Balls are a common mechanical
component used in nearly all
complex—and many simple—
mechanical products. The critical
nature of balls is illustrated by the
fact that ball bearing factories were one
of the primary targets for Allied bombers
seeking to disrupt the German war
industry during World War II. While
the vast majority of balls are made of
some type of steel, steel’s relatively weak
resistance to chemical attack means
that applications involving aggressive
environments generally require a more
exotic material. This article will examine
the major materials used to enhance balls to resist aggressive environments
and help in selecting the right one.
Brass Balls
Brass balls provide excellent resistance
to corrosion by water, including
seawater, and also resist the corrosive
effects of fuel oil, gasoline, butane,
dry carbon oxide, benzene and similar
chemical agents. However, it should be
noted that brass can be unstable in the
presence of acids and bases.
Another key advantage of brass balls
is their cost, which is substantially lower
than other corrosion-resisting balls.
Brass balls have a Rockwell B hardness
of 75 to 87, which makes them suitable for applications where the balls are only
required to withstand a medium load.
Brass provides excellent electrical conductivity,
so it is well suited for many
electrical applications. A silver coating
is sometimes applied to brass balls
to improve their electrical conductivity
and corrosion resistance to even higher
levels.
Brass balls’ combination of resistance
to corrosion from water and high
hardness make them suitable for water
valves, including high-pressure applications.
Brass valves are even used in fire
nozzles where they must withstand high pressures and flow rates. Brass balls
are frequently used in electrical equipment,
most often in the role of connectors
that make an electrical circuit. For
example, brass balls are used in wireless
power devices, data storage equipment,
heating units and kitchen applications.
Another common application is the use
of brass balls in the pumps of sprayers
used to apply fertilizer and pesticides to
lawns and crops.

Monel Balls
Monel balls provide an even higher
resistance to corrosion than brass
balls. Monel is composed primarily of
nickel and copper, and also has smaller
amounts of other elements such as
iron, silicon, manganese, carbon, aluminum,
titanium and sulfur. Monel
balls are impervious to the effects of
fresh water, salt water, steam, petroleum
products, ammonia, acids, many
bases and calcium chloride. Monel also
has a relatively high tensile strength
of 79 to 90 Kpsi and yield strength of
24 to 40 Kpsi. Monel has a hardness
of 85 to 95 Rockwell B, while its sister
alloy, k-monel can be hardened to
about Rockwell 27 C. K-monel also
offers superior resistance to bases. On
the other hand, monel balls are relatively
expensive because of the difficulty
involved in machining them.

Monel balls are frequently used in pump, valve and metering applications
in water treatment and chemical plants
because they resist attacks by a wide
range of chemicals, and because their
strength enables them to withstand
high flows and pressures. In particular,
monel balls’ ability to withstand ammonia
makes them particularly useful in
wastewater treatment and chemical
plants. Monel balls’ corrosion resistance enables them to provide longer life than
chrome or stainless steel balls in water
supply, wastewater and hydroelectric
applications. They are used in meters
that measure the flow of liquid and
gases because their ability to withstand
most any chemical makes for a more
versatile instrument. Since monel balls
are resistant to both petroleum oils and water, they are ideal for valves in the oil
and gas industry. The added hardness of
k-monel makes them well suited for use
in bearings that must survive aggressive
environments.