TIG advise for 1.5" Sch10 Pipe

[T0A0C]

Hi All,

I've just purchased my first TIG machine. I'm planning to build a turbo manifold and do some exhaust work.
I have done a small amount of TIG welding back when I did my apprenticeship but that was some 10 years ago now but I've done a lot of MIG in recent years.

Been practicing on some off cuts but I have some questions on how to tackle the actual welding.

The pipe is 1.5" Sch10 with a 2.7mm wall thickness 304L.



Firstly, I'm getting a small amount of grey film form on the weld. I'm guessing this is a bit of overheating due to the size of the off cuts. Ive tried to turn the amps down and added a bit of pulse to keep the heat input minimum but I still get it a bit. Will this be a problem when I weld the larger pieces. Or will they dissipate the heat better?

The next thing I need to know is if should do this in one pass. Or fuse the root then cap. I've done the above with no filler just fusing, will I even need filler?

Any help much appreciated!

Thanks

Tom

 

[Richard.]

It's a Fine line with thin walled SS .
Grey dull welding is a classic case of too much heat/poor shielding.
If your after the desirable shiny welded finish reduce your heat input and ensure you've got adequate argon blanket over the weld. Turning down the current doesn't really reduce your heat input. Your better off using a current to weld it properly and reduce your heat by travelling faster. Turn your current up if you like and in turn this will force your hand to travel and fill much faster. A gas lens makes a difference with exotic metals and there welded appearance. Tiny shreds of metal in the vice are not really the best to be trying on.

 

[T0A0C]

Thanks for the reply Richard, I'm not all that bothered about the look. My main concern is the strength as its going to have a turbo on the end so it needs to survive a bit of stress. I will give the higher current faster movement a go on some larger pieces. Got the machine at 80 amps so will try some small amp increments. Got a gas lens on order should hopefully be on by Friday

 

[Richard.]

The best attitude if you ask me and one that's rarely adopted by people making SS exhaust parts. The usual trend is pretty colours 1st followed by soundness of the joint so I'm pleased to be talking with someone with there priorities right.
If your after a sound joint in stainless steel you need to fully penetrate and you need to protect the root on the other side. With exhausts and tubing this is usually done with an inside purge.
2.7mm is a decent thick gage. 80 amps is on the hot side for it and will certainly get you traveling. I'd be putting a little prep on the joints and be more around the 60-70 mark and I don't hang about. 1.2-1.6 308 filler. 1.6 tungsten , very short arc is key and often the problem with lots of dull SS welding if arc length is too long. Gas flow 6-8 lpm.

 

[T0A0C]

Haha good to hear, I already plan on ceramic coating it black so there wont be any pretty colors there. Got my self a Y piece of the regulator at the weekend so just need to make the piping for the purge and get a lens of sorts for the purge pipe.

I have the 1.6 tungsten and filler. 316 filler though so hopefully that will be okay.

I think I may practice getting the arc length down a bit. I was finding the sides of the bevel started to puddle and I had to hang about a bit waiting for the middle to puddle probably due to the length. Will try the 60-70 amps, I'm assuming that's with no pulsing?

Thanks again for the good advice!

 

[Gizmo.Y]

Doing the same as me...

2.4 filler, 50 ish amps iirc

 

[T0A0C]

Yeah, that looks like the stage I need to get to. What made you decide on a 2.4 filler rod? Is it to help with heat?

 

[Richard.]

Yeah, that looks like the stage I need to get to. What made you decide on a 2.4 filler rod? Is it to help with heat?

316 filler rod is fine.
No I rarely use a pulse personally and if I did it would be for really thin gage SS. If you want to pulse you need to set your max and min currents so that your average welding current is where you want to be. Eg if 60 amps works set your min at 20 and your max at 100.
2.4 filler is way too thick for that current level.

 

[T0A0C]

Hey all,

Thought I'd put a little update on my progress with this.
I've been putting the hours in locked away in the garage with the welder.

Got the manifold mocked up and tacked:

Then Broke it apart and welded the inside of the collector:

Then did some of the welds on the large pipe after the collector:

And here's the runners after they've been broken off and individually welded

And here it is completely mocked up on the engine

All in I'm happy with the progress so far. Next up is the finishing welds to the collector. Still not sure how I'm going to get the access to weld each runner but I have a backup plan!

 

[mikejack]

no pics showing for me !

 

[mechman]

no pics showing for me !

Nor me

 

[T0A0C]

Who knows, wont seem to upload properly.......

 

[Paul.]

I suspect that the image files are too big, I can see them ok on my monster home pc, my work laptop struggles with them and the phone gives up altogether, try reducing your images size before uploading they dont need to be 2 meg to display on the forum, here's one of them resized to about 50kb

 

[shambo]

That BBW cup though...

 

[Richard.]

I have had most of them pop up eventually on my phone
I can't get your resized one at all Paul.

 

[dobbslc]

Nice work! I'll eventually be doing an exhaust for my bike but I think I'll lots more practice......

 

[Richard.]

That BBW cup though...

Not needed at all for stainless steel. To use such a thing you need to flood (waste) gas in order for it to be remotely effective and a no7/8 can achieve perfect results with lower flow rates. It's all I ever use.

 

[T0A0C]

Not needed at all for stainless steel. To use such a thing you need to flood (waste) gas in order for it to be remotely effective and a no7/8 can achieve perfect results with lower flow rates. It's all I ever use.

...................................... But the BBW lights up as you weld

 

[Richard.]

...................................... But the BBW lights up as you weld

Oh I didn't realise that.
Absolutely essential then

 

[T0A0C]

Oh I didn't realise that.
Absolutely essential then

Haha no maybe not but I was struggling for a nice coverage on the 3" pipe so I got the huge lens just for that part. All the smaller pipe was done with the smaller gas saver CK kit which runs at a much more efficient 15CFH.

I still cant for the life of me figure out how to weld all 4 pipe's into the collector. there's about 10mm of space between them and this gives me the first issue of my angle been almost side on with the tungsten to the pipe. Then the second problem of if i stick the tungsten right out I get no gas coverage and it turns into a firework display. Anyone have any ideas?