"David Lesher" wrote
Some lines actually used spheres between, but they bring their own
problems...

A little further OT,... I've watched a lot of heavy #6 (needs to be heated
to pump) unloaded at the offshore platform. When the tanker is empty, we pig
the pipe and backfill with #2. The methods seem crude to the observer, but
the results are exact enough even for the accountants.