A question on pressure testing welds?

[Bill Edwards]

No, you use dye on any surface you can get to to reveal defects such as cracks. I'd never thought of it for checking for holes, but it's a thought - I'm sure it would work.

Maker, you spray a penetrant on the surface and it seeps into any cracks that are too small to see. You then wipe it off and apply a developer which draws out any dye that is hidden in a crack and shows that you have a flaw.

 

[Rig Pig]

Yes, diesel is very good at finding leaks as it penetrates, water doesn't.
But water dries off and won't set on fire or contaminate the weld if you find a hole to fill.

Exactly my point, I was less than pleased to have to take the tank off and clean it out and re weld the cold lap.

 

[Bill Edwards]

What's that?

 

[sardine]

If you use water in a steel tank you've got to dry it before it rusts. Which might be a pain on a big tank, or one with only a small filler.

 

[mike os]

I got the impression this was to test/improve his welds, not actually build something... hose pressure will find most faults, if we are talking about a piece that needs to ne 100% sealed then you still have to use a liquid...and not a fuel oil or alcohol .... so you will always have some residue or minor rusting to deal with afterwards. even using I dye I would want some form of pressure test even if just static

 

[Wedg1e]

Fuel tanks are tested at 3.5 psi for inland waterways boats. That's enough to find any leaks.

Funnily enough, when I leak-tested the fuel tank from my TVR that I'd welded, I used about 4psi air as much more than that started to bow the ends of the tank outwards. Then I stuck a length of ruber tubing in my ear and went along the welds listening for hissing noises (as well as having a pressure gauge on the inlet).
The tank's back on the car and holding fuel so it can't have been a bad idea

 

[AdrianH]

OK so I have made the cube. Still having some issues with my TIG welding, sometimes I do not move fast enough and end up with flat welds so have to go over it again with second bead. The nozzle is a turned down M12 bolt.

Hope I got the media right.

Adrian

 

[AdrianH]

Appologise for the shacky vids trying to use the mobile phone in one hand and do stuff with the other, but heres my attempt at pressure testing:-

Time to empty it out and cook a little while on the gas ring to dry out.

Adrian

 

[wookie]

A hosepipe will show any leaks. You could use a pressure washer and it would be safe, provided there is no air in it, all that would happen is a little pinprick hole would open up and squirt water out and all your pressure would go instantly.

Have a look on Colin Furze site, http://www.colinfurze.com/hydroforming.html that shows him using a pressure washer to hydroform steel, and when his welds fail it shows a little leak of water and then the seam splits and all the pressure goes instantly, all very safe as long as you don't have any air in there that can get compressed.

 

[Maker]

Have a look on Colin Furze site, http://www.colinfurze.com/hydroforming.html that shows him using a pressure washer to hydroform steel, and when his welds fail it shows a little leak of water and then the seam splits and all the pressure goes instantly, all very safe as long as you don't have any air in there that can get compressed.

That's where I got most of this info from.

 

[dannyp]

if your welds are good you should be abel to turn a cube into a knobly ball with a pressurewasher. dosent really do anything intresting when it dose fail.

as for testing tanks, i've had diesel weep out of a crack in stainless that was airtight at 40 psi. diesel is the ultamate penatrating oil

 

[Wedg1e]

I've been in Non-Destructive Testing for 21 years and I have NEVER seen anyone remotely as attractive as that doing it!

 

[Maker]

Well it doesn't appear to leak so for round two, you should make a dodecahedron .

I've been in Non-Destructive Testing for 21 years and I have NEVER seen anyone remotely as attractive as that doing it!

What other non destructive tests are available that you do? You've mentioned a few times that you work with radioactivness, I'm guessing some kind of x-ray.

I see you're no longer "lord of Huckenbove".

 

[Wedg1e]

Well it doesn't appear to leak so for round two, you should make a dodecahedron .



What other non destructive tests are available that you do? You've mentioned a few times that you work with radioactivness, I'm guessing some kind of x-ray.

I see you're no longer "lord of Huckenbove".

Nursy gave me the title because whenever she caught me working on the car and I didn't see her coming, I seemed to say it quite a lot
A few weeks back I was fabricating some frames to hold some pipework, every angle was a bodge Mind you once they'd been filled with weld and galvanised, they almost look proper - and can be seen from any cross-channel ferry leaving Portsmouth

I'm primarily an x-ray service techie but work for a small firm so whatever the bosses take on, we have to do. We don't do as much with Gamma radiography these days (that's the stuff that will really kill you), x-rays are relatively safe as you can turn them on and off at will, so as long as you don't walk into to the primary beam, what could possibly go wrong...
Apart from radiography and DPI (Dye Penetrant Inspection) there's MPI (magnetic particle), Eddy Current, visual (which includes poking fibrescopes and miniature cameras into inaccessible places, some of the kit can do measurements as well), Ultrasonic (localised, or long-range for pipe inspection, this is where the big money is at the moment as the world's pipelines are largely 50+ years old and starting to fall apart).