on Schedule 40 piping... to get good peneteration, i would want to make 2 passes correct?? i find the thicker stuff is hard to penitrate for one pass. can u give me any advice?? thanks man

 

I would NOT try to weld it in one pass. To do it in one pass, you're running so hot that it's harder to control and likely destroys some of the properties that the metal should retain after welding.

I would reccomend at least 2 passes.

Here's a larger pipe, thicker, and it's carbon steel, but it gives an idea of about how much your root pass should fill your bevel.


The pic below is 245SMO, which is a really high grade of material, similar to stainless. You can see that the puddle is a bit trashy, but welded correctly, it does ok. This was on pipe about 2" diamater. Near the bottom of this pic, you can see what is the most popular way to fit pipe. The gap is just slightly less than the diameter of filler wire. This allows you to just lay the wire in the gap and melt over it, blending it into the sides of the bevel just slightly. Also notice that I ground the tacks down so that I can burn through them or consume them in the weld as I approach them.


This next pic is after the root pass. Notice on the side and the top it's a little lumpy. This is where I had to run over or burn through the tack welds.

 

Off topic but what is up with the organe tape ?

 

It prevents the purge gas from being wasted.

Back purging is something that is so overlook by many people who are welding tubes. It therefore becomes a question of when will it break versus if.

 

As Dave stated, it holds in the gas purge. Without it, while welding joint "A", joint "B" would be leaking out my argon...and letting oxygen in.

Ever weld on a thin stainless plate and see all the black stuff that it pushes out on the back side? If header is welded without a purge, and the inner walls are penetrated, this black stuff will be inside the pipe.

 

Here are some pictures

https://honda-tech.com/zerothread?id=588002

 

good info as usual

 

what kind of an orange tape is that? is it special? I mean special meaning that it wont melt while welding?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by snoochtodanooch &raquo;</TD></TR><TR><TD CLASS="quote">good info as usual </TD></TR></TABLE>
Yeah, but you don't have to use the high dollar stuff. I used it on that job because they had it there...and they paid for it. Most places just use masking tape. You just have to be more careful and not get it hot.

 

That tape looks like vacuum chamber tape. VERY expensive stuff if it is. Highly temp and degassing resistant.

edit: grammer

 

OK its time to pick your brain a little more Engloid haha. How can i set up a purge while welding my 90 bends togther for my manifold?? Whats a cheap and efficient setup?? Also can u explain to me how you would weld schedule 40 togehter? Like How many amps you would slam it at max. If you could just write a short step by step on how u would approach it,like for example.

step one- I run a bead across the two pipes at 50 amps max going very slow just to penetrate through and hold the 2 pieces together.

step two- I run another bead over that one with some filler to add sturdinest.

ect...ect... thanks in advance man

oh yeh one last thing, my welds look grayish, its not colorful like the other ones i see online. But as soon as I clean it off with the wheel it lookes nice again, still no color but nice and shiny,am i going too fast or too slow?? Ive tryed to go fast and slow but still gettin that grayish weld.

 

I have a question as well. In your post Engloid you said a popular way to fit pipe is to have a gap a little less than the diameter of the filler you are using. Excuse my ignorance but everything Ive ever been taught or read has always strongly stated that you should not have ANY gaps on your fitment. This logically tells me that if you try to use filler to close a void that the weld will not be nearly as strong as a weld placed on two pieces that are precisely fitted.

comments/input?

-bill

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AutoLab &raquo;</TD></TR><TR><TD CLASS="quote">I have a question as well. In your post Engloid you said a popular way to fit pipe is to have a gap a little less than the diameter of the filler you are using. Excuse my ignorance but everything Ive ever been taught or read has always strongly stated that you should not have ANY gaps on your fitment. This logically tells me that if you try to use filler to close a void that the weld will not be nearly as strong as a weld placed on two pieces that are precisely fitted.

comments/input?

-bill</TD></TR></TABLE>

Well whoever has told you that is crazy. Go to any pipe fab shop and youll probably be fired the first time the job steward sees you try to install something that hasnt been gapped...

