock Number 5310-00-003-3869, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Tens Machine Company, Inc. Dba Tens Machine Co Inc. Government technical data includes 13 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-00-003-3869 |
| Primary Part Number | A51B21644-17 |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Tens Machine Company, Inc. Dba Tens Machine Co Inc |
| Status | ACTIVE |
| Surface Treatment Document and Classification | MIL-C-8837 TYPE 2 CLASS 1 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Overall Diameter | 1.500 INCHES NOMINAL IN |
| Heat Treatment | QUENCHED AND TEMPERED |
| Hardness Rating | 46.0 ROCKWELL C MINIMUM AND 49.0 ROCKWELL C MAXIMUM |
| Material Document and Classification | MIL-S-8949 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Cross-Sectional Shape Style | RECTANGULAR |
| Surface Treatment | CADMIUM OVERALL |
| Peripheral Shape Style | ROUND |
| Test Data Document | 81349-MIL-I-6868 SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.). |
| Material | STEEL OVERALL |
| Center Hole Shape Style | ROUND |
| Hole Diameter | 0.441 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN |
| Thickness | 0.188 INCHES NOMINAL IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| A51B21644-17 | Tens Machine Company, Inc. Dba Tens Machine Co Inc (USA) |
| A51B21644-17 | Howe Machine & Tool Corp. Dba Howe Machine & Tool Corp (USA) |
| Reference | Meaning |
|---|---|
| A51B21644-17 | C/1 Advisory reference — outside the item-of-supply concept Northrop Grumman Systems Corporation |
| A51B21644-17 | 3/9 Design control — primary reference Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp Div Northrop Grumman Aeronautics Systems |
| A51B21644-17 | 5/9 Secondary reference Northrop Grumman Systems Corporation |
NSN 5310-00-003-3869 is a Washer,flat, manufactured by Tens Machine Company, Inc. Dba Tens Machine Co Inc, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-00-003-3869 has 2 manufacturer part numbers on file: A51B21644-17 (Tens Machine Company, Inc. Dba Tens Machine Co Inc), A51B21644-17 (Howe Machine & Tool Corp. Dba Howe Machine & Tool Corp).
Key specifications for A51B21644-17: Surface Treatment Document and Classification: MIL-C-8837 TYPE 2 CLASS 1 MIL SPEC SINGLE TREATMENT RESPONSE OVERALL; Overall Diameter: 1.500 INCHES NOMINAL IN; Heat Treatment: QUENCHED AND TEMPERED; Hardness Rating: 46.0 ROCKWELL C MINIMUM AND 49.0 ROCKWELL C MAXIMUM. 13 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.