Here's the regs on fittings, but not whether they need to be approved or not.
Another one of those wonderfully fuzzy areas.
http://www.uscgboating.org/regulatio...rds_partm.aspx
They're clear on hose clamps and swaged fittings (which as previously mentioned cannot be done by hand) and screw type fittings. (Break out the loctite)
Fittings must meet these standards apparently:
http://www.uscgboating.org/assets/pd...L/FUEL-F26.gif