Pressure testing

[ezrider]

Scott, Rex, or any one else you can help me out here.More and more, lately i am being asked if i can pressure test a tank before being painted. Normally i dont get involved in this part of preporation, but i think its time i start to. Can any one tell me the best way to pressure test a gas tank.Any help will be grately appreciasted.
Thanks in advance.

 

[Motornoggin]

I have only done this once, so my technique may not be the standard, but... I recently removed the unsightly pinch weld from a Vulcan gas tank and re-welded it to get a smooth edge. Before I started to apply the filler I decided to pressure test for leaks. I used a few layers of duct tape over the larger openings and carb vacuum plugs on all but one of the nipples. I used my rubber tipped air nozzle on the remaining open nipple and set my regulator to 15psi and pressurized the tank. I used a strong mixture of dish soap/water in a squirt bottle and went around anywhere where I welded and looked for foam/bubbles. I only had four small pin holes to weld up and I repeated the pressure procces several until I was satisfied it was leak proof. Seemd to work well (I HOPE!!!).
Anyway, just wondering if anyone noticed I used the word 'nipple' twice!

 

[TAZ]

EZ,
Here is how I do it. Don't know if it is the "correct" way of doing it, but it works for me.
I have a large tub set up full of water. I plug all the holes and holes up except one small one on the bottom of the tank. I attach a small vaccum line to this hole (usually where the gas hose goes to the other tank side).

I put my adjustably air blower inside the other end of the hose. Now I slowly open the blower so it is letting air in the tank (not much at all though). Then I lower the tank in the water looking for any bubbles coming from any of the seams. Be sure and check them out thoroughly. Then I pull the tank back out and immediately dry it (especially bare metal tanks.)

If you keep the air going through it before you dunk it in the water, no water gets inside the tank.

 

[rex]

Sorry Joe but I've always let someone else do it when they seal it or let the welder do it.I love to weld but I hate screwing with tanks.I like the ideas here,I used to dump a little gas in the tank and prop it up so it sat in that area for a while.Got lucky the few times too thankfully.I've seen a radiator pressure test pump rigged for it,but you need a set of non vented filler caps.The soapy water or dunk tank tells all then.

 

[ezrider]

Rex, same story here , i have always let the customer take care of it. i have heard of the vaccum pump method also , may be some day i ll get around to fabricating a set up for one. Thanks any way

 

[rex]

I think you had a typo there but just to be sure I meant the little pump with the guage on it to pressurise radiators through a cap adapter.Actually since it had a guage on it,as long as your caps are clamped down good if the needle moves there's a leak.Then you can do the water deal to narrow it down.Damn things are expensive though if you're not gonna take on the work.I never thought of a vacuum guage though,if it'll hold 10 or 15" I'd say she's pretty good.

 

[ezrider]

Scott and Noggin, thanks thats kind of what i had in mind.

 

[ezrider]

Right i have one i use to bleed brakes with a bunch of attachments i am sure i can McGiver some thing up.