Is there snap mode??

cha

While taking piping lenier diameter length I could not make exact pointer on the pipe segment

Jacob Bradley

Cha,
I believe what you are looking for is a feature named "Snap to Content". This is toggled on and off by selecting "ctrl+Shift+F8" or selecting it from the View tab menu.

Luke Shiras

This is also found in the lower right corner of your window.