The Nut,self-Locking,extended Washer, cataloged under National Stock Number 5310-01-137-5736, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Howmet Global Fastening Systems Inc. Government technical data includes 11 specifications, cited from the U.S. Government catalog. The record lists 7 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-137-5736 |
| Primary Part Number | H52021-4 |
| Item Name | Nut,self-Locking,extended Washer |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Washer Outside Diameter | 0.515 INCHES MINIMUM AND 0.540 INCHES MAXIMUM IN |
| Width Across Flats | 0.305 INCHES MINIMUM AND 0.313 INCHES MAXIMUM IN |
| Thread Series | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Washer Thickness | 0.015 INCHES MINIMUM AND 0.057 INCHES MAXIMUM IN |
| Material Document and Classification | AMS 5709 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Thread Direction | RIGHT-HAND |
| Nominal Thread Size | 0.250 INCHES IN |
| Nut Style | DOUBLE HEXAGON |
| Thread Class | 3B |
| Thread Quantity Per Inch | 28 |
| Material | STEEL OVERALL |
| 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 |
|---|---|
| H52021-4 PRIMARY | Howmet Global Fastening Systems Inc (USA) |
| 2528B331 PRIMARY | Bollhoff Inc. Dba Bollhoff Rivnut Inc (USA) |
| WSLH10-4 PRIMARY | Sps Technologies, Llc Dba PB Fasteners (USA) |
| 4076T14P01 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| GN512B4-331 | Northrop Grumman Systems Corporation (USA) |
| 4076T14P01 | National Aerospace Fasteners Corporation |
| 4076T14P01 | Howmet Global Fastening Systems Inc (USA) |
| Reference | Meaning |
|---|---|
| VN771W048 | 3/2 Design control — primary reference U.S. Government activity |
| 2528B331 | 5/9 Secondary reference Bollhoff Rivnut., Inc. Fastening and Assembly Technology Dba Bollhoff Rivnut., Inc. Div Bollhoff Rivnut., Inc. |
| M52021-4 | 5/9 Secondary reference Howmet Global Fastening Systems Inc |
| 4076T14P01 | 1/2 Source control — Government-approved source U.S. Government activity |
| 4076T1P01 | 5/2 Secondary reference U.S. Government activity |
NSN 5310-01-137-5736 is a Nut,self-Locking,extended Washer, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-137-5736 has 7 manufacturer part numbers on file: H52021-4 (Howmet Global Fastening Systems Inc), 2528B331 (Bollhoff Inc. Dba Bollhoff Rivnut Inc), WSLH10-4 (Sps Technologies, Llc Dba PB Fasteners), 4076T14P01 (Sps Technologies, Llc Dba PB Fasteners), GN512B4-331 (Northrop Grumman Systems Corporation) and 2 more.
Key specifications for H52021-4: Overall Height: 0.307 INCHES MINIMUM AND 0.322 INCHES MAXIMUM IN; Washer Outside Diameter: 0.515 INCHES MINIMUM AND 0.540 INCHES MAXIMUM IN; Width Across Flats: 0.305 INCHES MINIMUM AND 0.313 INCHES MAXIMUM IN; Thread Series: UNIFIED NATIONAL JOINT FINE (UNJF). 11 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.