I am about to post an very long and informative post. I do the same stuff engloid does everyday...

&lt;--- Local #166 Union Welder/Steamfitter/Pipefitter

 

ya in my welding class we have to bevell the edges and we have a jig consisting of vise grips and a peice of wire in the meiddle to ensure tthat the gap is just the right size

 

1. Clean the base metal of all slag, paint, grease, oil, moisture, or any other foreign materials. Make sure that you do not rind into too the bevel too much, or when you gap the pipes they will fit crooked. This must come before ANYHTING...


2. Gapping/Fitting the pipe.

You will do this by taking a piece of filler rod that your using to weld with a bend it like so:



You will use this to gap and fit the pipe. Normally you would be doing this with pipe stands, but i dont think any of you have these. When you gap/fit the pipe you will stick the gap rod in between the 2 pipes like so:


(say thats looking driectly through the pipe)

Now when you do this your probably wonder how to get the pipe lined up properly, buy a magnetic "torpedo" level and use it like so:



Now the pipe has been properly fitted and gapped. YAAY for you, if you want take a trip to Hawaii. Make sure the pipe doesnt move though.

3. Tacking the pipe in place:

You will take the pipe in four different places, and after each tack if you want to properly do it, you will you the level each time moving the pipe till its level and true with each other. Then after you are done tacking the pipe you will take a grinding wheel and grind the tacks down as Engloid did. This is so the tack will be consumed by the root pass better and will in turn produce a more consisten weld, of course if the human error is removed...


4. Root pass on pipe:

You will lay your filler rod in the gap and after you start welding you will be able to move the filler rod going with the weld. This isnt hard and i wont draw an illustration, all you have to do is lay the filler rod in the gap/bevel. After the root pass is complete you will clean it up with a SS wire wheel.

5. Cover pass:

This will be more of a cosmetic/structural pass with the root pass being your selaing pass. On the bigger pipe you'd be "walking the cup" which i can bet youve heard of with me and Engloid going back and forth trying to explain how its done. There is a thread, just search. With this small pipe it will be mostly welder skill on making this pass look good.


This is the proper way to weld pipe. I could go into FAR more detail and i will if more questions arise.

Also, there is really no set amperage when you are welding, there are only guidlelines as every machine is different. As for the grayness it could be the gas, are you using 100% AR?

 

yes it is 100% argon, sometimes i can get color but most of the time i cant, cant figure out why. i am using 1/16 308 stainless rod

 

post pics is the only thing i can say. btw did the above help at all?

 

what should my gas be set at?? i think its around 22 it might be high i think. thanks untitled

 

22 hrm... i say turn it up in increments by 5 and test it out on some spare metal and see what works best. EAch setup is different, but pics would be VERY helpful to see whats going on.

 

1) Grind a bevel on the pipe. The bevel that's on the elbows when you get it is not very precise or consistent. Grind a bevel that leaves about 1/16" "land". The Land is the amount of flat area that is not beveled.

2) You can use simple stuff to purge the pipe. You can use one bottle with a splitter like in this link: http://store.weldingdepot.com/....html
From there, get a fitting similar to this one:
http://store.weldingdepot.com/....html
It will screw into the splitter, which screws into the bottom of your regulator or flowmeter. Your hose to the welding machine goes to the other side of the splitter. Then you can run the hose for your purge directly into the end of the pipe (not the end you're welding) and use masking tape to seal it up. You can also use things like a rubber ball with the hose put through a hole in it, aluminum foil, or whatever else you want to seal the pipe with.

3) In the beginning, butt them together with no gap. Put 3-4 small fuse (no filler) tacks around the pipe to hold it in place during welding. Don't try to burn through during this, especially if you don't have your pipe purged up yet. Later, after you master this, you can step up to gapping the pipe on the root pass.

