Here are some guidlines I'm familiar with:
Jacketing over insulation, for cylindrical surfaces 30 inches diameter and smaller, shall be secured with 1/2-inch by 0.020-inch bands and seals placed at 12-inch centers, maximum, over each circumferential overlap and at least at the center of each course of jacketing.
Jacketing for cylindrical surfaces greater than 30 inches diameter shall be secured with 3/4- inch by 0.020-inch bands and seals placed on 12-inch centers. As a minimum, bands and seals shall be placed over each circumferential overlap and at least at the center of each course of jacketing. In addition to the bands, longitudinal joints in jacketing shall be secured with sheet metal screws or pop rivets placed on 6-inch centers as required to avoid gaps in the jacketing.
Jacketing shall be applied with 2-inch circumferential or longitudinal laps as applicable.
Sheet metal screws or pop rivets shall not bind adjacent courses of jacketing together at the circumferential lap.
All overlaps in metal jacketing which are not installed in a watershed fashion, such as longitudinal seams in vertical piping and circumferential seams in horizontal piping, shall be sealed with caulking compound.