weldable aluminum fittings

[bobnoffs]

.hi all,
the fuel return in the tank i am building needs an aluminum tube inside the tank to divert the return flow away from the pickup. i can get female npt flanges to weld but how do i handle a female npt on the inside of the tank so i can screw a flare fitting [1/4npt] into the return line and attach a 3/8''o.d. line? maybe a full coupling thru the tank wall would work?
bob noffs

[Frank Giger]

I think you'd be better off welding a bit of billet or a cylinder of solid aluminum to the tank, drilling and tapping it with threads.

[WLIU]

The aerobatic guys deal with this by welding on a NPT flange, then installing a "pickup tube adapter" in that. Aircraft Spruce sells this -> http://www.aircraftspruce.com/catalog/appages/putubeadp.php?clickkey=7861

If you want a right angle, a "flop tube adapter" is on the ACS web site at http://www.aircraftspruce.com/catalog/appages/floptubeadp.php?clickkey=10769

The adapter is threaded on the outside to screw into the tank, and then you screw a smaller fitting into it.

Best of luck,

Wes

[bobnoffs]

i can't quite follow the flop tube fitting. any down side anyone can see to ..........make a 1 3/4'' disc out of 1/8'' 6061 and drill a hole thru it that an aluminum coupling will fit in. weld one side of disc to coupling. slip coupling thru fuel tank wall. weld coupling to fuel tank wall. weld disc to other side of fuel tank wall.now a female fitting inside and out of fuel tank that an an816 nipple will screw into.
bob noffs

[Carbiener]

McMaster Carr sells 6061 aluminum pipe couplings with double female threads. Use them all the time to make fuel tanks.--Ross

[bobnoffs]

good to know ross, thanks. i have already ordered fittings from boyd welding and a full coupling was on the list.
bob