Have perused now the code and seems not to say anything about. However we must infer a minimum of 1.25D for standard clearance holes just to be able to drive the nut or bolt, and likely more will be even better. You have ample distance to go from the web or flange or box or pipe face, at least to 14 times the lesser plate thicknness, distance to which we may assume it is adequately stiffened from (and more, since the values are for non stiffened plates).
See section 6.2 Connections using bolts.