Tig welding tips, questions, equipment, applications, instructions, techniques, tig welding machines, troubleshooting tig welding process
I've been tasked to weld 3" .065 wall Stainless 304 but have a hard time not overheating the metal. I can't lose the corrosion attributes of SS since this piping will be outside and used for a food grade lubricant. I'm using Lincoln Precision TIG 225 and purging the pipe with Argon. What advice can you offer?
- Otto Nobedder
-
Weldmonger
-
Posts:
-
Joined:Thu Jan 06, 2011 11:40 pm
-
Location:Near New Orleans
After your initial heat to begin the weld, you'll likely be around 35A or less for a section that thin. There are several people here who do food-grade work, and will give more specific advice.Shannon wrote:I've been tasked to weld 3" .065 wall Stainless 304 but have a hard time not overheating the metal. I can't lose the corrosion attributes of SS since this piping will be outside and used for a food grade lubricant. I'm using Lincoln Precision TIG 225 and purging the pipe with Argon. What advice can you offer?
I'm going to move your post to the TIG forum, where it belongs, and will see many more responses.
Steve S
The basic technique is still the same---the weld bead needs to be flooded with argon until the base material has cooled sufficiently to not oxidize in the atmosphere. How long the argon coverage needs to linger depends on your active effort to wick heat away. Use no heat-sinking and you will find yourself needing to run multiple smaller bead lengths to avoid heat build-up while simultaneously needing to use a larger than normal cup diameter. So that begs the question: how are you planning on actively wicking the heat away by artificial means?
Thanks for your help. I am using a number 8 cup, 1/16" 2% thoriated tungsten and have played with the use of .030 308L MIG wire. I don't have a lot of options for cooling but have tried wet rags wrapped around the pipe near the weld. As long as I get good penetration is a narrow weld bead okay? Also, since the material is so thin, is there a recommended gap between the two pieces?
-Shannon
Hi
- I would try welding with pulse. It will decrease your heat input and when set right you will get at least same penetration. In some cases even deeper.
- Walking the cup also helps on color as your puddle will be longer in argon shield.
- Check that you don't have any leaks in your gas lines etc. Oxygen in shielding gas creates nasty welds!
- Make sure your metal is clean from oils etc.
I do orbital welding on food grade pipes and also on pharma. I wouldn't worry too much about the color on surface, if your machine doesn't leak gas and pipes are clean.
Surface color is just thickened oxide layer that have reacted with oxygen in high temperatures. Nothing else. There are people who say that your weld should be pink after welding, otherwise you have cooked all chrome away. That's is not actually true. Only the surface have reacted with oxygen and lost some of it corrosion resistance, due it's nature of porosity etc.
So how to get rid of that heat tint. There is only two right ways to fully recover the surface. Pickling and electrolyte cleaning. You can always wire brush or grind that surface down and it will help, but on corrosive atmospheres only chemical pickling (or electrolyte cleaning=same principle) will work.
- I would try welding with pulse. It will decrease your heat input and when set right you will get at least same penetration. In some cases even deeper.
- Walking the cup also helps on color as your puddle will be longer in argon shield.
- Check that you don't have any leaks in your gas lines etc. Oxygen in shielding gas creates nasty welds!
- Make sure your metal is clean from oils etc.
I do orbital welding on food grade pipes and also on pharma. I wouldn't worry too much about the color on surface, if your machine doesn't leak gas and pipes are clean.
Surface color is just thickened oxide layer that have reacted with oxygen in high temperatures. Nothing else. There are people who say that your weld should be pink after welding, otherwise you have cooked all chrome away. That's is not actually true. Only the surface have reacted with oxygen and lost some of it corrosion resistance, due it's nature of porosity etc.
So how to get rid of that heat tint. There is only two right ways to fully recover the surface. Pickling and electrolyte cleaning. You can always wire brush or grind that surface down and it will help, but on corrosive atmospheres only chemical pickling (or electrolyte cleaning=same principle) will work.
-Markus-
Forgot...
Don't use any gap! You will let oxygen inside the pipe and root will get discolored.
Narrow bead is OK, if there is enough penetration.
