Any groove detail, V-, Bevel, J-, U-, ect., with extension tabs should eliminate the incomplete fusion issues at the starts and stops. Check D1.1:2010 Clause 5.31.1 or D1.1:2015, Clause 5.31.1.
Al
UUMM, did I miss something? To be a Pre-Qualified CJP joint with 2" solid round bar, you will need to make sure your material is in the approved base materials list in Clause 3 Tables. Then, you will need to make sure you are using an approved process and electrode in combination with the material.
NOW, you can decide if there is a Pre-Approved joint configuration that will fit your need.
A question, this is not a PJP Flare Bevel or Flare V Groove weld? So the end of the round bar is being welded to??? a plate? another bar? ?? Just wondering.
He Is In Control, Have a Great Day, Brent