Plumbing an Air Tank

[SmashedS10]

Ok I feel stupid asking this, but Im trying to plumb my rear bumper as an air tank 8x4x54 rectangle tubing. I got the tube all sealed off but I took some NPT fitings and drilled some holes and welded around the fitting and test it leaked so I welded more use lots of teflon tape still leaked so welded more and more teflon and still leaked is there a special way to seal off the inlet/outlets of air tanks.

sorry if I sound dumb, but I need some help

[808toy]

There was a recent thread in which one person used teflon tape and some sort of plumber's dope-type of goo. Also, when you are welding this, be careful of warpage of the metal of both the nut/bung and the tube (or bumper in your case). I would start over and if you can get a nut/bung that has more material (thicker) that may help with warpage. What material are your fittings?

[SmashedS10]

Bumper is 3/16 thick they are brass fittings I think thats the problem
Do they make steel fittings?

[808toy]

I would stay with the brass fittings. I use brass fittings and teflon tape with no problem. I don't remember exactly what plumber's goo that was mentioned in the thread I spoke about but, try taking a look at what is available at your local home depot. Some sort of liquid/goop that hardens may do the trick in sealing those leaks. Try that first and if that doesn't work try making another bung with more material. It may be warping when you are welding and this could help with that.

I had a friend use lock-tite and while that did the trick for him, he won't be taking that fitting off anytime soon.

[imhuge999]

I am not sure I understand what part is leaking but you said you drilled some holes and got some brass NPT fitting and when you welded them into your steel bumper they leaked? So you welded more and it [the weld area] still leaked? Seems to me like the brass-to-steel welding is not working out too well (go figure). The "goop" is called pipe dope and is used by plummers and pipe fitters (gas and non-drinking water). It will help seal the threads (kinda like teflon tape) but it will not weld brass to steel.

http://kingssupply.com/usrimage/tefpaste.jpg

I used some Permatex Hydraulic Sealant (p/n 54550 if you're interested) because I had some left over from my hydro steering project and I am happy with the way it worked out. Permatex's Data Sheet (http://www.permatex.com/MSDS_data/tds_industrial/54550.pdf)

[SmashedS10]

Thanks Ill cut that section out redrill it and try out some of that stuff

[808toy]

Whoa, didn't catch that part where you welded brass to steel. Yes, that will not work.

[smitrock]

i tapped and threaded mine, doesn't take a whole lot of thread engagement
it has worked well for several years. used the tape on the threads

[broncdawg]

Sounds like you just drilled and tapped the holes.
You need to weld on threaded steel bungs to the holes so there is enough thread to seal. Then you just make sure your welds are good on the bungs.
Welding supplier or good hardware store will have the bungs.