GTAW- Manual, Semiauto or Machine????

Date 07-11-2008 12:51

Have a question that hopefully some of you can give me some insight. We work under ASME guidelines using mostly GTAW. QW-356 covers Manual and semiautomatic Essential variables for GTAW. Where I work we use the manual GTAW process and a GTAW with a wire feeder. The welders all refer to the wire feeder method as "the automatic". Now I know it is not truely automatic welding in the sense that ASME and AWS define automatic welding, but I am not sure what it really is. We do all of our welding on rotary positioners and the "automatic" as they call it, utilizes a Jetline system where once started they just sit there and watch the puddle to make sure that it does stay in the center of the joint. Travel speed is set by the positioner. It does have an oscillator that can be preset for larger welds, and there is also an arc votage control. What I am trying to figure out is, for certification sake, what kind of welding is this considered? I think it would be either semiautomatic or machine, but I am not sure. Our guys are already certified in all positions with manual GTAW. so I would think that if it were to be considered semiautomatic that they would be qualified already. Thanks in advance for any help

By swsweld (****)

Date 07-11-2008 13:48 Edited 07-11-2008 17:05

Machine or mechanized welding.

QW-361.2 gives the essential variables for machine welding

361.1 gives it for automatic. definitely is not automatic

By js55

Date 07-11-2008 14:01 Edited 07-11-2008 14:08

You're desciption sounds like 'machine'. The wire is not manual, the head adjustment is not manual, and you say Jetline, do you have Automatic voltage Control?
If you place the part in the positioner yourself, and do some adjustment to the head to get it in position and make adjustments on parameters to a certain extent (even with AVC) it is machine not automatic.
"they just sit there and watch the puddle to make sure that it does stay in the center of the joint." This is a machine application.
AWS A3.0 is of little help. The definitions here (automatic, machine, semi-automatic, manual) in my opinion are grossly inadequate. Realizing we're talking ASME anyhow.

By js55

Date 07-11-2008 14:12

I know ASME has their own definition of these process types which if memory serves is far preferrable to the AWS version. Though my memory fails as to where they are.

By jsdwelder (***)

Date 07-11-2008 15:00

Thanks for the reply. If in fact this is machine welding, then what would be considered semiautomatic GTAW? BTW, yes, it does have an automatic voltage control. I've never had the chance to work with a set up like this before coming here, but it is a pretty slick operation. The way it sounds I will fact have to now qualify our welders as machine operators.

By jon20013 (*****)

Date 07-11-2008 15:22

Gents, you are likely talking about an orbital type GTAW and from past recollection it is considered an automatic process even though controlled via pendant. Your variables for operator will be in the end sections of QW-300.

Again, speaking just from memory, Machine welding is more akin to a truly automated process (hope I've got that right!).

By js55

Date 07-11-2008 15:38 Edited 07-11-2008 15:41

jon,
If the part is rotated in a positioner it wouldn't be Orbital. Also, I've used the Jetline (and similar) stuff before. Cold wire/hot wire feeds, AVC, etc. even maganetic arc oscillation, in what sounds like its very similar to this application. You can tie this stuff into a fixturing type apparatus and make it automatic, I believe the Jetline stuff lends itself very well to periferal automation, but its generally operated as a machine process. Its just like SAW only its GTAW with AVC.
But I would agree that orbital is closer to an automatic application and I would generally classify it as such. Though I have seen orbitals where adjustments were made on the fly. This makes it sorta gray.
FCAW orbitals have a tendency to slip more into machine/auto hybrid than the GTAW orbitals do.

By js55

Date 07-11-2008 15:48

I suppose it can be argued there really isn't a semi-auto GTAW. But, if you have a 'machine' or 'auto' feed of the wire (we used these occaisonlly for fill and caps on pipe-though they never really caught on) yet still manipulating the torch manually, it can be argued as semi auto cold wire feed GTAW. And I believe I would argue it as semi auto.
Semi auto implies some kind of manual manipulation of the the head (or torch) to put it crudely in my opinion. And the standard semi auto for FCAW and GMAW is exactly that. Manual manipulation of the head while the wire is fed in an automatic manner.

By swsweld (****)

Date 07-11-2008 16:47 Edited 07-11-2008 17:04

Could a cold wire feeder set up be considered a semi automatic GTAW process?

I think the automatic process is a process that after the arc is initiated you have no control of or manipulation of the arc except to terminate it. i.e. The BRB.

Even the positioner roller can be adjusted for travel speed.

jsdwelder, if you qualify your welders will you be doing this in the 1G only? Do you use this for field work or welds in the shop that cannot be rotated?

By jsdwelder (***)

Date 07-11-2008 18:33

All of our welds done with this process are done in the shop in either 1G or 1F position.

By pipewelder_1999 (****)

Date 07-13-2008 11:39

Its my opinion that a GTAW setup with HW/CW is Semi Automatic as long as it is controlled by a welders hand. Put the same torch in a stand and move the part by machine, its machine welding.