. The API codes are not distibuted free of charge. If you find a place to obtain them for free, then it is akin to stealing from API, and can probably expect to hear from their attorneys if you download a "free" copy.
I know this is very late to respond to this thread, but if you are still interested in plate tolerances I offer the following. A shell plate is typically layed out and cut to plus or minus 1/16 inch on length and width. The diagonal tolerance is normally i/1 inch. Hope this helps.