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Up Topic Welding Industry / General Welding Discussion / GTAW sheilding gas
- - By rebel74 (*) Date 03-20-2007 18:50
What are the benifits from using 75% helium 25% argon than using 100% argon?
Parent - - By Kix (****) Date 03-20-2007 19:09
75/25 ARG/HEL mix thats a bit drastic, but what your doing is making the puddle hotter with fewer amps.  Like if your machine maxes out at 200amps and you're pushin it to the max just to barely get the part to melt at 200amps you can add some helium to the argon to get a bit more out of your machine.  Makes your aluminum ripple with GTAW using 4043 filler come out shiny and sweet also because of that hotter puddle.  People use helium mixes for better pennetration characteristics, but the most i've ever had to use was a 50/50 argon helium mix.
Parent - - By js55 (*****) Date 03-20-2007 19:41
Kix is right. 75% He is extreme. Even for Aluminum. There are no advantages for most other alloys. He requires greater flow rates due to the same reason that it makes your voice funny. Its more expensive and destabilizes the arc, but it does accomodate aluminums' high thermal conductivity, the predominant reason it is added in the first place.
Parent - - By rebel74 (*) Date 03-21-2007 15:26
We weld tubing for the oilfield industry, mostly different grades of carbon steel. I keep telling my metelurgist that we are wasting money on it. Everything we weld with that mixture gives the welders problems, but on the proceedures that require 100% argon they do fine. Any suggestions?
Parent - By js55 (*****) Date 03-21-2007 15:42
rebel74,
I know of no advantages whatsoever for using He on carbon steel. The heat characterisitcs will of course still be valid, but whatever gains there are will be lost in added expense and difficulty for your welders, as you have experienced.
Carbon steel flows so readily that you can actualy turn up the amps until the arc force starts pushing the puddle awy from you, and still achieve fusion.
Parent - - By aevald (*****) Date 03-20-2007 19:40
Hello rebel74, as Kix somewhat touched on and as was pointed out to me from another post by js55, the helium percentage in the mix can have a considerable effect on the penetration/fusion characteristics of the weld bead. In some instances this will be a favorable characteristic and that is the main reason for selecting such a mix. Also, as Kix pointed out, the addition of helium in varying percentages will allow for the "hotter" feel to the weld pool. Would be curious to know the application that you are using this for? Regards, aevald
Parent - - By devo (***) Date 03-20-2007 20:35
According to my notes from a Tig class at Lincoln Electric, the advantages of He vs. Ar are a smaller HAZ, and higher arc voltage (23-24V) with He.  The arc is around 1.7x hotter.  It is also 10x as expensive as Ar and even more sensitive to contamination.   On a side note, most shielding gases( O2, Ar, Co2, N) are obtained through air liquefaction(i.e cool air until it becomes liquid, then evaporate the separate gases).  Helium, while present in our atmosphere, is more readily obtained from underground wells.  This is a big part of the cost.  But like any natural resource, it is running out.  So who knows, maybe our great grandchildren will be running pure argon no matter what.
Parent - - By DaveBoyer (*****) Date 03-21-2007 03:21
I am not sure about right now, but a few months ago Airgas sent out a notice that helium was in short supply, and they were unsure if they would be able to meet everyone's needs. Or maybee they were just priming us for a price increase.
Parent - - By aevald (*****) Date 03-21-2007 04:00
Hello DaveBoyer, as a bit of a sidelight on this helium thing, I recall once hearing that the federal government has quite a stockpile of helium. I recall hearing that this was a result of it's use during World War I. Don't know how accurate that statement truly is or if these supplies still do or ever did exist. Just something I heard. Regards, aevald
Parent - By 803056 (*****) Date 03-21-2007 04:29
Ronald Regan decided the government shouldn't be in the business of writing military specifications and shouldn't be competing with business. He sold all the helium reserves. Prior to that, Uncle Sam owned all the helium reserves as strategic materials and doled it out sparingly and pretty much controlled the prices.

One article I read said it has been estimated that the US has reserves available that should last for the next 100 years. At one time, all the helium was obtained from wells in West Texas. However, it seems that helium is generally present in natural gas as well.

Now, this is what I've read and we all know that the "rags" have been known to "tell it like it is with a twist." So, check the facts before you accept this as gospel.

