I don't believe that I've ever seen black steel thread protectors, and I sure hope I didn't!
IPS - iron pipe size - is one standard of sizing pipes, and is common for schedule 40 PVC. The size refers the inside diameter.
CTS - copper tubing size - is another standard, and is also used for CPVC and some small diameter polyethylene pipe which have thin walls. Of course, CTS copper still has IPS threads.
SDR - standard dimensional ratio - is used for piping, but I've never seen it used to refer to threads. Perhaps if we used SI instead of "English" measurements we could have one system?
[This message has been edited by Dspark (edited 05-22-2001).]
