I don't know about 14.6 but other than the lap joints as you mentioned D1.1 doesn't give maximum sizes. That is usually left to common sense, good judgement, and customer specs if any.
CHGuilford
Looks like maybe you're dealing with tee joints ? If so, I can only say as far as D1.1 goes, as long as it's not a TYK' (tubular) design where fatigue is specified as a design consideration, I see nothing in D1.1 except the single pass applications (ruled by either 3.7.3.2 or tables 4.4 and/or 4.5) that would restrict fillet welds to a maximum size. With extremely acute angled TYK heels, it's not so much a maximum size called out, instead a fillet over a certain size could completely cover over the groove joint's filler metal. That could create a notch effect at the base metal where the fillet's face is reentrant onto the base metal. Good luck, hope it helps you out.