Gunmetal — a leaded tin-bronze historically known as Admiralty Gunmetal or Ounce Metal — is prized for its castability, pressure-tightness and seawater corrosion resistance, making it a long-standing choice for marine flanges, valves and pump bodies.
Grades & Standards
Available grades and the manufacturing standards commonly applied to gunmetal flanges.
Standards Explained
Technical Data
Gunmetal (C83600, "85-5-5-5") is a leaded red brass casting alloy, sand or centrifugally cast to ASTM B584.
Chemical Composition (% by weight)
| Grade | UNS No. | Cu | Sn | Pb | Zn | Ni (max) |
|---|---|---|---|---|---|---|
| Gunmetal (85-5-5-5) | C83600 | 84.0 – 86.0 | 4.0 – 6.0 | 4.0 – 6.0 | 4.0 – 6.0 | 1.0 |
Composition & minimum mechanical properties per ASTM B584 (sand cast). Centrifugal & continuous cast forms typically exceed these minimums. Mill test certificates issued per EN 10204 3.1 on request.
Mechanical Properties — C83600, Sand Cast (ASTM B584)
| Property | Minimum (as-cast) |
|---|---|
| Tensile Strength | 207 MPa (30 ksi) |
| Yield Strength | 97 MPa (14 ksi) |
| Elongation | 20% |
| Density | 8.83 g/cm³ |
Typical values; exact temper/casting method confirmed at enquiry stage.
Dimensions
Outside diameter, thickness, hub diameter & bolt circle for threaded cast copper alloy flanges, per ASME B16.24, Class 150. Class 300 available on request.
| NPS | Flange OD (in) | Thickness T (in) | Hub Dia. (in) | Bolt Circle (in) | No. of Bolts | Bolt Dia. (in) |
|---|---|---|---|---|---|---|
| 1/2" | 3-1/2 | 5/16 | 1-3/16 | 2-3/8 | 4 | 1/2 |
| 3/4" | 3-7/8 | 11/32 | 1-1/4 | 2-3/4 | 4 | 1/2 |
| 1" | 4-1/4 | 3/8 | 1-15/16 | 3-1/8 | 4 | 1/2 |
| 1-1/2" | 5 | 7/16 | 2-9/16 | 3-7/8 | 4 | 1/2 |
| 2" | 6 | 1/2 | 3-1/16 | 4-3/4 | 4 | 3/4 |
| 3" | 7-1/2 | 5/8 | 4-1/4 | 6 | 4 | 3/4 |
| 4" | 9 | 11/16 | 5-5/16 | 7-1/2 | 8 | 3/4 |
| 6" | 11 | 13/16 | 7-9/16 | 9-1/2 | 8 | 3/4 |
| 8" | 13-1/2 | 15/16 | 9-11/16 | 11-3/4 | 8 | 3/4 |
Dimensions per ASME B16.24, Class 150 threaded cast copper alloy flanges (bolt circle & bolting dimensions are shared with ASME B16.5 steel flanges for joint compatibility). Class 300 dimensions available on request.
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