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ST3M552-4 — WASHER,CONCAVE

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

ST3M552-4: WASHER,CONCAVE.

The WASHER,CONCAVE is a the manufacturer industrial component. Key specifications include radius: 0.260 INCHES NOMINAL IN, material: STEEL COMP 630 OR STEEL COMP 631 OR STEEL COMP 632 OVERALL, hole_diameter: 0.370 INCHES NOMINAL IN, outside_diameter: 0.495 INCHES MINIMUM AND 0.505 INCHES MAXIMUM IN, style_designator: CONCAVE, surface_treatment: CADMIUM AND CHROMATE OVERALL. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-377-0604, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
ST3M552-4
NSN: 5310-00-377-0604
FSC: 5310 — Nuts and Washers
CAGE: 76301 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
radius0.260 INCHES NOMINAL IN
materialSTEEL COMP 630 OR STEEL COMP 631 OR STEEL COMP 632 OVERALL
hole_diameter0.370 INCHES NOMINAL IN
outside_diameter0.495 INCHES MINIMUM AND 0.505 INCHES MAXIMUM IN
style_designatorCONCAVE
surface_treatmentCADMIUM AND CHROMATE OVERALL
material_thickness0.160 INCHES MINIMUM AND 0.170 INCHES MAXIMUM IN
specification/standard_data76301-ST3-552 MANUFACTURERS STANDARD
material_document_and_classificationAMS 5643 ASSN STD 1ST MATERIAL RESPONSE OR AMS 5528 ASSN STD 2ND MATERIAL RESPONSE OR AMS 5520 ASSN STD 3RD MATERIAL RESPONSE OVERALL
surface_treatment_document_and_classificationQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
NSN5310-00-377-0604
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: ST3M552-4 · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
RADIUS: 0.260 INCHES NOMINAL IN
•
STYLE DESIGNATOR: CONCAVE
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 5643 ASSN STD 1ST MATERIAL RESPONSE OR AMS 5528 ASSN STD 2ND MATERIAL RESPONSE OR AMS 5520 ASSN STD 3RD MATERIAL RESPONSE OVERALL
•
OUTSIDE DIAMETER: 0.495 INCHES MINIMUM AND 0.505 INCHES MAXIMUM IN
•
MATERIAL THICKNESS: 0.160 INCHES MINIMUM AND 0.170 INCHES MAXIMUM IN
•
SPECIFICATION/STANDARD DATA: 76301-ST3-552 MANUFACTURERS STANDARD
•
SURFACE TREATMENT: CADMIUM AND CHROMATE OVERALL
TECHNICAL CHARACTERISTICS
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
RADIUS0.260 INCHES NOMINAL IN
STYLE DESIGNATORCONCAVE
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5643 ASSN STD 1ST MATERIAL RESPONSE OR AMS 5528 ASSN STD 2ND MATERIAL RESPONSE OR AMS 5520 ASSN STD 3RD MATERIAL RESPONSE OVERALL
OUTSIDE DIAMETER0.495 INCHES MINIMUM AND 0.505 INCHES MAXIMUM IN
MATERIAL THICKNESS0.160 INCHES MINIMUM AND 0.170 INCHES MAXIMUM IN
SPECIFICATION/STANDARD DATA76301-ST3-552 MANUFACTURERS STANDARD
SURFACE TREATMENTCADMIUM AND CHROMATE OVERALL
MATERIALSTEEL COMP 630 OR STEEL COMP 631 OR STEEL COMP 632 OVERALL
HOLE DIAMETER0.370 INCHES NOMINAL IN
OTHER ITEMS IN FSC 5310 — Nuts and Washers
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5310-00-000-0040 5310-00-000-0077 5310-00-000-0079 5310-00-000-1146 5310-00-000-3815 5310-00-000-4532 5310-00-000-4540
SUBSTITUTES & CROSS-REFERENCES 1
HL382-8PBWReference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is ST3M552-4?
ST3M552-4 is a WASHER,CONCAVE.
What parts can replace ST3M552-4?
There is 1 known substitute for ST3M552-4: HL382-8PBW. Substitute compatibility should be verified for your specific system.
What is the NSN for ST3M552-4?
ST3M552-4 is cataloged in the U.S. Government catalog under NSN 5310-00-377-0604. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.