4) You need to make sure that any gaps in other fits, open ends, etc are all sealed up. Typically you want to put your purge in at the bottom, and then on the high point, pop a hole about 3/8" diameter. Imagine that you're filling the pipe with water, as argon is heavier than air. If you have a hole in the bottom, the pipe will not fill up, it will just let the argon out the bottom.

5) You want to run about 15cfh of argon in the beginning when you're still learning this. Additional argon will help the internal color, but that's all. Conserve your gas and use it when it matters, but for now, just try and get consistent penetration.

6) Give the pipe about 3-5 minutes to purge up (would be longer on bigger pipe). If you can hold a lighter at the vent hole and the flame keeps burning, then you havn't purged it long enough. That is not so say that as soon as it puts the flame out, it's safe to weld...as it will take a few minutes at least.

7) I'm really terrible at estimating the amperage you will need, because I learned to weld pipe on a machine that just had a round **** with no numbers...clockwise added heat. I still weld like that, except I turn the machine way up and use the remote to control amperage. However, I'd estimate that you will need about 65-80 amps. This will vary, depending on the angle of bevel you have, and amount of land. You can adjust your land in the future to your needs. If you find it hard to burn through at the amperage you want to run, leave less land. If you find you're burning holes in it at the amperage you want, leave more land. In other words, the land is there to help you control the heat input on the root pass.

8) For your practicing, you can actually use straight pipe and tape a clear lens over the end of it. Have a friend look in the inside as you fire up the torch. Hold it in one place and slowly increase heat until your buddy says you burned through. Let him talk you through it and tell you how it's looking in the inside. You want it to just melt, not push deeply inside. You can adjust heat and speed according to what he's telling you. You typically will want to "quarter-weld" pipe. This means to weld 12 oclock to 3 oclock, 6 to 9, then the other two quarters. Basically, you're alternating quarters. This is done to minimize the pipe drawing one direction or another.

9) After welding all the way around it, cut your purge down to about 5cfh and save argon...you're just practicing now and color isn't your goal now. That's enough gas to prevent sugaring, but don't be upset if it's a little dark when you look in there later.

10) LET THE PIPE COOL. Brush the pipe as it cools. The coloring is oxidation and will interfere with your next weld pass. Most welding codes will require an interpass temperature of 350 degrees on stainless. This means not to weld it if it's still over 350. If you want to get technical, you can use a "temp stick." Here is a page with them, in various temperature ranges: http://store.weldingdepot.com/....html
You take this stick, which looks like a big crayon and you touch it to the pipe at a point 1" from the weld. (If this is a showpiece, don't do this, as it will leave a mark that will have to be polished or ground off.) If it melts, then the pipe is hotter than the rating on the stick. During cooling time, you can put the root in another weld joint, smoke a joint, or whatever you want.

11) You now have the root pass put in and have let it cool. On the second pass, it's not really important to quarter weld the pipe. It won't draw much now that the root pass is in already. Hold your tig torch in the place you intend to start welding. Fire up and increase heat till you get a nice puddle. Put your tig wire in the puddle, but DO NOT take it out. If you put the wire in the crook between your thumb and forefinger, without squeezing it, you can turn your wrist and use a slight leverage to press the wire down to the surface of the metal. This will help you to hold the wire steady. You may need to bump heat up a little at this time, as adding wire will decrease heat of the puddle. Now, do very small zig zag motions to put a FLAT bead IN the bevel. Try not to even burn the top edges of the bevel on this pass. Make sure to tie the weld into the sides. Notice the pics of the root passes I posted above. There's no small cavities on the sides or anywhere that could get covered up with the next pass and leave a small spot of porosity (empty hole IN the weld). If you burn hot enough to melt through the root, you're too hot.

12) Let the pipe cool again. Brush again.

13) Now you have the weld flush with the top or close, and it's time to put your cap pass on the weld. By this time, you can turn your purge off. If you burn through the root, you're way too hot. Color may still change on the root, but you're just practicing and color isn't important now.

14) Again, fire up your torch in the location you want to start, form a puddle and put the wire into it. Do a zig zag pattern again and just melt the wire down so that it just barely covers the top edges of the bevel.

