How can I avoid excessive junk on inside junction, when cementing PVC sprinkler pipe?
That level of glop is not normal.

Some things to check:


Is the pipe end deburred?  A file plus sandpaper to finish works well.
Are the pipe &amp; fittings dry?  Water can do strange things to PVC cement.
Be firm, but don't push too hard, and don't over rotate.  1/8 of a rotation is enough.
Work quickly, but do let any residual drips in the primer evaporate before moving on to glue.