How to achieve a non porous weld?

[clytle374]

I'm trying to TIG to steel pieces together for my injector tester.  The weld leaks like a sieve, is there a trick to this?  Or do I just suck that badly.

[mobile_bob]

what are you using for gas?
what are you useing for an electrode?
how did you prepare the electrode tip?
what filler rod are you using?

the answers to each will dictate success or failure

a proper tig weld will have no inclusions, no pit, pores etc.

i assume you are using pure argon gas
and a tungsten electrode? non thoriated iirc for steel.
the tip should be sharpened to a point,
the parts need to be ground clean of all scaled, dirt, feathers, and oil of course
the electrode should be powered with DC for steel and have a high frequency box as well
the tip should "Never" be allowed to touch the weldment, if it does remove the electrode
and regrind it to shape. the high frequency allows a non contact startup of the current into the weldment.
the filler rod should be very clean, no rust, no oil and not copper coated, just nice clean steel filler rod.

polarity from the welder is also important, one direction and you get penetration, the other you get top
weld with little to no penetration.

use a stainless steel brush to clean with prior to welding, use one that is specifically set aside for this purpose
that is clean and has no oil residue on it. stainless because you don't want little bits of rust flaking off and getting
brushed into the steel.

the rest comes down to technique, that is very hard to relate in a text format

bob g

[clytle374]

It is TIG.  Using 2% thoriated tungsten, was told that is what is needed for steel.  But I just read it isn't needed on inverter TIGs.  Was sharpened using the 'series of flats' method and not spun.    

Rod is copper coated ER31.  Never seen non coated wire.

Using DC, HF start.  Polarity is correct, welder doesn't allow you to screw that up.

I did stick the tip a couple of times and reground it.  

So I need new wired, maybe tungsten,  and to not suck.

[mobile_bob]

if everything is clean it should work fine,
have you tig welded before, or is this a new thing for you?

as for the filler rod, they make it copper clad and plain, i used to get the plain
as it was the preferred filler rod for the pipe line welders that did the root passes
on those high pressure natural gas lines back in the panhandle of texas, oklahoma and sw kansas

for the most part you can tig with a coat hanger filler but, tig welding so that it will hold
high pressure and not weep is another matter all together,

i suspect you just need some practice if this is new to you.

bob g

[WGB]

What are you grinding your tungsten on ? New clean dedicated grinding stone? You should really be using a diamond grinder made for tungsten grinding.
Start with silicon bronze rod very forgiving also takes shock better.
Oh and I'm no welder, but I do stay at Holiday Express I'm up to 45,000 points!

[clytle374]

I ground the weld off and could even see one big hole.  It was right were I stuck the tungsten before.  I guess the whole "it will contaminate your weld" stuff is the truth.

I have used a TIG welder quite a bit.  Never for anything pretty or high pressure.  Not saying I'm good at it.  I usually do okay and make a decent looking weld, but I have to use the foot petal.  The on/off switch, I never get the current adjusted right.  Same problem with a MIG, which I hate, and suck at.

I get a very small amount of seepage at around 80 bar so it isn't a problem.  The internal valve doesn't hold pressure and seeps, that is a problem.

I give you the RedNeck 3000 injector pressure tester. 

[Crofter]

Good advice all but a few points I see maybe not covered. If it is a DC capable machine you can select either the right or the wrong polarity. If you pick wrong your nicely ground point will immediatley melt to a ball. (that is deliberately done to form the ball shape for welding aluminum)

The advice is 100 percent on the cleaning of all rust or coatings on the metal to be welded but I still have seen circumstances where the weld would bubble and boil and fill with porosity and it was a problem in the metal itself and not procedure. Some free machining stock (such as hydraulic fittings etc are made of) will often bubble under the tig arc. They are not designed to be welded really but tig can be really fussy. I have had to give up and stick weld.

Another thing to watch for is any draght that might be blowing away your purge momentarily will induce porosity that is very hard to recover from. Another but long shot if it is a water cooled torch is an internal water leak

[WGB]

Also I've had bad gas!

[WGB]

I usually do okay and make a decent looking weld, but I have to use the foot petal.  The on/off switch, I never get the current adjusted right.  

I give you the RedNeck 3000 injector pressure tester.  

I didn't realize that people did off/on welding with TIG - as far as I knew it was either foot pedal or thumb control ...

Fine job on the RedNeck 3000 !






Jens

My first tig (still have) was set it and scratch start.

[clytle374]

I usually do okay and make a decent looking weld, but I have to use the foot petal.  The on/off switch, I never get the current adjusted right.  

I give you the RedNeck 3000 injector pressure tester.  

I didn't realize that people did off/on welding with TIG - as far as I knew it was either foot pedal or thumb control ...

Fine job on the RedNeck 3000 !

Jens

Yep, thumb.  Push on/ release off.  I cannot master that for nothing.  I was trying it as a learning experience for the situations I can't use the petal, but had to give up and use the petal.  I'm going to get a variable resistor like the one in the petal and make a jaw control. 

[WGB]

I usually do okay and make a decent looking weld, but I have to use the foot petal.  The on/off switch, I never get the current adjusted right.  

I give you the RedNeck 3000 injector pressure tester.  

I didn't realize that people did off/on welding with TIG - as far as I knew it was either foot pedal or thumb control ...

Fine job on the RedNeck 3000 !

Jens

Yep, thumb.  Push on/ release off.  I cannot master that for nothing.  I was trying it as a learning experience for the situations I can't use the petal, but had to give up and use the petal.  I'm going to get a variable resistor like the one in the petal and make a jaw control. 

That would be cool, I thought a wheel or guide you clamp on your wrist would be nice for us with the shakes too.

[clytle374]

That would be cool, I thought a wheel or guide you clamp on your wrist would be nice for us with the shakes too.

Not wanting to put voltage in my mouth, I'm thinking I'll use one of those plastic tubes inside of a plastic tube control rods for model airplanes.  Now if I just don't drool down the tube and get shocked anyway. 

[mobile_bob]

the combination of shakes, trifocals, and heavy breathing fogging up the lens
makes this sort of thing very difficult for me these days.

if you are not using this method of holding the torch, try holding it between a heavily gloved
fingers like a pencil, control is much better that way on small projects,

bob g

[WGB]

the combination of shakes, trifocals, and heavy breathing fogging up the lens
makes this sort of thing very difficult for me these days.

One of my 'would be nice' wish list items is a breathing system that flushes fresh air between the welding mask and the face because I can only weld for maybe a minute at a time before I can't see clear enough.
I also have magnifier inserts in my welding mask.

Jens

I made one out of a 3/4" OIL LESS dentist compressor, made for commercial air stones, dentist tools , etc., got it cheap!
Just set it up with a regulator & water trap, used 1/4" clear control hose like on magnahelic gauges, wire tied to the head band.
Air blows right on the lens, very nice when hot.

[Crofter]

The secret is to warm the welding shield up totally and you wont have the condensation problem.

I am into trifocals too and they are all but useless under a helmet as you commonly cant position to use the appropriate pane. I use a fixed focus set of reading glasses so I have the whole field of view and set up two helmets one with a number 1 and the other with a no 2 cheater lens. For most stick welding about two feet away the 1 and if it is more critical like tig, the number 2 so you can get up closer. Arc length and filler placement is critical for tig and you cant fake it-- you have to clearly see what you are doing. It doesnt get easier as you get older but there are lots of little tricks than can get you by.