It is probably electrolytic corrosion due to dissimilar materials in a wet
environment. The solution is to isolate the lifelines from the stanchions if
possible. You might try using passivation paste on the corrosion. This can
be obtained from a welder's supply. Thoroughly wash with water after using
the paste and use rubber gloves. This will remove all iron particles from
the surface. If you are lucky, there will be no pits and mechanical
polishing will not be necessary. Do not get the paste on the lifelines. Try
using heat shrink tubing for isolation.
Steve

"Steve" wrote in message ...
I have Stainless staunchions and life line fittings (all Ronstan I think
although I could be wrong about the make of the staunchions) which are for
some reason getting discoloured by something that looks suspiciously like
rust where the line goes though the staunchions. There is no sign of this
rust colour anywhere apart from on the interface between the two. The
Ronstan pelican hooks are looking decidedly rusty.

Does anyone have any idea why this is happening and more importantly what
if anything I can do to fix it?

Is there a cleaning product suitable for getting it back to looking nice?

Cheers,

Steve