In some grades or even between patches you are able to get more penetration with narrower bead. It all depends of the alloying elements and how those change the weld pool flow direction.
Also about those alloying elements.... Some will act more easily with oxygen and therefore those will create darker welds. Molybdenum for example can affect to this.
Don't use any gap! You will let oxygen inside the pipe and root will get discolored.
Narrow bead is OK, if there is enough penetration.
In some grades or even between patches you are able to get more penetration with narrower bead. It all depends of the alloying elements and how those change the weld pool flow direction.
Also about those alloying elements.... Some will act more easily with oxygen and therefore those will create darker welds. Molybdenum for example can affect to this.
-Markus-
Markus,
Thanks for you help, I think that gives me good direction. I know each machine runs a bit different but previously Otto mentioned an amp range near 35, with pulse would I need to bump the amps up a bit and is 20 hz a decent pulse? My machine only pulses up to 20 hz. I like the idea of using the .030 308L mig wire because it allows me to keep the puddle smaller (less heat), is that a proper solution or should I buy some filler wire?
Thanks for you help, I think that gives me good direction. I know each machine runs a bit different but previously Otto mentioned an amp range near 35, with pulse would I need to bump the amps up a bit and is 20 hz a decent pulse? My machine only pulses up to 20 hz. I like the idea of using the .030 308L mig wire because it allows me to keep the puddle smaller (less heat), is that a proper solution or should I buy some filler wire?
-Shannon
Yup you need to raise amps a bit and I would set lower amps to about half what high amps are. 50/25 Amps for example.
There is many ways to adjust your amps and pulse time. Hertz sucks, because those are so damn hard to get right and adjust the way you want. It will take some to to get use to it.
y5di20Mtlpk
308 mag-wire is suitable I guess, but not sure. If the job is really critical I would buy Tig wire instead.
There is many ways to adjust your amps and pulse time. Hertz sucks, because those are so damn hard to get right and adjust the way you want. It will take some to to get use to it.
y5di20Mtlpk
308 mag-wire is suitable I guess, but not sure. If the job is really critical I would buy Tig wire instead.
-Markus-
Great! Your advice was successful and much appreciated. Good penetration and controlled heat with the pulse. I'm only using a #8 cup so I'm running shorter beads but plan to pick up a larger cup tomorrow. Thanks guys!
-Shannon
Great to hear it worked Add some pics, if possibleShannon wrote:Great! Your advice was successful and much appreciated. Good penetration and controlled heat with the pulse. I'm only using a #8 cup so I'm running shorter beads but plan to pick up a larger cup tomorrow. Thanks guys!
-Markus-
Obviously I need more practice, then again I just started TIG 2 weeks ago. I have decent penetration but need it to be more consistent.
- Attachments
-
- IMG_4970.JPG (40.58 KiB) Viewed 4716 times
-
- IMG_4969.JPG (34.06 KiB) Viewed 4716 times
-Shannon
Ah..the all mighty tri clover fitting. I weld those daily 316L stainless for Food Grade apps. Typically with a food grade job you would do a autogenous weld (no filler), full penetration with an argon back purge. Using filler is not ideal as you'll have too much reinforcement in the I'd of the piping and that could hold microbes or bacteria.
On .065" wall I'm around 38-43amps (travel speed will alter that), #8 cup, gas lens 1/16" tungs, and no pulse. You should end up fairly smooth inside and out, silver in color on the ID and the outside can be pickled clean.
On .065" wall I'm around 38-43amps (travel speed will alter that), #8 cup, gas lens 1/16" tungs, and no pulse. You should end up fairly smooth inside and out, silver in color on the ID and the outside can be pickled clean.
- Attachments
-
- Here's a setup as I was welding....
- IMG_20141220_173941817.jpg (68.66 KiB) Viewed 4700 times
-
- Inside...
- IMG_20140813_195049169.jpg (37.7 KiB) Viewed 4700 times
-
- Here you can see where I welded on a 90° elbow
- IMG_20140417_221308.jpg (42.4 KiB) Viewed 4700 times
I weld stainless, stainless and more stainless...Food Industry, sanitary process piping, vessels, whatever is needed, I like to make stuff.
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
That looks great!
