uhmmm...
6 ways to make each pp x 13 pairs = 78 / 1326 = ~.05882
so, roughly 6% of hands you get a pp, in 20k hands, thats 1200 pps.
flopping a set is roughly 11% (counting quads or a boat it's a little more I think, not counting those it's a little less)
11% of 1200 is 132.
So that's 132 flopped sets... to avoid doing the statistical stuff we'll guesstimate about 200 if you run it out to the river.