Types stocked: Plain (uncoated) · Zinc plated · Hot-dip galvanized
Scope
ASTM F844 covers plain (flat), unhardened steel washers for general-purpose use. It defines dimensions — inside diameter, outside diameter, and thickness — in inch-series sizes from 1/4" through 3" nominal, plus a narrow and wide series.
F844 is dimensional-first; the underlying material is low-carbon steel without heat treatment. It is not a load-carrying hardened washer — for that, specify F436.
Types and finishes
F844 covers washers in:
- Plain (uncoated) — the default
- Zinc electroplated per F1941 — interior and controlled environments
- Hot-dip galvanized per F2329 — exterior and corrosive atmospheric
- Mechanically galvanized per B695 — alternative HDG
- Black oxide / black phosphate — industrial corrosion protection
Stainless flat washers are generally supplied under separate spec references rather than F844 (F844 is a carbon-steel-based standard), though the dimensions are commonly cross-referenced.
Dimensional series
F844 includes three series that share nominal bolt sizes but differ in OD and thickness:
- Narrow series — slightly smaller OD than standard; for bolts installed in tight clearances
- Standard series — the default
- Wide series — larger OD for extra load distribution over soft or thin materials
Typical dimensions (standard series):
| Bolt size | Nominal ID | Nominal OD | Nominal thickness |
|---|---|---|---|
| 1/4" | 9/32" | 5/8" | 0.065" |
| 5/16" | 11/32" | 11/16" | 0.065" |
| 3/8" | 13/32" | 13/16" | 0.065" |
| 1/2" | 9/16" | 1-1/16" | 0.095" |
| 5/8" | 11/16" | 1-5/16" | 0.095" |
| 3/4" | 13/16" | 1-7/16" | 0.134" |
| 7/8" | 15/16" | 1-3/4" | 0.134" |
| 1" | 1-1/16" | 2" | 0.134" |
| 1-1/4" | 1-5/16" | 2-1/2" | 0.165" |
F844 vs F436
The most common spec-selection question:
| Factor | F844 | F436 |
|---|---|---|
| Hardness | Unhardened (soft) | Hardened (38–45 HRC) |
| Application | General load distribution | Structural high-strength bolts |
| Typical bolt pairings | A307, A449, F1554 Gr 36/55 | F3125 A325/A490, F1554 Gr 105, A354 BD |
| Cost | Lower | Higher |
| Acceptable for structural? | No | Yes |
A hardened F436 washer resists embedment into mating steel at the high contact pressures developed by tensioned structural bolts. An F844 washer will dent into the beam flange, the bolt will lose pretension, and the connection will loosen. Specifying F844 where F436 is required is a common field error and a connection integrity issue.
Applications
- General bolted assembly (every imaginable use)
- Load distribution under bolt head or nut on soft materials (aluminum, wood, composite)
- Hole-size compensation (wide series) when bolt hole is oversized
- Machinery and equipment mounting
- Anchor bolt terminations (F1554 Gr 36 and 55)
- Interior and protected-exterior service
Recommended pairing
| Application | Bolt | Washer |
|---|---|---|
| General mechanical | A307 | F844 standard |
| Anchor bolt (light) | F1554 Grade 36 | F844 standard |
| Anchor bolt (weldable, general) | F1554 Grade 55 | F844 standard |
| Anchor bolt (high-strength) | F1554 Grade 105 | F436 (hardened) |
| Structural connection | F3125 | F436 (hardened) |
| Heavy machinery | A449 | F844 typically; F436 if tensioned |
Marking
F844 washers do not carry individual grade markings. The supplier's mill certificate identifies series, dimensions, thickness, finish, and heat traceability.
Related specifications
- F436 — Hardened washers for structural and high-strength service
- F959 — Compressible direct tension indicator washers
- F2329 — Hot-dip galvanizing (when coated)
- F1941 — Zinc electroplating (when coated)
- B18.22.1 — Dimensional standard (type A and type B plain washers; cross-referenced with F844)
Documentation
California Fastener F844 orders ship with mill certificates showing series, dimensions, finish, and heat number traceability.