Okay, I originally wanted to not use filler rod and wondered if an autogenous weld (i'v heard it called fusion weld?) would be legitimate but was worried it would leave a weak area where the two came together. Using the filler metal adds another factor that could cause problems in the process (for an amateur like me). So if I'm getting a good flush weld inside with the autogenous weld method then it is the preferred way to do it with this material? Outstanding!
Okay, I originally wanted to not use filler rod and wondered if an autogenous weld (i'v heard it called fusion weld?) would be legitimate but was worried it would leave a weak area where the two came together. Using the filler metal adds another factor that could cause problems in the process (for an amateur like me). So if I'm getting a good flush weld inside with the autogenous weld method then it is the preferred way to do it with this material? Outstanding!
- Attachments
-
- Argon added at this end.
- IMG_4975.JPG (61.81 KiB) Viewed 4687 times
-
- Set up purge end
- IMG_4974.JPG (58.47 KiB) Viewed 4687 times
-Shannon
What pickling solution have you found works the best?Rick_H wrote:Ah..the all mighty tri clover fitting. I weld those daily 316L stainless for Food Grade apps. Typically with a food grade job you would do a autogenous weld (no filler), full penetration with an argon back purge. Using filler is not ideal as you'll have too much reinforcement in the I'd of the piping and that could hold microbes or bacteria.
On .065" wall I'm around 38-43amps (travel speed will alter that), #8 cup, gas lens 1/16" tungs, and no pulse. You should end up fairly smooth inside and out, silver in color on the ID and the outside can be pickled clean.
-Shannon
Good pics
Indeed mostly these welds are made without filler, but sometimes it's needed. Just make sure that your filler won't get oxidized during welding.
On your first picture you have a darker area on 6 o'clock. Is it from tacking without purge? Try to avoid blue color on HAZ. Very light yellow color is still acceptable in most cases and of course perfectly silver is the goal.
Little tip. Always purge as small area as possible and when purging with argon it's good to keep in mind that argon is heavier than air. So tilting pipe a little is very ideal.
Indeed mostly these welds are made without filler, but sometimes it's needed. Just make sure that your filler won't get oxidized during welding.
On your first picture you have a darker area on 6 o'clock. Is it from tacking without purge? Try to avoid blue color on HAZ. Very light yellow color is still acceptable in most cases and of course perfectly silver is the goal.
Little tip. Always purge as small area as possible and when purging with argon it's good to keep in mind that argon is heavier than air. So tilting pipe a little is very ideal.
-Markus-
That may have been the case, should have waited a couple more minutes before tacking. Thanks for the tip on argon. Blue color on HAZ? referring to the inside weld?Markus wrote:Good pics
Indeed mostly these welds are made without filler, but sometimes it's needed. Just make sure that your filler won't get oxidized during welding.
On your first picture you have a darker area on 6 o'clock. Is it from tacking without purge? Try to avoid blue color on HAZ. Very light yellow color is still acceptable in most cases and of course perfectly silver is the goal.
Little tip. Always purge as small area as possible and when purging with argon it's good to keep in mind that argon is heavier than air. So tilting pipe a little is very ideal.
I'm not using filler metal for the rest of this project, thanks for the insight guys. I've attached a picture of my first piece without it.
- Attachments
-
- inside w/o filler
- IMG_4976.JPG (37.27 KiB) Viewed 4672 times
-
- w/o filler
- IMG_4978.JPG (27.14 KiB) Viewed 4672 times
-Shannon
With a good purge an inside weld should be shiny silver, no color at all.
I made little purge dams to isolate my area at times, I can post pics tomorrow. The key is your cuts and edges have to be very square, near perfect. I also have a file and such that I only use for my 316l pipe and fittings.
Here's a link I saved from another forum, if you look down you'll see how to make your own purge plugs and damns. Its the 17th one down...
http://www.aws.org/cgi-bin/mwf/board_show.pl?bid=21
I made little purge dams to isolate my area at times, I can post pics tomorrow. The key is your cuts and edges have to be very square, near perfect. I also have a file and such that I only use for my 316l pipe and fittings.
