ASTM B151

Applies to: Copper-nickel (Cu-Ni) rod and bar in alloys UNS C70600 (90/10 Cu-Ni) and C71500 (70/30 Cu-Ni), and copper-nickel-zinc (nickel silver) alloys; used for valve components, fittings, fasteners, and structural parts in marine seawater piping systems.

Does NOT cover: Cu-Ni pipe and tube (ASTM B466/B467); sheet and plate Cu-Ni (ASTM B122); Cu-Ni fittings (ASTM B366 covers nickel-alloy fittings broadly).

• Chemical composition per UNS designation (C70600: 9–11% Ni; C71500: 29–33% Ni)
• Tensile and yield strength in drawn or annealed temper
• Formability and Brinell hardness limits
• Marking with alloy UNS number and temper
• Sulfur content limit for machinability (free-machining grades)

ASTM B151 Cu-Ni rod and bar (alloys C70600 and C71500) are used for valves, fittings, and structural components in seawater piping systems aboard naval vessels, commercial ships, and offshore platforms. Their biofouling resistance and corrosion performance in flowing seawater — particularly resistance to impingement attack at high velocities — make them preferred over stainless steel in dynamic marine applications.

Engineering note: 90/10 Cu-Ni (C70600) is the workhorse alloy for seawater service, offering a good balance of cost, formability, and corrosion resistance. 70/30 Cu-Ni (C71500) provides improved resistance in high-velocity or high-temperature seawater but at higher cost. For fire main systems, specify alloy UNS number explicitly to avoid substitution with naval brass, which has lower seawater corrosion resistance.