Tube sheet Packing Support Spring

[arhambone]

I am looking for information (proper name, manufacturer)for a spring that will fit inside a heat exchanger tube sheet tube and support packing. I have heard of these in the past but I am having trouble locating a manufacturer of these, probably because I'm not sure what the are called. I believe you use a drill to insert these up into the tube. They compress when being inserted and when you release the spring they expand out and will support the packing above them. Thanks...