Notes:
If you're really wanting to conserve gas, shut it off after welding the root pass. If you burn through it again, you're welding too hot. You can also open up the pipe after the root pass and inspect the weld, but if you want to keep it a nice color you will have to retape it and give purge time again.

You may be able to weld this pipe with 2 passes, eliminating the second pass, but that will depend on your technique, the amount of bevel you have to fill, and other things. So don’t be stuck on having to weld with 3 passes, but odds are you will want to do this in 3 passes until you get used to leaving the wire in the puddle and actually feeding a little bit.

Typically, when tig welding, you can look at amperage like it's a ratio of heat to speed of travel...but is also influenced slightly by the input of wire (try welding with 1/8" wire and you will see what I mean.) As a beginner, lets say you're welding at X inches per minute. You will want your heat to allow you to run only that speed, no faster...and you don't want to be waiting on the puddle to catch up to you either. As you learn and get better, you will run your heat a little hotter than you can go fast...and this helps to make the metal flow more smoothly and reduce any bumps and lumps.

The gray color you’re getting is a result of either bad gas coverage or going too slow for the amperage you’re running. It may also be that you’re not letting the pipe cool…another thing that can overheat the metal and give bad color.


There are different methods that are used by different people, different applications, and different employers with different welding procedures. Typically, the jobs that Untitled and I have worked, the pipe MUST have a gap. Most common is 1/8" with a + or - of 1/16". This means anywhere from 1/16" to 3/16" gap. Keep in mind that this is on pipe, not thin walled tubing. I am recommending to weld without a gap only as a method of learning to weld on this pipe. With thin tubing, like 16 gage, you would not bevel or leave a gap…and gaps are much harder to contend with. After getting the idea of this gapless method, I’d recommend stepping up to the method of gapping it with a gap just slightly less than the wire diameter…as you mentioned.
Granted, fusing the root as I’m recommending will make a weld plenty strong enough, theoretically you weld would be stronger when gapped and adding filler metal. This is because your filler metal should be stronger than your base material. For example, you usually will weld 304 pipe with 308 wire, which is stronger.
Yes, good point. If you want a gap just slightly smaller than 3/32", you can bend a piece of the wire like Untitled has in his pics above. When you tack them together and pull the wire out, the pieces will have drawn together just slightly, sometimes making it necessary to pull the wire out with pliers.

Also, I’d add that although you may see slight differences in what I and Untitled say, I can and have welded things exactly as he says…and often do, depending on the application. Nothing he’s said in this thread, do I disagree with. There’s many ways to do things and in time you will develop your own techniques. It’s about like how you learned some things from your dad, some from your mom, some from friends…and you put them all together and made your own personality. The same is true with welding. In the end, you won’t be far off from everybody else, but you will have slight differences. On EVERY pipe welding job I’ve been on, some guys wanted a small gap and some wanted a big gap, while others just didn’t care and would weld up anything. Myself, as long as it’s in an acceptable range, I will weld it.

 

WOW. i have never seen it done like that... Holy bejesus!!

I geuss thats the difference between unions... im only in 2 years...

 

can someone host pics for me?? i got the pics but dont know how to post them

 

When I get the puddle started, it stays pretty small unless i slam on the pedal, should i make my circle puddle bigger by doing a circle motion with my torch or should I hit the pedal harder??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fullblown &raquo;</TD></TR><TR><TD CLASS="quote">When I get the puddle started, it stays pretty small unless i slam on the pedal, should i make my circle puddle bigger by doing a circle motion with my torch or should I hit the pedal harder?? </TD></TR></TABLE>
I'd just add more heat. I probably have only done any circular motion in about 1% of the welds I've done. I use heat or a side to side motion to get a wider puddle. I can probably host a few pics for you for a while...just save copies of them in case I delete them someday. You can email them to EngloidATdespammed.com

 

ok pics are sent. if you could critic them for me and the rest of the guys who are interested, id appreciate it