Since Geroge brought this to my attention, I went and check my inventory of Airpower Tee fittings checking for the markings he describes. I did find a bag that had fittings with these markings. It took a magnifying glass for me to see them but indeed, there are some small scores in the brass nipple. What I found strange... I have literally sold thousands of these Tee fittings, they are one of our most popular items, and never had one complaint of leaks caused by the fittings. I decided to see if I could get one to leak. Took the worst one I could find in the bag of 10, seen in pictures one and two (had to set the camera to Macro for these shots, scores look pretty big here). I tied two of the ports together with some Dreamworks airline, hooked the third to my hand pump and pumped it up to 160psi.... That was an hour ago, still sitting at 160psi. I have wiggled, pulled, flexed the lines in every direction....no leaks.
What I have found is the brand of Airline used makes a huge difference! I was able to get the cheap Asian translucent type airlines to leak on this fitting by bending the line close to the barb BUT.... I plugged that same airline onto another brand metal Tee we carry and I was able to get leaks on that one using the same method as well. Dreamworks airline is made to spec from a heat resistant material with thicker walls and slighly smaller ID for tight, leak free connections.
I would be willing to bet George is using a low quality Asian (usually translucent) airline which is more likely the cause of his airleaks. We stopped using this type of line several years ago for this very reason...

George...I would be happy to replace your Airpower Tee fittings with Tamjet metal Tees if you wish although I doubt this will resolve your leaks. Let me know what you would like to do...
Todd