Navy M Leaded Bronze UNS C92200 is a copper-tin-zinc-lead casting alloy with a nominal composition of 88% Cu, 6% Sn, 4.5% Zn, and 1.5% Pb, conforming to CDA number 92200. The tin content provides good strength and corrosion resistance in steam and water environments, while the lead addition improves machinability and pressure tightness by filling micro-shrinkage voids. Zinc reduces cost and improves castability compared to unleaded tin bronzes. C92200 is a widely used specification for steam pressure applications involving temperatures up to 550F including steam valves, pump bodies, fittings, and general engineering castings requiring reliable pressure containment. The lead content provides the free-machining characteristics needed for production machining of complex valve and fitting geometries. Supplied in 20 lb ingots for production foundry casting of valves, fittings, and pressure components.
Common technical inquiries regarding Navy G Bronze Alloy UNS C92200
C92200 (Navy M) contains lead (1.5%) and slightly less tin (6% vs 8%) than C90300 (Navy G), making it more machinable and pressure-tight but with marginally lower strength and corrosion resistance. Navy M is the correct choice when machining economy is important and the service environment does not require lead-free construction. Navy G should be specified for marine seawater service, lead-free requirements, or applications demanding maximum corrosion resistance.
C92200 is rated for steam service up to 550F governed by the softening of the tin-zinc intermetallic phases and reduced creep resistance above this temperature. ASTM B61 and B62 both specify 550F as the pressure service limit for these steam bronze compositions and ASME boiler and pressure vessel codes recognize this limit. For steam service above 550F carbon steel, stainless steel, or nickel-aluminum bronze must be substituted.
C92200's 1.5% lead content disqualifies it from potable water contact applications under the US Safe Drinking Water Act amendments which restrict lead to 0.25% weighted average in wetted surfaces of plumbing fixtures. For new potable water system designs lead-free silicon brass (C87500) or other compliant alloys must be substituted. C92200 remains appropriate for steam, industrial water, and HVAC applications where potable water contact restrictions do not apply.
