So, in order to get a picture here, why would one think this would be any different than welding two pieces of flat bar- square or rectangular, angle iron, or plate together? Round bar. So, just makes the welds get shorter with each layer filling up the groove.
Any applicable Clause 3 bevel groove joint should do the trick. Bevel from one side, weld about 3/4 of the way up, backgouge from the other side, weld all the way up, go back and finish the weld from the first side.
Easy WPS to fill out once one knows all the rest of the criteria and is sure that material, welding process, and other variables qualify for a Pre-Approved WPS. If not, then it will need a PQR first.
He Is In Control, Have a Great Day, Brent