BLEED RING

Go here

www.mac-weld.com/FlushRing-Bleed ... dRing.html

If you looked at the link in my previous reply you have seen what a "Bleed Ring" looks like.

Now for the other part of your question. Why do they exist or what are they used for?

Let's say you have a piping system that is lined steel. The lining might be PTFE, Teflon, Glass or some other type of non-weldable material. You might also have an FRP system.

All of these systems require small branch connections such as vents, drains, PI's TI's or "Taps" for Orfice Plates. Making small connections in these systems can be very diffacult and very expensive. So the "Bleed Ring" was created. It is placed between two flanges and the appropreate piping is connected to the tapped outlet.

I hope this is clear and will help you. If not please feel free to ask again.
Jop