Best regards - Al
Parent - - By billvanderhoof (****) Date 03-21-2007 05:17
Between the world wars the US experimented with rigid dirigibles and then blimps.  The blimps stayed in service through WWII and until the late 1950s in antisubmarine service.  Goodyear built about 250 blimps for the Navy and Army each contained about 125000 cu ft of helium.  Sometime in the late 60's I happened by one of the Goodyear blimps teathered in a field and stopped to talk with the attendents.  If I remember correctly they said there was something like $40000 of high purity helium in the gasbag.  I suspect that the end of lighter than air aviation in the military substantially reduced the need for a large strategic reserve of helium.
Bill
Parent - - By aevald (*****) Date 03-21-2007 06:16
Thanks for the replies gentlemen, I do believe that the stories that I had heard closely matched much of what you have relayed. Definitely many interesting things in the history behind and the origins of something like helium. Rather ironic that something that was originally used for aeronautics would end up being a major player in the welding industry and so much more. Regards, aevald
Parent - By MDG Custom Weld (***) Date 03-21-2007 13:56
This is the latest in the "Cartel" type of natural resource companies.  As with oil, chrome, copper, and nickel, the companies that have control of the largest stake inflate the market by controlling the production limits.  You are right that the He reserves are limited, some sources say <100 yrs while others say 100's of yrs.  All in all, they have been successful in inflating the prices to line the pockets of the share holders, while manufacturing and end users pick up the tab.
Parent - - By rebel74 (*) Date 03-21-2007 15:22 Edited 03-21-2007 15:48
We are welding tubing for the oilfield industry, size varies from 3/4" to 2 7/8" with a wall thickness of .095 to 0.175. It is different grades of carbon steel. We are not pushing our machines, in fact we have to use chill blocks to draw the heat out of the tubing. Me and my metalurgist has been going around and around over the issue.
Parent - - By DaveBoyer (*****) Date 03-22-2007 03:32
I think helium/argon mixes are common for thick aluminum and for copper due to thermal conductivity, I don't recall any recomendations for their use on carbon steel. As for helium use at My buddy/boss's operation, he has a garden center as part of  His buisiness and is the FTD florist for the area, as part of the deal They fill party baloons. Talk about a waste of a limited resourse, but the baloons just aren't the same hanging down from a string...
Parent - By Kix (****) Date 03-22-2007 11:59
Yeah shouldn't need helium for carbon steel tig roots.  Use preheat if you have too, but that root goes in there a lot easier if it's cool. 
Parent - - By js55 (*****) Date 03-22-2007 13:32
Your metallurgist is recommending the higher energy He as a gas mix while at the same time you are using chill blocks? I'd sure be interested to hear his metallurgical justification. Perhaps there is some metallurgical phenomena involving defeating purposes we need to be made aware of.
Sorry for the sarcasm. I couldn't resist.
Parent - - By rebel74 (*) Date 03-22-2007 13:41
The sarcasum is ok, but now you know what I am up against, I have told him that same thing
Parent - - By js55 (*****) Date 03-22-2007 14:24
Perhaps a cost/benefit study. There will be no benefit (or at least he will have to justify his argument in a written form), but there will be extensive costs. Maybe get the bean counters on your side.
Parent - - By rebel74 (*) Date 03-22-2007 15:50
I talked to him and  his explanation was helium made the puddle flow better and is a better shielding gas. He is book smart but never burned a rod in his life.
Parent - By Kix (****) Date 03-22-2007 16:09 Edited 03-22-2007 16:12
Welp, that said it right there...  So then i would have to go and say it's there money and as long as you get a pay check each week or every 2 weeks your good to go.   I don't know where some of these guys come up with this stuff??  Is it true you have to have at least 5 years of welding background to get your CWI now?
Parent - - By js55 (*****) Date 03-22-2007 16:11
Rebel74,
I can certainly be symapthetic to your problem. I 'm not sure where he would have read that He is 'better'. Based upon what criteria? Makes the puddle flow better? For carbon steel? I don't really know what that would mean. Helium certainly has characteristics that can be utilized to advantage in specific applications. But not carbon steel.
Flow better for what purpose? Wetting? There is no wetting advantage to He. Appearance? No. Fusion? Is there a problem with Ar fusion? Mechanical properties? if anything less energy is better. And I wasn't aware there was a carbon steel 'flow' problem in the first place.
It would be my opinon that reinventing the wheel in this application is a waste of time and money.
Parent - - By ssbn727 (*****) Date 03-22-2007 17:45
Ditto on that Js55!

Who is this person that's a metallurgist? Could you please invite him on to the forum so he could explain, no wait - justify his decisions in welding with Ar/He mix on carbon steel piping with those diameters & wall thicknesses?

It would be very interesting Rebel 74, Js55 to read what this individual has to say in his justification for using an Ar/He mix as a shielding gas for carbon steel... I've used it on thick aluminum, and some thick 316L stainless pipe fittings but come on!!! Carbon Steel???

For what it's worth Rebel74, I think this person needs to go back to his reference books that cover "Welding Metallurgy" as opposed to what he's referring to as process metallurgy? or basically steelmaking if that's what this person is thinking??? After all, a Metallurgist does'nt always have the same background that a welding engineer would have and sadly to say, most Material Scientist types these days only get rudimentary training in "Welding Metallurgy" if any! They only go over the basics when it comes to joining metals.

I would suggest to get the welding engineer involved or someone else that has more expertise in welding than that metallurgist because, this person really sounds confused and I'm not a metallurgist!!!
Good luck in your struggle Rebel74, and see if you can "cajole" this person into explaining their decision for using the Ar/He mix for carbon steel GTAW here in the forum.

Respectfully,
Henry
Parent - - By rebel74 (*) Date 03-23-2007 15:15
I will see what I can do about getting him on here. He is old and stuck in the past, he said that originaly the only gas they used as a sheilding gas we HE, I said yeah in 1937, but now tech. has changed so much that he neeeds to get up to speed.

Woody
Parent - By rebel74 (*) Date 03-27-2007 18:30
I would like thank everybody for there input, it was very helpful.

Woody
Up Topic Welding Industry / General Welding Discussion / GTAW sheilding gas

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