Welding Tips and Tricks

I'm working on making a turbo manifold using sch40 304 1.5" pipe. I put a bevel on all the joints, wire brushed them with a ss brush and wiped down with acetone. I finally got my purge setup working so I don't blow out the weld but I'm not getting a nice narrow bead with good penetration and color. I can get color or full penetration but not all 3. I'm using a #17 with the big pyrex cup and gas lens setup.

CornerStone wrote:I'm working on making a turbo manifold using sch40 304 1.5" pipe. I put a bevel on all the joints, wire brushed them with a ss brush and wiped down with acetone. I finally got my purge setup working so I don't blow out the weld but I'm not getting a nice narrow bead with good penetration and color. I can get color or full penetration but not all 3. I'm using a #17 with the big pyrex cup and gas lens setup.

Welcome to the forum.
Getting color is normal and in fact unavoidable. For sch 40 your first pass should be getting the penetration, then a cap is the second pass. As far as the bead being wide, are you fitting up with a gap or butted together? What is the bevel angle?
A photo would be helpful

This is the bevel that the pipe has on it from the suppliers.

The factory bevel has too much land for me. I always dress it back to pretty much a knife edge. Root penetration is more reliable that way, for me at least. I will then run at about 85 amps, 2.4mm (3/32") wire for 1.5" sched 40 and get around it fast so as not to overheat it.

Awesome, thank you, I'll definitely keep practicing at it. I'm trying to build these manifolds for a business.

You're welcome. Don't forget everyone welds a bit different. You will find that what works comfortably for you will end up with settings and speed a bit different to mine so experiment to work out what's best for you.

I have noticed that I move a bit slower on stainless so I have been playing with the pulsing so I can work slower and keep the heat low to get the good coloring that I want and good penetration.

CornerStone wrote:I have noticed that I move a bit slower on stainless so I have been playing with the pulsing so I can work slower and keep the heat low to get the good coloring that I want and good penetration.

You are purging the ID, correct?

Yes, I actually had a problem not venting the end of the pipe and it would blow the weld out.

So I tried a shaper bevel and it worked out pretty good, still not getting 100% penetration but it was a gapless joint. Im going to try the next one with a .035 gap since that is the size of my filler wire.

CornerStone wrote:So I tried a shaper bevel and it worked out pretty good, still not getting 100% penetration but it was a gapless joint. Im going to try the next one with a .035 gap since that is the size of my filler wire.

What amperage are you using? Also on small diameter pipe, keeping the correct torch angle means you have to pay extra attention to this, it can be a challenge to keep the torch close to 90° as you move along the joint. Remember to keep the tungsten in close, if you draw it back you'll lose penetration and the bead will be too wide, small pipe will put you to the test of your TIG skills

Max amp was set at 130 (I believe I'm using about 90-110 amps on the pedal), I was using 1.2pps, I'll admit I didn't do the best job keeping the torch at 90* on the pipe.

First weld, pulsing at 95amps with .035 filler wire. Looked pretty good just concave. Knife edged bevel with no gap.

Same settings but tried going faster to get better color.

Switched to bigger filler wire to try getting a flush weld with the pipe. Still not getting 100% penetration and I had to run it to hot to get full fusion of the bigger wire and the pipe. This project is really kicking my ass.

This is what I'm aiming for.....

I think you should dump the pulse and you really should have a gap in your prep. Even 2mm will be enough. Use 3/32" wire and keep pushing it in till you fill the joint.

There may be some very skilled welders getting a bead like that in one pass but I have never seen it on sch 40 pipe. 95 amps should be plenty to get penetration, then your second pass with filler would be the cap.

In our shop we weld with no gap, however having a gap is very common. The weld procedure is different for both. The person who made the weld in your photo, are they in your shop, and willing to provide instruction?

When you say you tried for better color, the color actually represents contamination, although you can't weld this and have no color, more color is not a desirable goal.

Ltbadd, those are google'd images, I seen them before. Also, oxidation colors on SS are not contamination as they would be in Titanium, for example. In titanium and other highly-reactive metals, dark oxidation colors are indicative of varying levels of oxidation & embrittlement the parent metal and ultimately weaken and exacerbate the material properties that are sought after.

OP, you never practice on a project. I hope those aren't the actual pieces if you are that dis-content with them.

Oscar,
Who ever told you that the colorations while welding stainless were not contamination? It is and it should be avoided if possible. It's not as detrimental on stainless as it is on Titanium, but it still should avoided by using low heat input and good gas coverage during and after the weld. Any time steel goes through it's critical temperature range without gas coverage it will oxidize and discolor.

If you want to test this, light up on a piece of stainless or carbon steel for that matter and form a puddle and don't move the torch until it cools for about 10 seconds and it will be shiny bright. Do the same and move the torch away immediately and it will turn dull gray or purple.

Len

Yes, those are Googled images just to show my end goal. From what the guys That produced these types of welds are saying, it's sch 40, single pass with 100% penetration. Honestly I'm more concerned about getting 100% penetration and a good flush weld. The reasoning behind the coloring from what I understand is that it helps show the HAZ was not to great because 304 doesn't like excess heat. Like the googled images the blue/purple is sort of what everyone doing this work produces. And no I'm self taught tig welding, I do it solo out of my personal shop and my day job I use a scratch start little miller for doing stainless welds in a food plant.

CornerStone,
I can hardly believe that you could weld 1 1/2 sch 40 fittings together with full penetration in one pass without putting a ton of heat into it. It's 0.145" wall thickness and with a knife edge and no gap the weld would end up almost 5/16" wide. I wouldn't expect it to be lacking on color or have a narrow HAZ when you're finished. I would think you co do it in two passes and end up with less heat input. That's just my opinion, I don't have any sch 40 1 1/2 here or I would give it a try.

Len

Won't be around this weekend but next week I'll be trying several different techniques to get the results I need.

I tried 1 pass schedule 40.…it can be done but like mentioned it put too much heat into the joint, I welded fast and pushed a lot of material in, was a lot more flush then the joints you showed, 3/32" gap, 3/32" tung, 3/32" filler and 105 amps I believe.

To get proper results I use the gap mentioned above, put a nice root pass in and then basically a hotpass cover.

Post the results!

Got home today so I'll try those settings tonight after work