Apart from referring UG-37 of Sec.VIII Div.1, there has been numerous discussions of this topic if you search this forum. Richard Ay has suggested another ingenious method for such cases where cylinder to cylinder connection is co-axial/collinear.
I believe such cases can be 'converted' into sphere to cylinder case by equivalent diameter method. In one of the codes there is infact a nice example of such problems. It is unfortunate that I really can't remember it.
PD5500 is also more or less same as EN13445, so even that can be referred.