Outside corner SSSS

[DecK]

Have not had as much torch time as I'd like but had to make this up today. Its a shoot for feed from a hopper to feed cattle. Had to do the bending myself so fit up wasn't the best and had to regrind the tungsten more than a few times. Any comments/ insights/ insults welcome

Had the foreman keeping an eye on proceedings

This is it in place. Its only a quick repair as the whole place is being refitted come autumn

As mentioned earlier, any comments welcome

 

[steviec_lj]

It works a serves a purpose.

Far better than my TIG welding too!

 

[DecK]

Well at the very least it gave me a bit of practice anyway. As I said, come Autumn the whole place is getting a re-fit and there'll be 16 or 20 of these to be made. That one took me 2 1/2 hours today but a lot of that was cutting and shaping the two pieces to size. Think I'll have to make a sheet bender to speed the whole lot up . Left a few hammer marks on it today that upset me when it was finished

 

[Richard.]

Did u purge the inside. Hard to tell from photos.

 

[DecK]

No. Didnt purge the inside because I didn't have a second line from the argon and also because I didn't really think it was necessary. It was only to replace a shoot that was completely shot and was no more use. Once refitted in Autumn the likelyhood is this shoot will be going as well as it will more than likely be too short and cut and shaped to the wrong angle for the new hoppers.
Being honest, this was more to see if I could actually stick the two pieces together never mind getting a decent weld. Got quotes of 50 to 75 quid a piece from local crowds just to fabricate something similar outside material cost. After having a go myself I dont actually think the price is that bad for the time it took but my time is a lot cheaper.

 

[Richard.]

Well the weld appearance is very good. If you do end up making another which I'm sure you will. I would advise an inside purge or don't penetrate right through. This will make your shoot last a life time. If not corrosion will take it's toll and you'll end up replacing them. Stainless ain't cheap and you may as well take advantage of what it offers ie corrosion resistance. You've done a decent job of of it and cleaned up the surface welds which is good. A permanent one in autum would be spot on if you can get away from the inside sugaring. Well done mate.

 

[DecK]

Well, how would you purge the inside? Ideally when I'm making the finished ones I would make them out of one piece with three bends and one join. Would it be worth getting a ready made purge block or seal one end up and try and fill it with argon. The shoot is 3 1/2" X 2 1/2" and 18" long. I suppose to seal one end and fill it with argon would save having to move a purge block mid weld or am I overthinking the whole thing.

 

[Richard.]

Even with one weld I would still purge it If it's to penetrate through or it will corrode.
I block a lot of my ends off with that metallic tape. It is great stuff. What I would be looking at with that job is welding it in such a way that you don't need a purge. These welds are purely to seal it together they are under no load or stress. There is no need for full pen. Concentrate on tight fit up. So that the edges touch tight all the way then reduce your current till your welding it nicely but not going through. You'll still get the oxides on the back (heat tint) but it looks roomy enough in there to clean them off. That's what I would do with that job as I believe the weld will be strong enough as a surface joint.

 

[Richard.]

Not bad folds for a bit of hammer work I must say.

 

[DecK]

Cheers for the info. Can't reduce amps any more though. Did those at the 30 amp minimum on the newarc. Only thing is that the main box was 1.2mm and the top piece was 0.8mm I think so going for 1.2 all around may help with the penetration issues. I have some of the 1.2 left over so I can have another go on that and see how it works out with a 1.2 to 1.2mm join and drop to a 1mm tungsten. If that fails I can go up a size in the stainless.

Not bad folds for a bit of hammer work I must say.

Well... you know what they say... If at first you don't succeed, get a bigger hammer

 

[Richard.]

30amps is about bang right for 1.2 and yes it will go through the 0.8 . Fit up is key if your to try not getting through it. So that's where I'd be looking to perfect the job. 1.2 all round with good fit up is very doable At 30amps to get a nice weld right across without getting through. If you cannot do it then block off the ends with metal tape and give it a feed inside of argon. Get it right and that shoot will serve you for many years.

 

[Paul.]

You can clamp a piece of stainless bar tight to the inside of the joint, it will act as a heat sink and also protect the back of the weld from the atmosphere to a certain extent, I often do this when welding tank bodies that would be difficult to purge, look at the first picture in this thread, this is exactly how I welded them, the inside was then pickled and scotchbrited to get rid of the heat tint, but there is no coking at all
http://www.mig-welding.co.uk/forum/threads/wash-tanks.45453/

 

[Richard.]

Nice method Paul. I'd imagine the heat sink on the back plays a good part in distortion reduction also.
Saves on gas, and eliminates the coking. Looks like a Winner to me.

 

[DecK]

Sound man. As I said have some of that 1.2 left over so I'll have a bit of practice on that and see what I can manage.

You can clamp a piece of stainless bar tight to the inside of the joint, it will act as a heat sink and also protect the back of the weld from the atmosphere to a certain extent, I often do this when welding tank bodies that would be difficult to purge, look at the first picture in this thread, this is exactly how I welded them, the inside was then pickled and scotchbrited to get rid of the heat tint, but there is no coking at all
http://www.mig-welding.co.uk/forum/threads/wash-tanks.45453/

By stainless bar do you mean solid square section ? 1/2" or 1" square or so.

Also, I was thinking would it be better to do it autogenous or would that just give a weld with very little strength?

 

[Richard.]

A length of square or rectangular bar preferably solid I believe he was meaning. Needs to be a decent bit as it must suck the heat out of the joint. This will help a lot with the thin material and excessive pen.
You could do that autogenous I don't see why it would not be strong enough but if you don't have spot bang bob on fit up for that then you will put a hole in it.

 

[Paul.]

A piece of flat or angle will do, you're only trying to protect the back of the joint, there are various ways of doing it, fold a piece of sheet double to give it some thickness then tuck the radiused edge created by the fold into the corner, or another method, flatten a piece of copper pipe to make a flat strip, aluminium can be also be used but not my first choice, avoid steel or you will get contamination

 

[Richard.]

A piece of flat or angle will do, you're only trying to protect the back of the joint, there are various ways of doing it, fold a piece of sheet double to give it some thickness then tuck the radiused edge created by the fold into the corner, or another method, flatten a piece of copper pipe to make a flat strip, aluminium can be also be used but not my first choice, avoid steel or you will get contamination

Is it more for protection from atmosphere Paul than a heat sink?

 

[DecK]

Cheers lads. Just learned more in the last hour than the few nights reading before I started this. Nothing better than first hand knowledge.
Main thing anyway is to get the fit up bang on and get a piece in to support the back and provide heat sink/ protect from atmosphere

 

[Paul.]

Accurate Joint setup will help too, use a closed corner like this rather than an open corner, it will help to avoid over penetration

If you do ever need to purge something like that there is no need to fill the whole thing with argon, make some purging bars from sheet or you can even use heat resisting tape then stick a purge supply up it from the end

 

[Paul.]

Is it more for protection from atmosphere Paul than a heat sink?

A bit of both really, if you've never tried it it set one up and see the difference in appearance, its not a substitute for a full purge by any means, but for non critical work is an easy solution.