Cross & Morse has supplied replacement chains to a customer in the
nuclear processing sector that meet a very tough specification at 40%
less cost compared with previously used products. The customer requested
pairs of duplex 5/8in BS roller chain for a lifting application, each to
be 100ft long and lengths of chains in each pair to be matched to within
0.005in. As they had to operate in areas subject to high levels of
radioactivity where normal maintenance is out of the question, they had
to be extremely reliable. Moreover, ordinary greases and lubricants could
not be used, as they break down when exposed to radiation.
The company developed a modified version of its standard 5/8in pitch
duplex chain, managing to achieve length-matching to within 0.001in, and
thus exceeding the design brief by a factor of five. A surface coating is
added to the chain to protect it against corrosion, and a high-viscosity
lubricant is applied under pressure, ensuring full penetration of the
mating surfaces of every link.