Gas lens

By Lawrence (*****)

Date 11-22-2010 14:25

Um.. interesting way you put the question.

Don't know why a gas lens would be useful in cup walking applications. The whole purpose of a gas lens is to produce a larger gas covered circle around the weld to help keep shield gas on the trailing edge of the puddle and to accomodate a slightly longer stickout for the tungsten electrode in some cases.

Neither of those issues are likely to come up in a cup walking pipe joint.

For freehand work on stainless and super alloys they can be a big help.. Especially when the color of the oxide on the crown of the weld is an issue.

Since the gas lens must have a different shape than the cups you have been using up until now.. Of course they are going to walk differently, maybe not too good, depending on the shape of the gas lens cup.

Since your beginning.. You may not want to try a whole lot of different things until you have the first things mastered.. Unless your instructors are asking you to use gas lenses I would stick to regular cups and collets. If they are the ones pushing for gas lenses.. They must have explained why they wanted them right?

By sjsevier (*)

Date 11-24-2010 03:35

Hey Lawrence I bought a flex head torch from one of my instructors and he threw in a few gas lens and he was a pipe welder before an instructor, and he said that in windy conditions the gas lens would keep my weld covered and not blow out my argon.

By Lawrence (*****)

Date 11-24-2010 05:11

Walking the cup with a flex torch would be pretty tricky too. :)

Gas lenses do provide better coverage so they can help when the air is moving.

By welderbrent (*****)

Date 11-22-2010 15:11 Edited 11-22-2010 21:45

Lawrence gave a very good response, I'm just going to second that from my own perspective. I am no GTAW master though I am certified with it. I find it (edit:the gas lens) very useful for SS & Alum as well as a few othe projects but usually not for pipe applications. Not that it can't be done.

Have a Great Day, Brent

By Tommyjoking (****)

Date 11-22-2010 20:50

As usual Law gave a to the point all bases covered answer. I see little point to using a gas lens on pipe unless it is exotics ("maybe" some SS). I have never tried to walk a gas lens and I could see it being cumbersome if not just plain goofy. As already stated a lens is really for better gas coverage on the trailing edge, typically in crucial applications.

By sjsevier (*)

Date 11-24-2010 03:30

Hey Brent I was told that when pipe welding in stronger wind conditions the gas lens would give me better coverage.

By mightymoe (**)

Date 11-22-2010 21:48

I'd recommend that you stick with what ever you are most comfortable with.
I've used both and in the end they are both round. They walk the same to me.

By Blaster (***)

Date 11-22-2010 22:14

I like gas lenses. I prefer them for almost all TIG welding unless there is some reason not to use them. The main exception is walking the cup. I am not too fond of them for beginners as if one is prone to dipping the electrode, the screen in the lens gets fouled up pretty quick.

As far as walking the cup, the best cup every invented IMO is the Lava cup from Weld Craft. They are dirty white in appearance. Their big advantage is their edge doesn't readily glass up like pink cups typically do. The material is slightly crumbly so any glassing can be removed and/or wears off during cup walking. A contaminated or glassed area can be reconditioned on a belt sander to some extend if need be... whereas a pink cup just pretty much wears a hole in the belt.

The material seems to give much better traction than the pink cups... particularly better than a glassed up pink cup.

The down side is I just talked to Weld Craft today and the rats just moved Lava cup production to communist China. The pink ones went some time ago. I don't believe there is a single manufacturer of TIG cups in the USA any more.

By js55

Date 11-23-2010 13:54

Well, let me just throw this contrarian point out there. We ran oodles of carbon steel with gas lenses for a couple of different reasons.
We were running the roll out pipe welds essentially downhill (10:00), hot and fast (a 12" root pass in ~ 60 seconds).
To run that fast you needed plenty of preheat so we laid the torch back at an extreme angle (so far in fact that we would heat the torches and bend the body back until the stem would contact your hand), extended the stickout, and cranked up the gas, in which case we needed the gas lens to tumble the gas to prevent aspiration and turbulance.
Add to this that because the welder had to position himself over the pipe in sometimes uncomfortable body angles (especially with preheated joints) we lightened up the torches by using smaller ones, in which case we needed the additional gas for cooling purposes.
The 3 biggest problems were the torches would get really hot, the puddle would create a wave in front if you pushed the envelope too much, and more importantly, the shoulder of the gas lens would sometimes ride the bevel on larger pipe and slip if the welder wasn't careful.
Unconventional to be sure, but advantageous nonetheless. And VERY productive.

By Lawrence (*****)

Date 11-23-2010 15:07

Not contrarian at all. Just a special application, and we don't argue with succsess eh?

I would like to see what your talking about too.

By js55

Date 11-23-2010 15:33

Argue with success. Nope. The technique was introduced to me by some very accomplished welders from a fabrication shop in Utah when I was still in California. These guys were kickin my azz in production. So no, I didn't argue. I learned. And then we developed it to its ultimate envelope.
Another advantage is that if you GTAW tack you do NOT need to stop and grind. You consume(unlike GMAW). You can do it with GMAW tacks as well but its much more difficult. If there is issue with the tacks like porosity (not IP, that is irrelevent-You can achieve pen from the melt of the tack) it will let you know. You light up and don't stop til the root is done.
A standard wall weld would consist of a GTAW root, a very fast FCAW hot pass (basically just skipping over the root to provide material support (you can actually run so fast you are sittin at almost 9:00) And then a Fill and Cap simultaneously with the wire speed cranked. The idea is to minimize the amount of material laid down by slow wire speed and maximize the amount of material laid down with fast wire speed.
The GTAW techniques actually blows GMAW out of the water, but I have a hard time convincing people.

By Jim Hughes (***)

Date 11-23-2010 16:43

When I was welding for a living, convenience was huge to me. ( you know the old saying, "want a job done fast give it to a lazy man, and he will find an easy way to do it") :) I spent the last years of my welding carrier in a fab shop where we welded mostly Sch 10 S.S. Mostly ASME B31.3 S.C (very gravy work if you can get it) so I and all the other welders in this shop used a large Gas Lens and a # 12 cup for everything. We free handed (fingered)socket welds, even the C.S which was about 20% of our work. What ever was thrown at us, it was a Large Gas Lens and a #12 cup. Never changed it. To be honest a lot of the guys freehanded (fingered) everything. Due to my nuke experiance I was a cup walker, which was a neg. in this fab shop in South Texas. Shop had a less than 1% reject rate.

Thanks
Jim