Either a steel nipple or plastic how do you drive the nipple into a hollow smooth pipe.
Threads on both ends . Main purpose is thenipple with threads stick out of the pipe's end perhaps a 1 inch. So a slip nut could be turn on the nipple. Do you just pound the nipple
Down the hollow pipe, or should you pound a threaded bushing down the pipe first?

Your views

You don't pound it. You get a threaded adapter that glues in or on the smooth pipe and then thread the nipple into it. What is this pipe and diameter?

Caliper reads 100 outside dia. Inside 0.18

You didn't tell me the material of the pipe. Is it metal or plastic. "Caliper reads 100 outside dia. Inside 0.18. 100 what? Millimeters? 1.00 inch? Based on your picture, I don't think your measurements are correct. Inside would be close to 100 or 1.00 inches too. 0.18 wall thickness perhaps?

I will just bring the pipe to the store. Like you said threaded adapter,
Other type is insert nut. Both have threads you can screw a nipple
Thanks appreciate it