Here's a link I saved from another forum, if you look down you'll see how to make your own purge plugs and damns. Its the 17th one down...
http://www.aws.org/cgi-bin/mwf/board_show.pl?bid=21
I weld stainless, stainless and more stainless...Food Industry, sanitary process piping, vessels, whatever is needed, I like to make stuff.
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
I guess for me the most challenging part is knowing if I'm getting good penetration while running the weld. I'm trying to keep my travel speed as fast as possible while watching the puddle to make sure I don't leave it behind and trying to keep a tight arc with little torch angle. I'm using a #8 cup with 3/16" tungsten at 38 amps, no pulse.
-Shannon
Are you making small circles or just a nice steady pull?
I weld stainless, stainless and more stainless...Food Industry, sanitary process piping, vessels, whatever is needed, I like to make stuff.
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
Not weaving but you can do small circles, steady pull or right now I've been playing with some pulse ,2.5pps, 55amps (my maxstar 15O doesn't all peak and background adjustment it is set at 50% each way) I normally weld around ,45amps on .065" wall 316l.Shannon wrote:Is there a benefit to weaving on this thin wall stainless?
If your not careful with small circles you can overheat but it usually helps beginners assure full pen. Its all is controlling your speed, torch angle and arc length.
I weld stainless, stainless and more stainless...Food Industry, sanitary process piping, vessels, whatever is needed, I like to make stuff.
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
ASME IX, AWS 17.1, D1.1
Instagram #RNHFAB
Thanks for the advice, I plan to play around with the settings and techniques.Rick_H wrote:Not weaving but you can do small circles, steady pull or right now I've been playing with some pulse ,2.5pps, 55amps (my maxstar 15O doesn't all peak and background adjustment it is set at 50% each way) I normally weld around ,45amps on .065" wall 316l.Shannon wrote:Is there a benefit to weaving on this thin wall stainless?
If your not careful with small circles you can overheat but it usually helps beginners assure full pen. Its all is controlling your speed, torch angle and arc length.
You guys have been great and very helpful.
-Shannon
Great to hear that you have improved your skills and interested to test new things
Personally I don't like doing little circles on thing walled pipe.
- It's slower
- It easily create too much heat and you end up with concavity
- It usually create rougher bead inside
Do you have TIG-finger? It's very useful on stainless pipes like these. With TIG-finger you can slide you hand more steady than normally and create constant penetration.
Personally I don't like doing little circles on thing walled pipe.
- It's slower
- It easily create too much heat and you end up with concavity
- It usually create rougher bead inside
Do you have TIG-finger? It's very useful on stainless pipes like these. With TIG-finger you can slide you hand more steady than normally and create constant penetration.
-Markus-
Return to “Tig Welding - Tig Welding Aluminum - Tig Welding Techniques - Aluminum Tig Welding”
Jump to
- Introductions & How to Use the Forum
- ↳ Welcome!
- ↳ Member Introductions
- ↳ How to Use the Forum
- ↳ Moderator Applications
- Welding Discussion
- ↳ Metal Cutting
- ↳ Tig Welding - Tig Welding Aluminum - Tig Welding Techniques - Aluminum Tig Welding
- ↳ Mig and Flux Core - gas metal arc welding & flux cored arc welding
- ↳ Stick Welding/Arc Welding - Shielded Metal Arc Welding
- ↳ Welding Forum General Shop Talk
- ↳ Welding Certification - Stick/Arc Welding, Tig Welding, Mig Welding Certification tests - Welding Tests of all kinds
- ↳ Welding Projects - Welding project Ideas - Welding project plans
- ↳ Product Reviews
- ↳ Fuel Gas Heating
- Welding Tips & Tricks
- ↳ Video Discussion
- ↳ Wish List
- Announcements & Feedback
- ↳ Forum News
- ↳ Suggestions, Feedback and Support
- Welding Marketplace
- ↳ Welding Jobs - Industrial Welding Jobs - Pipe Welding Jobs - Tig Welding Jobs
- ↳ Classifieds - Buy, Sell, Trade Used Welding Equipment
- Welding Resources
- ↳ Tradeshows, Seminars and Events
- ↳ The Welding Library
- ↳ Education Opportunities