Impulse Tapping for Process

You say, "Hi frnds, we use 3 types of Impulse tube tappings".

Well, if you use all three, why ask us?

Tell us how you use them presently and we may have an opinion about your use.

If you just want someone to explain how and when and why to use a certain tapping method, you may be disappointed.

The best thing to do is to speak to a control systems guru already at the <...we...> to go through in greater detail. After all, if <...we...> are using them, then the rest of the <...we...> would know what, where, when and why. That, surely, is the best place to ask.

You left off pipe taps (2-1/2D up/8D down). In my 20+ years of U.S. petrochemical experience, I saw at least a gazillion orifice meters with flange taps, and one with pipe taps. It was in an off-site natural gas metering station. The reference above indicates that corner taps are used quite often in Europe, but I wouldn't know. Keep in mind that putting a 1/2D or 1D tap on a small line (or even fairly sizable) would require a fitting to be installed on the neck of a weld-neck flange, which would be frowned upon.