A metal pipe punctured a hole 2'' x 2'' through my hull and would like advice on repair ? Should I Rivet in a patch or weld ?

If you have insurance, send it to Lund and let them fix it right.

A riveted patch is the answer unless some structural element was damaged, too.

But:
What model and year boat?
Is it still under warranty?
Where exactly is the damamge?

These questions make a difference.

You should check with your local Lund dealer.

If it is a simple boat with very little to remove you could have it done by somebody competent at riveting.
Most Lund dealers can do the job, so can most aircraft maintenance guys

But... if the boat is a relatively new...and a bigger, more expensive model, and still under warranty then maybe it should get approved for local repairs before proceeding.

Like the poster above says...it may be determined it is best to go back to the factory...depending on just where the damage is, what model and how new this boat is.
Like I said... see your local Lund dealer.