If it's part of a ball valve it would be impossible to photograph without showing the ports and pivot axle hole.
Unless . . . it was removed from the manufacturing process prior to drilling the ports . . . and the ports are probably done prior to final machining
Fwiw, ball valves - on and off valves for liquids or gas (in vapor form) can be quite large.
I visited one of California's Aqueduct system pumping plants and the ball valves there were from 6 - 10' in diameter.
They may have been larger, but they were a couple of stories up off the basement floor and judging the size was difficult.
4 1/2" in diameter doesn't strike me as being overly large for a ball out of a large ball bearing.
This site lists ball sizes to 6".
I would not be surprised to find them in sizes up to 12-24", but most times bearings in very large sizes are a babbit type bearing.
Babbit type bearings are a lead/tin alloy that's poured in a receptacle and hand scraped to a final finish size for the shaft.
You'll find these in locomotives, large generators, pumps, motors and similar.
A roller bearing has more load bearing capacity than a ball bearing and could be somewhat smaller in roller diameter for the same axle/shaft size, but
the babbit bearing beats the ball and roller bearings in pure weight carrying capacity.
Babbit bearings have been around a long time and once you get to a certain size - whatever that is - they are more economical to manufacture and use
than a ball/roller bearing.
They can handle dirtier lubricating oil as well due to their embedability properties.
A piece of grit will sink into the soft surface of the babbit - and will scratch or gouge the shaft - but it's able to remain in service with no
Not true with roller and ball bearings.
Once grit gets in them, the roller or ball will stop rolling - much like a chock under a wheel - and in most cases the bearing self-destructs not long
There are stainless ball - and roller - bearing alloys that are very rust resistant.
More than likely this is simply a ball out of a large roller bearing.
I note the comment about the ball being non-magnetic, but a magnet will stick to it.
That statement is a bit at odds with itself, but there are stainless alloys that are mildly magnetic and that's probably what's going on here.
Magnets will not stick to stainless steel sheet metal unless the alloy is a cheaper grade which means less chromium and nickel in the alloy.
Try a magnet on most kitchen stainless sinks and you'll probably find it mildly magnetic.
Try the same with a piece of higher quality stainless and the magnet will not stick.
The magnet test will easily differentiate between common bolts and stainless because stainless bolts have a higher quantity of chromium and nickel in
Here's some info on the metallurgy of stainless steel: en.wikipedia.org...
[edit on 10-11-2005 by Desert Dawg]